Painting

Painting is the practice of applying paint, pigment, color or other medium[1] to a surface (support base). The application of the medium is commonly applied to the base with a brush but other objects can be used(Sony Vaio VGN-FZ battery). In art, the term painting describes both the act and the result of the action. Paintings may have for their support such surfaces as walls, paper, canvas, wood, glass, lacquer, clay, copper or concrete, and may incorporate multiple other materials including sand, clay, paper, gold leaf as well as objects(Sony VGP-BPS8 battery).

Painting is a mode of expression and the forms are numerous. Drawing, composition or abstraction and other aesthetics may serve to manifest the expressive and conceptual intention of the practitioner(Sony VGP-BPL9 battery). Paintings can be naturalistic and representational (as in a still life or landscape painting), photographic, abstract, be loaded with narrative content, symbolism, emotion or be political in nature.

A portion of the history of painting in both Eastern and Western art is dominated by spiritual motifs and ideas(Sony VGP-BPS9 battery); examples of this kind of painting range from artwork depicting mythological figures on pottery to Biblical scenes rendered on the interior walls and ceiling of The Sistine Chapel, to scenes from the life of Buddha or other scenes of eastern religious origin(Sony VGP-BPL11 battery).

Elements

Intensity

What enables painting is the perception and representation of intensity. Every point in space has different intensity, which can be represented in painting by black and white and all the gray shades between. In practice, painters can articulate shapes by juxtaposing surfaces of different intensity(Sony VGP-BPL15 battery); by using just color (of the same intensity) one can only represent symbolic shapes. Thus, the basic means of painting are distinct from ideological means, such as geometrical figures, various points of view and organization (perspective), and symbols(Sony VGN-FZ460E battery). For example, a painter perceives that a particular white wall has different intensity at each point, due to shades and reflections from nearby objects, but ideally, a white wall is still a white wall in pitch darkness. In technical drawing, thickness of line is also ideal, demarcating ideal outlines of an object within a perceptual frame different from the one used by painters(Sony VGP-BPS11 battery).

Color and tone

Color and tone are the essence of painting as pitch and rhythm are of music. Color is highly subjective, but has observable psychological effects, although these can differ from one culture to the next. Black is associated with mourning in the West, but in the East, white is. Some painters, theoreticians, writers and scientists(SONY VAIO VGN-FZ4000 Battery), including Goethe,Kandinsky, and Newton, have written their own color theory. Moreover the use of language is only a generalization for a color equivalent. The word "red", for example, can cover a wide range of variations on the pure red of the visible spectrum of light. There is not a formalized register of different colors in the way that there is agreement on different notes in music(Sony VGP-BPS10 battery), such as C or C♯ in music. For a painter, color is not simply divided into basic and derived (complementary or mixed) colors (like red, blue, green, brown, etc.).

Painters deal practically with pigments, so "blue" for a painter can be any of the blues: phtalocyan, Paris blue, indigo, cobalt, ultramarine, and so on(Sony VGP-BPS13 battery). Psychological, symbolical meanings of color are not strictly speaking means of painting. Colors only add to the potential, derived context of meanings, and because of this the perception of a painting is highly subjective. The analogy with music is quite clear—sound in music (like "C") is analogous to light in painting( Sony VGP-BPS3 battery), "shades" to dynamics, and coloration is to painting as specific timbre of musical instruments to music—though these do not necessarily form a melody, but can add different contexts to it(Sony VGP-BPS2 battery).

Rhythm

Rhythm is important in painting as well as in music. If one defines rhythm as "a pause incorporated into a sequence", then there can be rhythm in paintings. These pauses allow creative force to intervene and add new creations—form(Sony Vaio VGN-FZ21M battery ), melody, coloration. The distribution of form, or any kind of information is of crucial importance in the given work of art and it directly affects the esthetical value of that work. This is because the esthetical value is functionality dependent, i.e. the freedom (of movement) of perception is perceived as beauty(Sony VGN-FZ150E battery). Free flow of energy, in art as well as in other forms of "techne", directly contributes to the esthetical value.

Non-traditional elements

Modern artists have extended the practice of painting considerably to include, for example, collage, which began with Cubism and is not painting in the strict sense. Some modern painters incorporate different materials such as sand(Sony VGN-FZ15 battery), cement, straw or wood for their texture. Examples of this are the works of Jean Dubuffet and Anselm Kiefer. There is a growing community of artists who use computers to paint color onto a digital canvas using programs such as Adobe Photoshop, Corel Painter, and many others. These images can be printed onto traditional canvas if required(Sony VGN-FZ15L battery).

History

The oldest known paintings are at the Grotte Chauvet in France, claimed by some historians to be about 32,000 years old. They are engraved and painted using red ochreand black pigment and show horses, rhinoceros, lions, buffalo, mammoth or humans often hunting(Sony Vaio VGN-FZ18M battery). However the earliest evidence of painting has been discovered in two rock-shelters in Arnhem Land, in northern Australia. In the lowest layer of material at these sites there are used pieces of ochre estimated to be 60,000 years old. Archaeologists have also found a fragment of rock painting preserved in a limestone rock-shelter in the Kimberley region of North-Western Australia(Sony VGN-FZ15T battery), that is dated 40 000 years old. There are examples of cave paintings all over the world—in India, France, Spain, Portugal, China, Australia, etc.

In Western cultures oil painting and watercolor painting have rich and complex traditions in style and subject matter. In the East, ink and color ink historically predominated the choice of media with equally rich and complex traditions(Sony VGN-FZ480E battery).

The invention of photography had a major impact on painting. In 1829, the first photograph was produced. From the mid to late 19th century, photographic processes improved and, as it became more widespread, painting lost much of its historic purpose to provide an accurate record of the observable world(Sony VGN-FZ61B battery). There began a series of art movements into the 20th century where the Renaissance view of the world was steadily eroded, through Impressionism, Post-Impressionism, Fauvism, Expressionism,Cubism and Dadaism. Eastern and African painting(Sony VGN-FZ31E battery), however, continued a long history of stylization and did not undergo an equivalent transformation at the same time.

Modern and Contemporary Art has moved away from the historic value of craft and documentation in favour of concept; this led some to say in the 1960s that painting, as a serious art form, is dead(Sony VGN-FZ340E battery). This has not deterred the majority of living painters from continuing to practice painting either as whole or part of their work. The vitality and versatility of painting in the 21st century belies the premature declarations of its demise. In an epoch characterized by the idea of pluralism, there is no consensus as to a representative style of the age(Sony VGN-FZ180E battery). Important works of art continue to be made in a wide variety of styles and aesthetic temperaments, the marketplace being left to judge merit.

Among the continuing and current directions in painting at the beginning of the 21st century are Monochrome painting, Hard-edge painting, Geometric abstraction, Appropriation, Hyperrealism, Photorealism(Sony VGN-FZ18E battery),Expressionism, Minimalism, Lyrical Abstraction, Pop Art, Op Art, Abstract Expressionism, Color Field painting, Neo-expressionism, Collage, Intermedia painting, Assemblage painting, Computer artpainting,Postmodern painting, Neo-Dada painting, Shaped canvas painting, environmental mural painting, traditional figure painting, Landscape painting, Portrait painting, and paint-on-glass animation(Sony VGP-BPL4 battery).

Aesthetics and theory

Aesthetics is the study of art and beauty; it was an important issue for such 18th and 19th century philosophers as Kant or Hegel. Classical philosophers like Plato and Aristotle also theorized about art and painting in particular; Plato disregarded painters (as well as sculptors) in his philosophical system(Sony VGN-FZ160E battery); he maintained that painting cannot depict the truth—it is a copy of reality (a shadow of the world of ideas) and is nothing but a craft, similar to shoemaking or iron casting. By the time of Leonardo painting had become a closer representation of the truth than painting was in Ancient Greece. Leonardo da Vinci(Sony VGN-FZ15M battery), on the contrary, said that "Pittura est cousa mentale" (painting is a thing of the mind). Kant distinguished betweenBeauty and the Sublime, in terms that clearly gave priority to the former. Although he did not refer particularly to painting, this concept was taken up by painters such as Turner andCaspar David Friedrich(Sony Vaio VGN-FZ18G battery).

Hegel recognized the failure of attaining a universal concept of beauty and in his aesthetic essay wrote that Painting is one of the three "romantic" arts, along with Poetry and Musicfor its symbolic, highly intellectual purpose. Painters who have written theoretical works on painting include Kandinsky and Paul Klee(Sony VGN-FZ345E battery). Kandinsky in his essay maintains that painting has a spiritual value, and he attaches primary colors to essential feelings or concepts, something that Goethe and other writers had already tried to do(Sony VGP-BPS14 battery).

Iconography is the study of the content of paintings, rather than their style. Erwin Panofsky and other art historians first seek to understand the things depicted, then their meaning for the viewer at the time, and then analyze their wider cultural, religious, and social meaning(Sony PCGA-BP1N battery).

In 1890, the Parisian painter Maurice Denis famously asserted: "Remember that a painting—before being a warhorse, a naked woman or some story or other—is essentially a flat surface covered with colors assembled in a certain order." Thus, many 20th-century developments in painting(Sony PCGA-BP2E battery), such as Cubism, were reflections on the means of painting rather than on the external world, nature, which had previously been its core subject. Recent contributions to thinking about painting has been offered by the painter and writer Julian Bell. In his book What is Painting? (Sony VGN-FZ11S battery), Bell discusses the development, through history, of the notion that paintings can express feelings and ideas. In Mirror of The World Bell writes:

‘A work of art seeks to hold your attention and keep it fixed: a history of art urges it onwards, bulldozing a highway through the homes of the imagination(Sony VGN-FZ17L battery).

Painting media

Different types of paint are usually identified by the medium that the pigment is suspended or embedded in, which determines the general working characteristics of the paint, such as viscosity, miscibility, solubility, drying time, etc(Sony VGN-FZ17G battery).

Oil

Oil painting is the process of painting with pigments that are bound with a medium of drying oil—especially in early modern Europe, linseed oil. Often an oil such as linseed was boiled with a resin such as pine resin or even frankincense; these were called 'varnishes' and were prized for their body and gloss(Sony VGN-FZ17 battery). Oil paint eventually became the principal medium used for creating artworks as its advantages became widely known. The transition began with Early Netherlandish painting in northern Europe, and by the height of the Renaissance oil painting techniques had almost completely replaced tempera paints in the majority of Europe(Sony VGP-BPS18 battery).

Pastel

Pastel is a painting medium in the form of a stick, consisting of pure powdered pigment and a binder. The pigments used in pastels are the same as those used to produce all colored art media, including oil paints; the binder is of a neutral hue and low saturation. The color effect of pastels is closer to the natural dry pigments than that of any other process(Sony VGP-BPS15 battery). Because the surface of a pastel painting is fragile and easily smudged, its preservation requires protective measures such as framing under glass; it may also be sprayed with a fixative. Nonetheless, when made with permanent pigments and properly cared for, a pastel painting may endure unchanged for centuries. Pastels are not susceptible(Sony VGP-BPS12 battery), as are paintings made with a fluid medium, to the cracking and discoloration that result from changes in the color, opacity, or dimensions of the medium as it dries.

Acrylic

Acrylic paint is fast drying paint containing pigment suspension in acrylic polymer emulsion. Acrylic paints can be diluted with water, but become water-resistant when dry(Sony VGP-BPL12 battery). Depending on how much the paint is diluted (with water) or modified with acrylic gels, media, or pastes, the finished acrylic painting can resemble a watercolor or an oil painting, or have its own unique characteristics not attainable with other media. The main practical difference between most acrylics and oil paints is the inherent drying time(Sony VGP-BPL7 battery). Oils allow for more time to blend colors and apply even glazes over underpaintings. This slow drying aspect of oil can be seen as an advantage for certain techniques, but in other regards it impedes the artist trying to work quickly(Sony VGN-FZ290 battery).

Watercolor

Watercolor is a painting method in which the paints are made of pigments suspended in a water soluble vehicle. The traditional and most common support for watercolor paintings is paper; other supports includepapyrus, bark papers, plastics, vellum or leather, fabric, wood, and canvas(Sony VGN-FZ29VN battery). In East Asia, watercolor painting with inks is referred to as brush painting or scroll painting. In Chinese, Korean, and Japanese painting it has been the dominant medium, often in monochrome black or browns. India, Ethiopia and other countries also have long traditions. Fingerpainting with watercolor paints originated in China(Sony VGN-SZ56 battery).

Ink

Ink paintings are done with a liquid that contains pigments and/or dyes and is used to color a surface to produce an image, text, or design. Ink is used for drawing with a pen, brush, or quill. Ink can be a complex medium, composed of solvents, pigments, dyes, resins, lubricants(Sony VGN-SZ55 battery), solubilizers, surfactants, particulate matter, fluorescers, and other materials. The components of inks serve many purposes; the ink’s carrier, colorants, and other additives control flow and thickness of the ink and its appearance when dry.

Hot wax

Encaustic painting, also known as hot wax painting, involves using heated beeswax to which colored pigments are added(Sony VGN-FZ220E battery). The liquid/paste is then applied to a surface—usually prepared wood, though canvas and other materials are often used. The simplest encaustic mixture can be made from adding pigments to beeswax, but there are several other recipes that can be used—some containing other types of waxes, damar resin, linseed oil, or other ingredients(Sony VGN-FZ11Z battery). Pure, powdered pigments can be purchased and used, though some mixtures use oil paints or other forms of pigment. Metal tools and special brushes can be used to shape the paint before it cools, or heated metal tools can be used to manipulate the wax once it has cooled onto the surface(Sony VGN-FZ11M battery). Other materials can be encased or collaged into the surface, or layered, using the encaustic medium to adhere it to the surface.

Fresco

Fresco is any of several related mural painting types, done on plaster on walls or ceilings. The word fresco comes from the Italian word affresco which derives from the Latin word for "fresh". Frescoes were often made during the Renaissance and other early time periods. Buon fresco technique consists of painting in pigment mixed with water on a thin layer of wet(Sony Vaio VGN-FZ31M battery), fresh, lime mortar or plaster, for which the Italian word for plaster, intonaco, is used. A secco painting, in contrast, is done on dry plaster (secco is "dry" in Italian). The pigments require a binding medium, such as egg (tempera), glue or oil to attach the pigment to the wall(Sony Vaio VGN-FZ31Z battery).

Gouache

Gouache is a type of paint consisting of pigment suspended in water. Gouache differs from watercolor in that the particles are larger, the ratio of pigment to water is much higher, and an additional, inert, white pigment such as chalk is also present. Like all watermedia, it is diluted with water. This makes gouache heavier and more opaque, with greater reflective qualities(Sony VGN-FZ19VN battery).

Enamel

Enamels are made by painting a substate, typically metal, with frit, a type of powdered glass. Minerals called color oxides provide coloration. After firing at a temperature of 750–850 degrees Celsius (1380–1560 degrees Fahrenheit), the result is a fused lamination of glass and metal(Sony Vaio VGN-FZ38M battery). Enamels have traditionally been used for decoration of precious objects, but have also been used for other purposes. In the 18th century, enamel painting enjoyed a vogue in Europe, especially as a medium for portrait miniatures. In the late 20th century, the technique of porcelain enamel on metal has been used as a durable medium for outdoor murals(Sony Vaio VGN-FZ31S battery).

Spray paint

Aerosol paint (also called spray paint) is a type of paint that comes in a sealed pressurized container and is released in a fine spray mist when depressing a valve button. A form of spray painting, aerosol paint leaves a smooth, evenly coated surface. Standard sized cans are portable, inexpensive and easy to store. Aerosol primer can be applied directly to bare metal and many plastics(Sony VGN-FZ11L battery).

Speed, portability and permanence also make aerosol paint a common graffiti medium. In the late 1970s, street graffiti writers' signatures and murals became more elaborate and a unique style developed as a factor of the aerosol medium and the speed required for illicit work(Sony VGN-FZ15G battery). Many now recognize graffiti and street art as a unique art form and specifically manufactured aerosol paints are made for the graffiti artist. A stencil can be used to protect a surface except the specific shape that is to be painted. Stencils can be purchased as movable letters, ordered as professionally cut logos, or hand-cut by artists(Sony VGP-BPS9/B battery).

Tempera

Tempera, also known as egg tempera, is a permanent, fast-drying painting medium consisting of colored pigment mixed with a water-soluble binder medium (usually a glutinous material such as egg yolk or some other size). Tempera also refers to the paintings done in this medium(Sony VGN-FZ190 battery). Tempera paintings are very long lasting, and examples from the first centuries AD still exist. Egg tempera was a primary method of painting until after 1500 when it was superseded by the invention of oil painting. A paint which is commonly called tempera (although it is not) consisting of pigment and glue size is commonly used and referred to by some manufacturers in America as poster paint(Sony VGN-FZ190E battery).

Water miscible oil paint

Water miscible oil paints (also called "water soluble" or "water-mixable") is a modern variety of oil paint which is engineered to be thinned and cleaned up with water, rather than having to use chemicals such as turpentine. It can be mixed and applied using the same techniques as traditional oil-based paint(Sony VGN-FZ18 battery), but while still wet it can be effectively removed from brushes, palettes, and rags with ordinary soap and water. Its water solubility comes from the use of an oil medium in which one end of themolecule has been altered to bind loosely to water molecules, as in a solution(Sony Vaio VGN-FZ21E battery ).

Painting styles

Style is used in two senses: It can refer to the distinctive visual elements, techniques and methods that typify an individual artist's work. It can also refer to the movementor school that an artist is associated with. This can stem from an actual group that the artist was consciously involved with or it can be a category in which art historians have placed the painter(Sony Vaio VGN-FZ21S battery). The word 'style' in the latter sense has fallen out of favor in academic discussions about contemporary painting, though it continues to be used in popular contexts. Such movements or classifications include the following:

Western

Modernism

Modernism describes both a set of cultural tendencies and an array of associated cultural movements(Sony VGN-FZ230E battery), originally arising from wide-scale and far-reaching changes to Western society in the late 19th century and early 20th century. Modernism was a revolt against the conservative values of realism. The term encompasses the activities and output of those who felt the "traditional" forms of art, architecture, literature, religious faith(Sony Vaio VGN-FZ210CE battery), social organization and daily life were becoming outdated in the new economic, social and political conditions of an emerging fully industrialized world. A salient characteristic of modernism is self-consciousness. This often led to experiments with form, and work that draws attention to the processes and materials used (and to the further tendency of abstraction) (Sony Vaio VGN-FZ18S battery).

Impressionism

The first example of modernism in painting was impressionism, a school of painting that initially focused on work done, not in studios, but outdoors (en plein air). Impressionist paintings demonstrated that human beings do not see objects, but instead see light itself(Sony VGN-FW11 battery). The school gathered adherents despite internal divisions among its leading practitioners, and became increasingly influential. Initially rejected from the most important commercial show of the time, the government-sponsored Paris Salon, the Impressionists organized yearly group exhibitions in commercial venues during the 1870s and 1880s(Sony VGN-FW11M battery), timing them to coincide with the official Salon. A significant event of 1863 was the Salon des Refuses, created by Emperor Napoleon III to display all of the paintings rejected by the Paris Salon.

Abstract styles

Abstract painting uses a visual language of form, color and line to create a composition which may exist with a degree of independence from visual references in the world. Abstract expressionism was an (Sony VGN-FZ18L battery)American post-World War II art movement which had a combination of the emotional intensity and self-denial of the German Expressionists with the anti-figurative aesthetic of the European abstract schools such asFuturism, the Bauhaus and Synthetic Cubism and the image of being rebellious, anarchic, highly idiosyncratic and, some feel, nihilistic(Sony Vaio VGN-FZ31B battery).

Action painting, sometimes called "gestural abstraction", is a style of painting in which paint is spontaneously dribbled, splashed or smeared onto the canvas, rather than being carefully applied. The resulting work often emphasizes the physical act of painting itself as an essential aspect of the finished work or concern of its artist(Sony VGN-FZ145E battery). The style was widespread from the 1940s until the early 1960s, and is closely associated with abstract expressionism (some critics have used the terms "action painting" and "abstract expressionism" interchangeably).

Other modernist styles include:

Expressionism

Cubism

Pop art

Other styles

Outsider art

The term outsider art was coined by art critic Roger Cardinal in 1972 as an English synonym for art brut (French:, "raw art" or "rough art")(Sony Vaio VGN-FZ31J battery ), a label created by French artist Jean Dubuffet to describe artcreated outside the boundaries of official culture; Dubuffet focused particularly on art by insane-asylum inmates. Outsider art has emerged as a successful art marketing category (an annual Outsider Art Fair has taken place in New York since 1992) (Sony VGN-FZ72B battery). The term is sometimes misapplied as a catch-all marketing label for art created by people outside the mainstream "art world," regardless of their circumstances or the content of their work.

Photorealism

Photorealism is the genre of painting based on using the camera and photographs to gather information and then from this information(Sony VGN-FZ71B battery), creating a painting that appears to be very realistic like a photograph. The term is primarily applied to paintings from the United States art movement that began in the late 1960s and early 1970s. As a full-fledged art movement, Photorealism evolved from Pop Art and as a counter toAbstract Expressionism(Sony VGN-FZ70B battery).

Hyperrealism is a genre of painting and sculpture resembling a high-resolution photograph. Hyperrealism is a fully fledged school of art and can be considered an advancement of Photorealism by the methods used to create the resulting paintings or sculptures(Sony VGN-FZ62B battery). The term is primarily applied to an independent art movement and art style in the United States and Europe that has developed since the early 2000s.

Surrealism

Surrealism is a cultural movement that began in the early 1920s, and is best known for the visual artworks and writings of the group members. Surrealist artworks feature the element of surprise, unexpected juxtapositions and non sequitur(Sony VGN-FZ140E battery); however, many Surrealist artists and writers regard their work as an expression of the philosophical movement first and foremost, with the works being an artifact. Leader André Breton was explicit in his assertion that Surrealism was above all a revolutionary movement(Sony Vaio VGN-FZ21J battery) .

Surrealism developed out of the Dada activities of World War I and the most important center of the movement was Paris. From the 1920s onward, the movement spread around the globe, eventually affecting thevisual arts, literature, film and music of many countries and languages, as well as political thought and practice, philosophy and social theory(Sony VGN-FZ430E battery).

Allegory

Allegory is a figurative mode of representation conveying meaning other than the literal. Allegory communicates its message by means of symbolic figures, actions or symbolic representation. Allegory is generally treated as a figure of rhetoric, but an allegory does not have to be expressed in language: it may be addressed to the eye(Sony VGN-FZ11E battery), and is often found in realistic painting. An example of a simple visual allegory is the image of the grim reaper. Viewers understand that the image of the grim reaper is a symbolic representation of death.

Bodegon

In Spanish art, a bodegón is a still life painting depicting pantry items, such as victuals, game, and drink(Sony VGP-BPS13B/B battery), often arranged on a simple stone slab, and also a painting with one or more figures, but significant still life elements, typically set in a kitchen or tavern. Starting in the Baroque period, such paintings became popular in Spain in the second quarter of the 17th century(Sony VGP-BPS13A/B battery). The tradition of still life painting appears to have started and was far more popular in the contemporary Low Countries, today Belgium and Netherlands (then Flemish and Dutch artists), than it ever was in southern Europe. Northern still lifes had many sub-genre's; the breakfast piece was augmented by the trompe-l'oil(Sony VGP-BPS13/S battery), the flower bouquet , and the vanitas. In Spain there were much fewer patrons for this sort of thing, but a type of breakfast piece did become popular, featuring a few objects of food and tableware laid on a table.

Body painting

Body painting is a form of body art. Unlike tattoo and other forms of body art, body painting is temporary, painted onto the human skin(Sony VGP-BPS13/B battery), and lasts for only several hours, or at most (in the case of Mehndi or "henna tattoo") a couple of weeks. Body painting that is limited to the face is known as face painting. Body painting is also referred to as (a form of) temporary tattoo; large scale or full-body painting is more commonly referred to as body painting(Sony PCGA-BP2EA battery), while smaller or more detailed work is generally referred to as temporary tattoos.

Figure painting

Figure painting is a form of the visual arts in which the artist uses a live model as the subject of a two-dimensional piece of artwork using paint as the medium(Sony VGP-BPS13AS battery). The live model can be either nude or partly or fully clothed and the painting is a representation of the full body of the model. It is analogous in most respects to figure drawing, which is usually done in crayon, ink, pencil, watercolor or mixed media on paper. Some artists well known for figure painting are Peter Paul Rubens, Edgar Degas, and Édouard Manet(Sony VGP-BPS13S battery).

Illustration painting

Illustration paintings are those used as illustrations in books, magazines, and theater or movie posters and comic books. Today, there is a growing interest in collecting and admiring the original artwork. Various museum exhibitions, magazines and art galleries have devoted space to the illustrators of the past(Sony VGP-BPS13B/S battery).In the visual art world, illustrators have sometimes been considered less important in comparison with fine artists and graphic designers. But as the result of computer game and comic industry growth, illustrations are becoming valued as popular and profitable art works that can acquire a wider market than the other two, especially in Korea, Japan, Hong Kong and USA(Sony VGP-BPS13A/S battery).

Landscape painting

Landscape painting is a term that covers the depiction of natural scenery such as mountains, valleys, trees, rivers, and forests, and especially art where the main subject is a wide view, with its elements arranged into a coherent composition. In other works landscape backgrounds for figures can still form an important part of the work(Sony VGN-FW31J battery). Sky is almost always included in the view, and weather is often an element of the composition. Detailed landscapes as a distinct subject are not found in all artistic traditions, and develop when there is already a sophisticated tradition of representing other subjects(Sony VGP-BPS21 battery). The two main traditions spring from Western painting and Chinese art, going back well over a thousand years in both cases.

Portrait painting

Portrait paintings are representations of a person, in which the face and its expression is predominant. The intent is to display the likeness, personality, and even the mood of the person(Sony VGP-BPS21B battery). The art of the portrait flourished in Ancient Greek and especially Roman sculpture, where sitters demanded individualized and realistic portraits, even unflattering ones. One of the best-known portraits in the Western world is Leonardo da Vinci's painting titled Mona Lisa, which is a painting of an unidentified woman(Sony VAIO PCG-5G2L battery).

Still life

A still life is a work of art depicting mostly inanimate subject matter, typically commonplace objects which may be either natural (food, flowers, plants, rocks, or shells) or man-made (drinking glasses, books, vases, jewelry, coins, pipes, and so on). With origins in the Middle Ages and Ancient Greek/Roman art(Sony VAIO PCG-5G3L battery), still life paintings give the artist more leeway in the arrangement of design elements within a composition than do paintings of other types of subjects such as landscape or portraiture. Still life paintings, particularly before 1700, often contained religious and allegorical symbolism relating to the objects depicted(Sony VAIO PCG-5J1L battery). Some modern still life breaks the two-dimensional barrier and employs three-dimensional mixed media, and uses found objects, photography, computer graphics, as well as video and sound.

Veduta

A Veduta is a highly detailed, usually large-scale painting of a cityscape or some other vista(Sony VAIO PCG-5J2L battery). This genre of landscape originated in Flanders, where artists such as Paul Brill painted vedute as early as the 16th century. As the itinerary of the Grand Tour became somewhat standardized, vedute of familiar scenes like the Roman Forum or the Grand Canal recalled early ventures to the Continent for aristocratic Englishmen(Sony VAIO PCG-5K2L battery). In the later 19th century, more personal "impressions" of cityscapes replaced the desire for topographical accuracy, which was satisfied instead by painted panoramas.

Vacuum cleaner

A vacuum cleaner, commonly referred to as a vacuum is a device that uses an air pump to create a partial vacuum to suck up dust and dirt, usually from floors, and optionally from other surfaces as well(SONY VGP-BPS8 battery). The dirt is collected by either a dustbag or a cyclone for later disposal. Vacuum cleaners, which are used in homes as well as inindustry, exist in a variety of sizes and models: from small battery-operated hand-held devices, huge stationary industrial appliances that can handle several hundred litres of dust before being emptied(SONY VAIO VGN-FZ Battery), and self-propelled vacuum trucks for recovery of large spills or removal of contaminated soil.

History

The vacuum cleaner evolved from the carpet sweeper via manual vacuum cleaners. The first manual models, using bellows, came in the 1860s, and the first motorised models came in the beginning of the 20th century(SONY VAIO VGN-FZ11S Battery).

Daniel Hess

Daniel Hess of West Union, Iowa, USA invented a vacuum cleaner in 1860. Calling it a carpet sweeper instead of a vacuum cleaner, his machine did, in fact, have a rotating brush like a traditional vacuum cleaner, and also possessed an elaborate bellows mechanism on top of the body to generate suction of dust and dirt(SONY vgp-bps9 battery). Hess received a patent (U.S. No. 29.077) for his invention of the vacuum cleaner on July 10, 1860.

Ives W. McGaffey

The first manually-powered cleaner using vacuum principles was the "Whirlwind," invented in Chicago, USA in 1868 by Ives W. McGaffey(sony vgp-bpl9 battery). The machine was lightweight and compact, but was difficult to operate because of the need to turn a hand crank at the same time as pushing it across the floor. McGaffey enlisted the help of The American Carpet Cleaning Co. of Boston to market it to the public. It was sold for $25(SONY VAIO VGN-FZ32 Battery). It is hard to determine how successful the Whirlwind was, as most of them were sold in Chicago and Boston, and it is likely that many were lost in the Great Chicago Fire of 1871. Only two are known to have survived, one of which can be found in the Hoover Historical Center(SONY VAIO VGN-FZ440N Battery).

McGaffey was but one of many 19th-century inventors in the United States and Europe who devised manual vacuum cleaners. He obtained a patent (U.S. No. 91,145) on June 8, 1869(SONY VAIO VGN-FZ280E Battery).

Melville Bissell

In 1876, Melville Bissell of Grand Rapids, Michigan, USA created a vacuum cleaner for his wife, Anna, to clean up sawdust in carpeting. Shortly after, Bissell Carpet Sweepers were born. After Melville died unexpectedly in 1889, Anna took control of the company and was one of the most powerful businesswomen of the day(SONY VAIO VGN-FZ460E Battery).

John S. Thurman

On November 14, 1898, John S. Thurman of St. Louis, Missouri, USA. submitted for patent (U.S. No. 634,042) a "pneumatic carpet renovator". It was issued on October 3, 1899.[5] Thurman created a gasoline powered carpet cleaner for the General Compressed Air Company. In a newspaper advertisement from the St. Louis Dispatch, Thurman offered his invention of the horse drawn (SONY VAIO VGN-FZ190 Battery) (which went door to door) motorized cleaning system in St. Louis. He offered cleaning services at $4 per visit. By 1906, Thurman was offering built-in central cleaning systems that used compressed air, yet featured no dust collection(SONY VAIO VGN-FZ150E Battery). Thurman's machine is sometimes considered the first vacuum cleaner. However, the dust was blown into a receptacle rather than being sucked in, as in the machine now used. In later patent litigation, Judge Augustus Handruled that Thurman "does not appear to have attempted to design a vacuum cleaner, or to have understood the process of vacuum cleaning." (SONY VAIO VGN-FZ260E Battery)

H. Cecil Booth

Hubert Cecil Booth has the strongest claim to inventing the motorized vacuum cleaner in 1901. As Booth recalled decades later, in 1901 he attended “a demonstration of an American machine by its inventor” at the Empire Music Hall in London. The inventor is not named(SONY VAIO VGN-FZ140E Battery), but Booth’s description of the machine conforms fairly closely to Thurman’s design, as modified in later patents. Booth watched a demonstration of the device which blew dust off the chairs, and thought it would be much more useful to have one that sucked dust. He tested the idea by laying a handkerchief on the seat of a restaurant chair, putting his mouth to the handkerchief, and then trying to suck up as much dust as he could onto the handkerchief(SONY VAIO VGN-FZ11l Battery). Upon seeing the dust and dirt collected on the underside of the handkerchief he realized the idea could work.

Booth created a large device, driven first by an oil engine, and later by an electric motor. Nicknamed the "Puffing Billy", Booth's petrol-powered(SONY VAIO VGN-FZ11z Battery), horse-drawn vacuum cleaner relied upon air drawn through a cloth filter. Gaining the royal seal of approval, Booth's motorized vacuum cleaner was used to clean the carpets of Westminster Abbey prior to Edward VII's coronation in 1901. Booth received his first patents on February 18 and August 30, 1901(SONY VAIO VGN-FZ11m Battery).

Booth started the British Vacuum Cleaner Company and refined his invention over the next several decades. Though his "Goblin" model lost out to competition from Hoover in the household vacuum market, his company successfully turned its focus to the industrial market, building ever-larger models for factories and warehouses(SONY VAIO VGN-FZ18m Battery). Booth's company, now BVC, lives on today as a unit of pneumatic tube system maker Quirepace Ltd.

Booth gave the vacuum cleaner its start. His first vacuum cleaner, called "puffin' Billy," was made of a piston pump. It did not contain any brushes; all the cleaning was done by suction through long tubes with nozzles on the ends. It was a large machine, mounted in a horse-drawn van that was pulled through the streets(SONY VAIO VGN-FZ21m Battery). The vans of the British Vacuum Cleaning Company (BVCC) were bright red; uniformed operators would haul hose off the van and route it through the windows of a building to reach all the rooms inside(SONY VAIO VGN-FZ410 Battery). Booth was harassed by complaints about the noise of his vacuum machines and was even fined for frightening horses. The BVCC's most prestigious engagement was cleaning the carpets in Westminster Abbey in London before the 1901 coronation of King Edward VII and Queen Alexandra(SONY VAIO VGN-FZ21 Battery).

David T. Kenney

Nine patents granted to the New Jersey, USA inventor David T. Kenney between 1903 and 1913 established the foundation for the American vacuum cleaner industry. Membership in the Vacuum Cleaner Manufacturers' Association, formed in 1919, was limited to licensees under his patents(SONY VAIO VGN-FZ160 Battery).

Walter Griffiths

In 1905 "Griffith's Improved Vacuum Apparatus for Removing Dust from Carpets" was another manually operated cleaner, patented by Walter Griffiths Manufacturer, Birmingham, England. It was portable, easy to store, and powered by "any one person (such as the ordinary domestic servant) (SONY VAIO VGN-FZ210CE Battery)," who would have the task of compressing a bellows-like contraption to suck up dust through a removable, flexible pipe, to which a variety of shaped nozzles could be attached. This was arguably the first domestic vacuum-cleaning device to resemble the modern vacuum cleaner(SONY VAIO VGN-FZ38M Battery).

Hermann Bogenschild

German immigrant engineer Hermann Bogenschild filed a patent in 1906 for a mechanical 'dust removing apparatus.' Emigrating from Berlin to Milwaukee in 1892, Bogenschild's device was mounted on wheels for portability and its motor was connected to a hose and filter system(SONY VAIO VGN-FZ31z Battery).

James Murray Spangler

In 1907, James Murray Spangler, a janitor from Canton, Ohio, USA invented the first practical, portable vacuum cleaner. Crucially, in addition to suction that used an electric fan, a box, and one of his wife's pillowcases, Spangler's design incorporated a rotating brush to loosen debris(Sony Vaio VGN-FZ31S battery). Unable to produce the design himself due to lack of funding, he sold the patent in 1908 to William Henry Hoover who had Spangler's machine redesigned with a steel casing, casters, and attachments. Subsequent innovations included the first disposal filter bags in the 1920s and the first upright vacuum cleaner in 1926(SONY VAIO VGN-FZ31E Battery).

Hoover

Spangler patented his rotating-brush design June 2, 1908, and eventually sold the idea to his cousin's husband, Hoover. He was looking for a new product to sell, as the leather goods produced by his 'Hoover Harness and Leather Goods' company were becoming obsolete, because of the invention of the automobile(SONY VAIO VGN-FZ31J Battery). In the United States, Hoover remains one of the leading manufacturers of household goods, including vacuum cleaners; and Hoover became very wealthy from the invention. Indeed, in Britain the name Hoover became synonymous with the vacuum cleaner so much so that one "hoovers one's carpets"(SONY VAIO VGN-FZ31M Battery). Initially called 'The Electric Suction Sweeper Company', their first vacuum was the 1908 Model O, which sold for $60.

Constellation

Hoover is also notable for an unusual vacuum cleaner, the Hoover Constellation, which is a cylinder type but lacks wheels. Instead, the vacuum cleaner floats on its exhaust, operating as a hovercraft, although this is not true of the earliest models(SONY VAIO VGN-FZ31B Battery). They had a swivel top hose with the intention being that the user would place the unit in the center of the room, and work around the cleaner. Introduced in 1952, they are collectible, and are easily identified by the spherical shape of the housing. They tended to be loud, had poor cleaning power, and could not float over carpets(HP PAVILION DV6000 battery). But they remain an interesting machine; restored, they work well in homes with lots of hardwood floors.

The Constellations were changed and updated over the years until discontinued in 1975. These Constellations route all of the exhaust under the vacuum using a different airfoil. The updated design is quiet even by modern standards(SONY VGP-BPS13 Battery), particularly on carpet as it muffles the sound. These models float on carpet or bare floor—although on hard flooring, the exhaust air tends to scatter any fluff or debris around.

Hoover has now re-released an updated version of this later model Constellation in the US (model # S3341 in Pearl White and # S3345 in stainless steel) (SONY VGP-BPS13B/B Battery). Changes include a HEPA filtration bag, a 12 amp motor, a suction turbine powered rotating brush floor head, and a redesigned version of the handle, which tended to break. This same model was marketed in the UK under the Maytag brand as the Satellite because of licensing restrictions(ASUS EEE PC battery).

The 5.2 amp motor on older US units provides respectable suction but they all lack a motorized brush head. Therefore they generally work better on hard floors or short pile rugs. Old units take Hoover type J paper bags but the slightly smaller type S allergen filtration bags can be easily trimmed to fit the retaining notches on the old vacuums. Replacement motors are still available from Hoover US for some models(ASUS EEE PC900 battery).

Hoover made another hovering vacuum cleaner model called the Celebrity in 1973. It has a flattened "flying saucer" shape. Hoover added wheels to it make it a conventional cylinder model after a brief run as a hovering vacuum. It uses "Type H" bags(Dell INSPIRON 1525 battery).

Nilfisk

In 1910, P.A. Fisker patented a vacuum cleaner using a name based on the company’s telegram address—Nilfisk. It was the first electric vacuum cleaner in Europe. His design weighed just 17.5 kg and could be operated by a single person. The company Fisker and Nielsen was formed just a few years before. Today the Nilfisk vacuums are delivered by Nilfisk-Advance(Dell INSPIRON E1505 battery).

Electrolux Model V

The first vacuum cleaners were bulky stand-up units and not easily portable. But in 1921 Electrolux launched the Model V, that was designed to lie on the floor on two thin metal runners. This innovation, conceived by Electrolux founder Axel Wenner-Gren, became a standard feature on generations of future vacuum cleaners(Dell INSPIRON 1420 battery).

There is a recorded example of a 1930s Electrolux vacuum cleaner surviving in use for over 70 years, finally breaking in 2008.

Post-World War II

For many years after their introduction, vacuum cleaners remained a luxury item; but after World War II they became common among the middle classes(Dell INSPIRON 1520 battery). They tend to be more common in Western countries because, in most parts of the world, wall-to-wall carpetingis uncommon and homes have tile orhardwood floors, which are easily swept, wiped, or mopped.

Cyclonic vacuums

Vacuum cleaners working on the cyclone principle became popular in the 1990s, although some companies (notably Filter Queen and Regina) (Dell INSPIRON 1464 battery) have been making vacuum cleaners with cyclonic action since 1928. Modern cyclonic cleaners were adapted from industrial cyclonic separators by British designer James Dyson in 1985. He launched his cyclone cleaner first in Japan in the 1980s at a cost of about US$1,800 and later the Dyson DC01 upright in the UK in 1993 for £200(Dell INSPIRON 1564 battery). It was expected that people would not buy a vacuum cleaner at twice the price of a normal cleaner, but it later became the most popular cleaner in the UK. Cleveland's P.A. Geier Company obtained a patent on a cyclonic vacuum cleaner in 1928, which was sold to Health-Mor in 1939 (see http://www.fundinguniverse.com/company-histories/HMI-Industries-Inc-Company-History.html). Filter Queen vacuums use cyclonic action(Dell INSPIRON 1764 battery).

Cyclonic cleaners do not use filtration bags. Instead, the dust is separated in a detachable cylindrical collection vessel or bin. Air and dust are blown at high speed into the collection vessel at a direction tangential to the vessel wall(Dell N3010 Battery), creating a fast-spinning vortex. The dust particles and other debris move to the outside of the vessel bycentrifugal force, where they fall due to gravity. In central or fixed-installation vacuum cleaners, the cleaned air may be exhausted directly outside without need for further filtration(SONY VGP-BPS13/B Battery).

In portable models, the cleaned air from the center of the vortex is expelled from the machine after passing through a number of successively finer filters at the top of the container. The first filter is intended to trap particles which could damage the subsequent filters that remove fine dust particles(Sony VAIO VGN-FZ15T Battery). The filters must regularly be cleaned or replaced to ensure that the machine continues to perform efficiently. Since Dyson, several other companies have introduced cyclone models, including Hoover, Bisell, Eureka, Electrolux, etc. and the cheapest models are no more expensive than a conventional cleaner(Sony VAIO VGN-FZ15G Battery).

Robotic vacuums

In early 2000 several companies developed robotic vacuum cleaners. Some examples are Roomba, Robomaxx, Intellibot, Trilobiteand FloorBot. These machines propel themselves in patterns across a floor, cleaning surface dust and debris into their dustbin. They usually can navigate around furniture and find their recharging stations(SONY VGP-BPS13A/S Battery). Most robotic vacuum cleaners are designed for home use, although there are more capable models for operation in offices, hotels, hospitals, woodshops, etc. Most models are equipped with motorised brushes that sweep debris from the floor into a collection bin. Additionally(SONY VGP-BPS13AS Battery), some such as the Roomba are equipped with an impeller motor to create an actual vacuum, to collect finer dust particles. By the end of 2003 about 570,000 units were sold worldwide.

Other recent developments(SONY VGP-BPS13S Battery)

In 2004 a British company released Airider, a hovering vacuum cleaner that floats on a cushion of air. It has claimed to be light weight and easier to maneuver (compared to using wheels), although it is not the first vacuum cleaner to do this — the Hoover Constellation predated it by at least 35 years(SONY VGP-BPS13B/S Battery).

Technology

A vacuum's suction is caused by a difference in air pressure. An electric fan reduces the pressure inside the machine. Atmospheric pressure then pushes the air through the carpet and into the nozzle, and so the dust is literally pushed into the bag(SONY VAIO PCG-5G2L battery).

Tests have shown that vacuuming can kill 100% of young fleas and 96% of adult fleas.

A British inventor has developed a new cleaning technology known as Air Recycling Technology which instead of using a vacuum uses an air stream to collect dust from the carpet(SONY VAIO PCG-5G3L battery). This technology was tested by the Market Transformation Programme (MTP) and shown to be more energy efficient than the vacuum method. Although working prototypes exist Air Recycling Technology is not currently used in any production cleaner.

Configurations

Vacuum cleaner types include:

Upright

Upright vacuum cleaners are common in the U.S., Britain and several Commonwealth countries, but very unusual in Continental Europe(SONY VAIO PCG-5J1L battery). They take the form of a cleaning head, onto which a handle and bag are attached. Upright designs usually employ a rotating brushroll or beater bar, which removes dirt through a combination of sweeping and vibration. There are two types of upright vacuums; dirty-fan/direct air (found mostly on commercial vacuums), or clean-air/fan-bypass (found on most of today's vacuums) (SONY VAIO PCG-5K2L battery).

The older of the two designs, direct-fan cleaners have a large impeller (fan) mounted close to the suction opening, through which the dirt passes directly, before being blown into a bag. The motor is often cooled by a separate cooling fan(SONY VAIO PCG-5L1L battery). Because of their large-bladed fans, and comparatively short airpaths, direct-fan cleaners create a very efficient airflow from a low amount of power, and make great carpet cleaners. Their 'above-floor' cleaning power is less efficient, since the airflow is lost when it passes through a long hose(SONY VAIO PCG-5J2L battery).

Fan-bypass uprights have their motor mounted after the bag. Dust is removed from the airstream by the bag, and usually a filter, before it passes through the fan. The fans are smaller, and are usually a combination of several moving and stationary turbines working in sequence to boost power(SONY VAIO PCG-6S2L battery). The motor is cooled by the airstream passing through it. Fan-bypass vacuums are good for both carpet and above-floor cleaning, since their suction does not significantly diminish over the distance of a hose, as it does in direct-fan cleaners. However, their air-paths are much less efficient, and can require more than twice as much power than direct-fan cleaners to achieve the same results(SONY VAIO PCG-6S3L battery).

The least common upright vacuum cleaners use a drive-belt powered by the suction motor to rotate the brush-roll. However, a more common design of dual motor upright is available. In these cleaners, the suction is provided via a large motor, while the brushroll is powered by a separate, smaller motor(SONY VAIO PCG-6V1L battery), which does not create any suction. The brush-roll motor can sometimes be switched off, so hard floors can be cleaned without the brush-roll scattering the dirt. It may also have an automatic cut-off feature, which shuts the motor off if the brush-roll becomes jammed, protecting it from damage(SONY VAIO PCG-6W1L battery).

Cylinder

Cylinder models (in the U.S. also often called canister models) dominate the European market. They have the motor and dust collector (using a bag or bagless) in a separate unit, usually mounted on wheels, which is connected to the vacuum head by a flexible hose. Their main advantage is flexibility(SONY VAIO PCG-7111L battery), as you can attach different heads for different tasks, and maneuverability (the head can reach under furniture and makes it very easy to vacuum stairs and vertical surfaces. Many cylinder models have power heads, as standard or add-on equipment, which contain the same sort of mechanical beaters as in upright units(SONY VAIO PCG-6W3L battery), making them as efficient on carpets as upright models. Such beaters are driven by a separate electric motor or a turbine which uses the suction power to spin the brushroll via a drive belt.

Robotic(SONY VAIO PCG-7113L battery)

Robotic vacuum cleaners are a form of carpet sweeper with limited suction power, which move autonomously, usually in a mostly chaotic pattern ("random bounce"). Some come back to a docking station to charge their batteries, and a few are able to empty their dust containers into the dock as well(SONY VAIO PCG-7133L battery).

Hand-held

Hand-held vacuum cleaners, either battery-operated or mains powered, are also popular for cleaning up smaller spills, such as the Black & Decker DustBuster, introduced in 1979, and the various hand-held models from Dirt Devil, first introduced in 1984. Some battery-powered handheld vacuums are wet/dry rated(SONY VAIO PCG-7Z1L battery); the appliance must be partially disassembled and cleaned after picking up wet materials, to avoid developing unpleasant odours.

Drum

Drum models are essentially heavy-duty industrial versions of cylinder vacuum cleaners, where the cylinder consists of a large vertically positioned drum, which can be stationary or on wheels. These models, which can store over 200 litres (53 US gallons), are often hooked up to compressed air and utilize the venturi effect(SONY VAIO PCG-7Z2L battery).

Wet/Dry

Wet or wet/dry or shop vacuum cleaners are a specialized form of the cylinder/drum models that can be used to clean up wet or liquid spills. They commonly can accommodate both wet and dry soilage; some are also equipped with a switch or exhaust port for reversing the airflow, a useful function for everything from clearing a clogged hose to blowing dust into a corner for easy collection(SONY VAIO PCG-8Y1L battery).

Pneumatic

Pneumatic or pneumatic wet/dry vacuum cleaners are a specialized form of wet/dry models that hook up to compressed air. They commonly can accommodate both wet and dry soilage, a useful feature in industrial plants and manufacturing facilities(SONY VAIO PCG-8Y2L battery).

Backpack

Backpack vacuum cleaners are commonly used for commercial cleaning: they allow the user to move rapidly about a large area. They are essentially cylinder vacuum cleaners strapped on the user's back(SONY VAIO PCG-8Z2L battery).

Central

Central vacuum cleaners, also known as built-in or ducted, are a type of cylinder models which have the motor and bag unit located in a central location in the building and provide vacuum inlets throughout the building. Only the hose and head need be carried from room to room, and the hose is commonly 8 m (25 ft) long(SONY VAIO PCG-8Z1L battery), allowing a large range of movement without changing vacuum inlets. Plastic or metal piping connects the inlets to the central unit. The vacuum head may be unpowered, or have beaters operated by an electric motor or by an air-driven turbine(SONY VAIO PCG-7112L battery).

The dirt bag or collection bin in a central vacuum system is usually so large that emptying or changing needs to be done less often, perhaps once per year for an ordinary household. The central unit usually stays in stand-by, and is turned on by a switch on the handle of the hose(SONY VAIO PCG-6W2L battery). Alternately, the unit powers up when the hose is plugged into the wall inlet, when the metal hose connector makes contact with two prongs in the wall inlet and control current is transmitted through low voltage wires to the main unit. A central vacuum typically produces greater suction than common vacuum cleaners, because a larger fan and more powerful motor can be used when they are not required to be portable(SONY VAIO PCG-5K1L battery).

Another benefit of a central vacuum system is that unlike a standard vacuum cleaner, which blows some of the dirt collected back into the room being cleaned (no matter how efficient its filtration), a central vacuum removes all the dirt collected to the central unit(SONY pcga-bp2ea battery). Since this central unit is usually located outside the living area, no dust is recirculated back into the room being cleaned. Also it is possible on most newer models to vent the exhaust entirely outside, even with the unit inside the living quarters(SONY VGP-BPS21A/B Battery).

In addition, because of the remote location of the motor unit, there is much less noise in the room being cleaned than with a standard vacuum cleaner.

Attachments

Most vacuum cleaners are supplied with various specialized attachments, such as tools, brushes and extension wands, which allow them to reach otherwise inaccessible places or to be used for cleaning a variety of surfaces(SONY VGP-BPS21B Battery). The most common of these tools are:

Hard floor brush (for non-upright models)

Carpeted floor brush (for non-upright models)

Dusting brush

Crevice tool

Upholstery tool

Exhaust filtration

Vacuums by their nature cause dust to become airborne, by exhausting air that is not completely filtered. This can cause health problems since the operator ends up inhaling this dust(SONY VGP-BPS21 Battery). There are several methods manufacturers are using to solve this problem. Some methods may be combined together in a single vacuum. Typically the filter is positioned so that the incoming air passes through it before it reaches the motor. Typically, the filtered air then passes through the motor for cooling purposes(SONY VGP-BPS21/S Battery).

Ordinary vacuum cleaners should never be used to clean up asbestos fibres, even those fitted with a HEPA filter.

Bag: The bag is the typical method to capture the debris vacuumed up. It involves a paper or fabric bag that allows air to pass through, but attempts to trap all dust and debris in the bag. The bag may be disposable, or designed to be cleaned and re-used(SONY Vaio PCG-F305 battery).

Bagless: In non-cyclonic bagless models, the role of the bag is taken by the container and a reusable filter, equivalent to a reusable fabric bag.

Cyclonic separation: Vacuum cleaners employing this method are also bagless. It causes intake air to be cycled or spun so fast that the dust is forced out of the air and falls into a storage bin. The operation is similar to that of a centrifuge(SONY VGP-BPS13A/Q Battery).

Water filtration: First seen commercially in the 1920s in the form of the Newcombe Separator (later to become the Rexair Rainbow), water filtration vacuum cleaners use water as a filter. It forces the intake air to pass through water before it is exhausted. The idea behind this is that wet dust cannot become airborne(SONY VGN NR11Z/T battery). They require the dirty water to be dumped and the machine rinsed out after every use, to prevent unpleasant odors and mold growth.

Ultra fine air filter: Also called HEPA filtered. This method is used as a secondary filter after the air has passed thought the rest of the machine. It is meant to remove any remaining dust that could harm the operator. Some vacuum cleaners also use a charcoal filter to remove odors(SONY VGN NR11Z/S battery).

Specifications

The performance of a vacuum cleaner can be measured by several parameters:

airflow, in cubic feet per minute (CFM or ft³/min) or litres per second (l/s)

air speed, in miles per hour (mph) or metres per second (m/s)

suction, vacuum, or water lift, in inches of water or pascals (Pa)

Other specifications of a vacuum cleaner are:

weight, in pounds (lb) or kilograms (kg)

noise, in decibels (dB)

power cord length and hose length (as applicable)

Performance metrics(SONY VGN NR11M/S battery)

Suction

The suction is the maximum pressure difference that the pump can create. For example, a typical domestic model has a suction of about negative 20 kPa. This means that it can lower the pressure inside the hose from normal atmospheric pressure (about 100 kPa) by 20 kPa(SONY VGN NR11S/S battery). The higher the suction rating, the more powerful the cleaner. One inch of water is equivalent to about 249 Pa; hence, the typical suction is 80 inches (2,000 mm) of water.

Input power

The power consumption of a cleaner, in watts, is often the only figure stated. Many North American vacuum manufacturers only give the current in amperes (e.g. "12 amps") and the consumer is left to multiply that by the line voltage of 120 volts to get the approximate power ratings in watts(SONY VGP-BPS13B/Q Battery). The power does not indicate the effectiveness of the cleaner, only how much electricity it consumes.

Output power

The amount of this power that is converted into airflow at the end of the cleaning hose is sometimes stated, and is measured in airwatts: the units are simply watts; "air" is used to clarify that this is output power, not input electrical power(SONY VGP-BPS13Q Battery).

The airwatt is derived from English units. ASTM International defines the airwatt as 0.117354 * F * S, where F is the rate of air flow in ft3/m and S is the pressure in inches of water. This makes one airwatt equal to 0.9983 watts(SONY Vaio VGN-FW21M Battery).

Knowledge of Refrigerator

A refrigerator (commonly abbreviated as fridge) is a cooling apparatus. The common household appliance comprises a thermally insulatedcompartment and a heat pump—chemical or mechanical means—to transfer heat from it to the external environment (i.e., the room in which it is located) (SONY Vaio VGN-NW Battery), cooling the contents to a temperature below ambient. Cooling is a popular food storage technique in developed countries and works by decreasing the reproduction rate of bacteria. The device is thus used to reduce the rate of spoilage of foodstuffs(SONY Vaio VGN-NW21EF/S Battery).

A refrigerator maintains a temperature a few degrees above the freezing point of water. Optimum temperature range for perishable food storage is 3 to 5 °C (37 to 41 °F). A similar device which maintains a temperature below the freezing point of water is called a "freezer"(SONY Vaio VGN-NW21JF Battery).

The refrigerator is a relatively modern invention among kitchen appliances. It replaced the icebox, which had been a common household appliance for almost a century and a half prior. For this reason, a refrigerator is sometimes referred to as an "icebox"(SONY Vaio VGN-NW21MF Battery).

Freezer

Freezer units are used in households and in industry and commerce. Most freezers operate around 0 °F (−18 °C). Domestic freezers can be included as a separate compartment in a refrigerator, or can be a separate appliance. Domestic freezers are generally upright units resembling refrigerators(SONY Vaio VGN-NW21MF/W Battery), or chests (resembling upright units laid on their backs). Many upright modern freezers come with an ice dispenser built into their door.

Commercial and domestic refrigerators

Commercial fridge and freezer units, which go by many other names, were in use for almost 40 years prior to the common home models. They used toxic gas systems, which occasionally leaked, making them unsafe for home use(SONY Vaio VGN-NW31EF/W Battery). Practical household refrigerators were introduced in 1915 and gained wider acceptance in the United States in the 1930s as prices fell and non-toxic, non-flammable synthetic refrigerants such as Freonor R-12 were introduced. It is notable that while 60% of households in the US owned a refrigerator by the 1930s, it was not until 40 years later, in the 1970s, that the refrigerator achieved a similar level of penetration in the United Kingdom(SONY Vaio VGN-NW21ZF Battery).

Styles of refrigerators

Most households use the freezer on top and refrigerator on bottom style, which has been the basic style since the 1940s.

Traditional style 1940s-present freezer top/refrigerator bottom (although most of the earlier models, some of the cheaper later models, and still some mini-fridges use the 'freezer chest,' or what is known as the 'freezer in the fridge') (SONY Vaio VGN-NW31JF Battery). A separate freezer compartment (e.g. notlocated within the larger refrigerator compartment) became the industry standard during the early- to mid-1960s.

Side by side style – introduced by Amana in 1949 but not popular until 1965–present; left side is freezer and the right is refrigerator(SONY Vaio VGN-NW320F/B Battery).

Top refrigerator/bottom freezer style – mid-1950s – present.

French door style – late 1990s-present. Two French doors for refrigerator and bottom freezer.

In the early-1950s, most refrigerators were white, but from the mid-1950s through present day, designers and manufacturers put color into refrigerators(SONY Vaio VGN-NW320F/TC Battery). In the late-1950s/early-1960s, colors like turquoise and pink were popular, brushed chrome plating (similar to stainless finish) was available on some models from different brands. In the 1970s, common colors were Harvest Gold, Avocado Green and almond(SONY Vaio VGN-NW35E Battery). In the 1980s, black colors were viewed as luxurious. In the late 1990s, stainless steel became stylish, and in 2009, one manufacturer introduced multi-color designs.

Many refrigerators can be blended into the cabinetry of the kitchen with panels that can slide over the doors for a built-in look.

Most home refrigerators weigh between 200 pounds (91 kg) and 450 pounds (200 kg), with some models weighing up to 875 pounds (397 kg) (SONY Vaio VGN-NW11S/S Battery).

History

Before the invention of the refrigerator, icehouses were used to provide cool storage for most of the year. Placed near freshwater lakes or packed with snow and ice during the winter, they were once very common. Natural means are still used to cool foods today. On mountainsides(SONY Vaio VGN-NW11Z/S Battery), runoff from melting snow is a convenient way to cool drinks, and during the winter one can keep milk fresh much longer just by keeping it outdoors.

In the 11th century, the Persian physicist and chemist Ibn Sina (Avicenna) invented the refrigerated coil, which condenses aromaticvapours. This was a breakthrough in distillation technology and he made use of it in his steam distillation process, which requires refrigerated tubing, to produce essential oils(SONY Vaio VGN-NW11S/T Battery).

The first known artificial refrigeration was demonstrated by William Cullen at the University of Glasgow in 1748. Between 1805, when Oliver Evans designed the first refrigeration machine that used vapour instead of liquid, and 1902 when Willis Haviland Carrier demonstrated the first air conditioner(SONY Vaio VGN-NW11Z/T Battery), scores of inventors contributed many small advances in cooling machinery. In-home refrigeration became a reality in 1834 with the invention of the cooling compression system by the American inventor Jacob Perkins. In 1850 or 1851, Dr. John Gorriedemonstrated an ice maker(Dell Latitude E4300 battery).

In 1857, Australian James Harrison developed the world first practical ice making machine and refrigeration system, and it was used in the brewing and meat packing industries of Geelong, Victoria. Ferdinand Carré of France developed a somewhat more complex system in 1859(Dell Latitude 2110 battery). Unlike earlier compression-compression machines, which used air as a coolant, Carré's equipment contained rapidly expanding ammonia. The absorption refrigerator was invented by Baltzar von Platen and Carl Munters from Swedenin 1922, while they were still students at the Royal Institute of Technology in Stockholm(Dell Latitude 2100 battery). It became a worldwide success and was commercialized by Electrolux. Other pioneers included Charles Tellier, David Boyle, and Raoul Pictet. Carl von Linde was the first to patent and make a practical and compact refrigerator.

These home units usually required the installation of the mechanical parts, motor and compressor(Dell Latitude D830 battery), in the basement or an adjacent room while the cold box was located in the kitchen. There was a 1922 model that consisted of a wooden cold box, water-cooled compressor, an ice cubetray and a 9-cubic-foot (0.25 m3) compartment, and cost $714. (A 1922 Model-T Ford cost about $450.) In 1923 Frigidaire introduced the first self-contained unit(Dell LATITUDE D820 battery). About this same time porcelain-covered metal cabinets began to appear. Ice cube trays were introduced more and more during the 1920s; up to this time freezing was not an auxiliary function of the modern refrigerator.

The first refrigerator to see widespread use was the General Electric "Monitor-Top" refrigerator introduced in 1927(Dell Latitude D810 battery), so-called because of its resemblance to the gun turret on the ironclad warship USS Monitor of the 1860s. The compressor assembly, which emitted a great deal of heat, was placed above the cabinet, and surrounded with a decorative ring. Over a million units were produced(Dell LATITUDE D800 battery). As the refrigerating medium, these refrigerators used either sulfur dioxide, which is corrosive to the eyes and may cause loss of vision, painful skin burns and lesions, or methyl formate, which is highly flammable, harmful to the eyes, and toxic if inhaled or ingested. Many of these units are still functional today. These cooling systems cannot legally be recharged with the hazardous original refrigerants if they leak or break down(Dell Latitude D630 battery).

The introduction of Freon in the 1920s expanded the refrigerator market during the 1930s and provided a safer, low-toxicity alternative to previously used refrigerants. Separate freezers became common during the 1940s, the popular term at the time for the unit was a "deep freeze"(Dell Latitude D620 battery). These devices, or "appliances", did not go into mass production for use in the home until after World War II. The 1950s and 1960s saw technical advances like automatic defrosting and automatic ice making. More efficient refrigerators were developed in the 1970s and 1980s, even though environmental issues led to the banning of very effective (Freon) refrigerants(Dell Latitude D610 battery). Early refrigerator models (from 1916) had a cold compartment for ice cube trays. From the late 1920s fresh vegetables were successfully processed through freezing by the Postum Company (the forerunner of General Foods), which had acquired the technology when it bought the rights to Clarence Birdseye's successful fresh freezing methods(Dell Latitude D600 battery).

The first successful application of frozen foods occurred when General Foods heiress Marjorie Merriweather Post (then wife of Joseph E. Davies, United States Ambassador to the Soviet Union) deployed commercial-grade freezers in Spaso House, the US Embassy in Moscow, in advance of the Davies’ arrival(Dell Latitude D520 battery). Post, fearful of the USSR's food processing safety standards, fully stocked the freezers with products from General Foods' Birdseye unit. The frozen food stores allowed the Davies to entertain lavishly and serve fresh frozen foods that would otherwise be out of season(Dell Latitude D510 battery). Upon returning from Moscow, Post (who resumed her maiden name after divorcing Davies) directed General Foods to market frozen product to upscale restaurants.

Home freezers as separate compartments (larger than necessary just for ice cubes), or as separate units, were introduced in the United States in 1940. Frozen foods, previously a luxury item, began to be commonplace(Dell Latitude D505 battery).

General technical explanation

A vapor compression cycle is used in most household refrigerators, refrigerator–freezers and freezers. In this cycle, a circulating refrigerant such as R134a enters a compressor as low-pressure vapor at or slightly above the temperature of the refrigerator interior. The vapor is compressed and exits the compressor as high-pressure superheated vapor(Dell Latitude D500 battery). The superheated vapor travels under pressure through coils or tubes comprising "the condenser", which are passively cooled by exposure to air in the room. The condenser cools the vapor, which liquefies. As the refrigerant leaves the condenser, it is still under pressure but is now only slightly above room temperature(Dell Latitude D430 battery). This liquid refrigerant is forced through a metering or throttling device, also known as an expansion valve (essentially a pin-hole sized constriction in the tubing) to an area of much lower pressure. The sudden decrease in pressure results in explosive-like flash evaporation of a portion (typically about half) of the liquid(Dell Latitude D420 battery). The latent heat absorbed by this flash evaporation is drawn mostly from adjacent still-liquid refrigerant, a phenomenon known as "auto-refrigeration". This cold and partially vaporized refrigerant continues through the coils or tubes of the evaporator unit. A fan blows air from the refrigerator or freezer compartment (Dell Latitude D410 battery) ("box air") across these coils or tubes and the refrigerant completely vaporizes, drawing further latent heat from the box air. This cooled air is returned to the refrigerator or freezer compartment, and so keeps the box air cold(Dell Latitude CPX battery). Note that the cool air in the refrigerator or freezer is still warmer than the refrigerant in the evaporator. Refrigerant leaves the evaporator, now fully vaporized and slightly heated, and returns to the compressor inlet to continue the cycle.

An absorption refrigerator works differently from a compressor refrigerator, using a source of heat(Dell Latitude CPI battery), such as combustion of liquefied petroleum gas, solar thermal energy or an electric heating element. These heat sources are much quieter than the compressor motor in a typical refrigerator. A fan or pump might be the only mechanical moving parts; reliance on convection is considered impractical(Dell Latitude C840 battery).

The Peltier effect uses electricity to pump heat directly; this type of refrigerator is sometimes used for camping, or where noise is not acceptable. They can be totally silent (if they don't include a fan for air circulation) but are less energy-efficient than other methods(Dell Latitude C810 battery).

Other uses of an absorption refrigerator (or "chiller") include large systems used in office buildings or complexes such as hospitals and universities. These large systems are used to chill a brine solution that is circulated through the building(Dell Latitude C800 battery).

Many modern refrigerator/freezers have the freezer on top and the fridge on the bottom. Many ask the question "How does the fridge stay cold if the motor doesn't start when I turn the fridge knob?" This question is answered easily. Most fridge/freezers, with the exception of manual defrost models and/or cheaper models utilize what appears to be two thermostats(Dell Latitude C640 battery). Only the freezer compartment is properly temperature controlled. When the freezer gets too warm, the thermostat starts the refrigeration process and a fan also starts. The air is circulated around the freezer. During this time, the fridge is also getting colder. The fridge temperature control knob is doing nothing to 'control' the temperature(Dell Latitude C610 battery). This knob is only controlling the amount of air that actually flows into the fridge via a damper system. This means that the fridge may become too warm. However, because only enough air is partitioned off to the fridge compartment, the freezer usually re-acquires the set temperature quickly, unless the door is opened(Dell Latitude C600 battery). When a door is opened, either in the fridge or the freezer, the fan stops straight away to prevent excessive frost build up on the freezer's evaporator coil (because this coil is technically cooling two areas). When the freezer reaches temperature, the unit cycles off, no matter what temperature the fridge is at(Dell Latitude C540 battery). Some people recommend setting the fridge to max and the freezer to a point where your fridge food won't freeze.

There are also many complaints about fridge/freezers being kept in garages. One very common complaint is that the freezer is defrosted, but the fridge is not. This occurs when the temperature becomes cool enough to cool the inside of the fridge(Dell Latitude C510 battery). Because the fridge thinks the temperature is ok, it won't start unless warm beverages etc. are added. When this happens, the freezer thaws. It is therefore recommended to keep this type of fridge/freezer in a place where it won't get this cold. If the fridge compartment is the sole temperature controller(Dell Latitude C500 battery), then, due to the design, the unit is likely to run for a longer amount of time, which will in turn keep the freezer very cold.

Modern, computerized refrigerators do not use the damper system. The computers manage fan speed for both compartments (although air is still pumped from the freezer) (Dell Latitude C400 battery).

Other alternatives to the vapor-compression cycle but not in current use include thermionic, vortex tube, air cycle, magnetic cooling, Stirling cycle, Malone refrigeration, acoustic cooling, pulse tube and water cycle systems(Dell Latitude 131L battery).

Features

Newer refrigerators may include:

Automatic defrosting;

A power failure warning, alerting the user by flashing a temperature display. The maximum temperature reached during the power failure may be displayed, along with information on whether the frozen food has defrosted or may contain harmful bacteria(Dell Latitude D400 battery);

Chilled water and ice available from an in-door station, so that the door need not be opened;

Water and Ice Dispensing became available in the 1970s. Also some refrigerators have icemakers built-in so the user doesn't have to use ice trays. Some refrigerators have water chillers and water filtration systems(Dell XPS 1647 battery).

Cabinet rollers that allow the refrigerator to be easily rolled around for easier cleaning;

Adjustable shelves and trays which can be repositioned to suit the user;

A Status Indicator to notify the user when it is time to change the water filter(Dell XPS 1645 battery);

An in-door ice caddy, which relocates the ice-maker storage to the freezer door and saves approximately 60 litres (2 cu ft) of usable freezer space. It is also removable, and helps to prevent ice-maker clogging;

A cooling zone in the refrigerator door shelves. Air from the freezer section is diverted to the refrigerator door, to cool milk or juice stored in the door shelf(Dell XPS 1640 battery).

Early freezer units accumulated ice crystals around the freezing units. This was a result of humidity introduced into the units when the doors to the freezer were opened condensing on the cold parts, then freezing. This frost buildup required periodic thawing ("defrosting") of the units to maintain their efficiency(Dell XPS 16 battery). Manual Defrost (referred to as Cyclic) units are still available. Advances in automatic defrosting eliminating the thawing task were introduced in the 1950s, but are not universal, due to energy performance and cost. These units utilized a counter, that only defrosted the freezer compartment (Freezer Chest) when a specific number of door openings had been made(Dell XPS 13 battery). The units were just a small timer combined with an electrical heater wire which heated the freezer's walls for a short amount of time to remove all traces of frost/frosting. Also, early units featured freezer compartments located within the larger refrigerator(Dell XPS M140 battery), and accessed by opening the refrigerator door, and then the smaller internal freezer door; units featuring an entirely separate freezer compartment were introduced in the early 1960s, becoming the industry standard by the middle of that decade. These older freezer compartments were the main cooling body of the refrigerator(Dell Inspiron Mini 12 battery), and only maintained a temperature of around -6°C, which is suitable for keeping food for a week.

Later advances included automatic ice units and self compartmentalized freezing units.

An increasingly important environmental concern is the disposal of old refrigerators – initially because of the freon coolant damaging the ozone layer(Dell XPS M2010 battery), but as the older generation of refrigerators disappears it is the destruction of CFC-bearing insulation which causes concern. Modern refrigerators usually use a refrigerant called HFC-134a (1,1,1,2-Tetrafluoroethane), which does not deplete the ozone layer, instead of freon. A R-134a is now becoming very uncommon in Europe(Dell XPS M1730 battery). Instead, newer refrigerants are being used instead. The main refrigerant now used is R-600a, or Isobutane. This refrigerant is naturally occurring and therefore has a smaller effect on the atmosphere, if released. There have been some reports of refrigerators exploding, if the refrigerant leaks and comes into contact with a spark(Dell XPS M1710 battery).

Disposal of discarded refrigerators is regulated, often mandating the removal of doors; children playing hide-and-seek have been asphyxiated while hiding inside discarded refrigerators, particularly older models with latching doors(Dell XPS M170 battery). More modern units use a magnetic door gasket which holds the door sealed but can be pushed open from the inside. This gasket was invented by Herman C. Ells Sr.

Types of domestic refrigerators

Domestic refrigerators and freezers for food storage are made in a range of sizes. Among the smallest is a 4 L Peltier fridge advertised as being able to hold 6 cans of beer(Dell XPS M1530 battery). A large domestic fridge stands as tall as a person and may be about 1 m wide with a capacity of 600 L. Some models for small households fit under kitchen work surfaces, usually about 86 cm high. Fridges may be combined with freezers, either stacked with fridge or freezer above, below, or side by side(Dell XPS 1340 battery). A fridge without a frozen food storage compartment may have a small section just to make ice cubes. Freezers may have drawers to store food in, or they may have no divisions (chest freezers).

Fridges and freezers may be free-standing, or built into a kitchen(Dell XPS M1330 battery).

Compressor refrigerators are by far the most common type; they make a noticeable noise.

Absorption refrigerators or thermo-electric Peltier units are used where quiet running is required; Peltier coolers are used in the smallest refrigerators as they have no bulky mechanism(Dell XPS M1210 battery).

Compressor and Peltier refrigerators are powered by electricity; absorption units can be designed to be powered by any heat source. A noticeable difference between the two types is the absence of refrigerant with the Peltier coolers (these use a different method of cooling). But Peltier coolers use more electricity because they are thermodynamically inefficient(Dell INSPIRON MINI 9 battery).

Oil, gas (natural gas or propane) and dual power gas/electricity units are also available (typically found in RV's).

Solar refrigerators and Thermal mass refrigerators are designed to reduce electrical consumption. Solar refrigerators have the added advantage that they do not use refrigerants that are harmful to the environment or flammable(Dell STUDIO 1450 battery). Typical solar designs are absorption refrigerators that use ammonia as the working gas, and employ large mirrors to concentrate sufficient sunlight to reach the temperature required to free gaseous ammonia from the solvent. Most thermal mass refrigerators are designed to use electricity intermittently(Dell VOSTRO 1400 battery). As these units are heavily insulated, cooling load is limited primarily to heat introduced by new items to be refrigerated, and ambient air transfer when the unit is open. Very little power is therefore required if opened infrequently. Refrigeration units for commercial and industrial applications can be made in various size, shape or style to fit customer needs(Dell VOSTRO 1500 battery).

Other specialised cooling mechanisms may be used for cooling, but have not been applied to domestic refrigerators.

Magnetic refrigerators are refrigerators that work on the magnetocaloric effect. The cooling effect is triggered by placing a metal alloy in a magnetic field(Dell XPS M1210 battery).

Acoustic refrigerators are refrigerators that use resonant linear reciprocating motors/alternators to generate a sound which is then converted to heat and cold using compressed helium gas. The heat is descarded and the cold is routed to the refrigerator(Dell XPS M1330 battery).

Energy efficiency

In the past, refrigerators consumed more energy than any other home appliance, but in the last twenty years progress has been made to design, manufacture, and encourage the sale of refrigerators with improved energy efficiency. In the early 1990s a competition was held among the major manufacturers to encourage energy efficiency(Dell XPS 1340 battery). Current models that are Energy Starqualified use 50 percent less energy than the average models made in 1974. The most energy-efficient unit made in the US consumes about half a kilowatt-hour per day. But even ordinary units are quite efficient; some smaller units use less than 0.5 kilowatt-hour per day(Dell XPS M1530 battery).

Larger units, especially those with large freezers and icemakers, may use as much as 4 kW·h per day. The small, mini-fridge (or bar fridge), is an example of bad design. Because these fridges are so small and lacking in large amounts of capacity(Dell XPS M170 battery), when the door is opened a large amount of the cool air escapes, leaving a large amount of warm, moist air for the unit to cool down. This means, if the unit is cycled off when the door is opened, it is likely the unit will start almost as soon as the door is shut.

Among the different styles of refrigerators, top-freezer models are more efficient than bottom-freezer models of the same capacity(Dell XPS M1710 battery), which are in turn more efficient than side-freezer models. Models with through-the-door ice units are less efficient than those without. Dr. Tom Chalko in Australia has developed an external thermostat to convert any chest freezer into a chest fridge using only about 0.1kWh per day—the amount of energy used by a 100 watt light bulb in one hour(Dell XPS M1730 battery) . A similar device is manufactured by Johnson Controls. Scientists at Oxford University have reconstructed a refrigerator invented in 1930 by Leó Szilárd and Albert Einstein in their efforts to replace current technologies with energy efficient green technology(Dell XPS M2010 battery). The Einstein refrigerator operates without electricity and uses no moving parts or greenhouse gases.

Many refrigerators made in the 1930s and 1940s were far more efficient than most that were made later. This is partly attributable to the addition of new features, such as auto-defrost, that reduced efficiency(Dell Inspiron Mini 12 battery). Additionally, post World War 2, refrigerator style became more important than efficiency. This was especially true in the 1970s, when side by side models with ice dispensers and water chillers became popular. However, the reduction in efficiency also comes partly from cost cutting (less insulation). Only now are refrigerators getting back to the energy efficiency of 1930s models, with the introduction of new energy requirements(SONY VGP-BPS9A/S battery)

The efficiency of older refrigerators can be improved by defrosting (if the unit is manual defrost)and cleaning them regularly, replacing old and worn door seals with new ones, adjusting the thermostat to be appropriate to the actual contents (a fridge doesn't need to be colder than 4°C if it is storing drinks and non-perishable items only) (SONY VGP-BPS9/B battery) and also replacing insulation, where applicable. Some sites recommend that you clean the condenser coils every month or so on units that have coils on the rear. It has been proved that this does very little for improving efficiency, however, the unit should be able to 'breathe' with adequate spaces around the front(SONY VGP-BPS9/S battery), back, sides and above the unit. If the refrigerator uses a fan to keep the condenser cool, then this must be cleaned, at the very least, yearly.

Frost Free refrigerators and/or freezers utilize electric fans to cool the appropriate compartment. This could be referred to as a 'Fan Forced' refrigerator, whereas manual defrost units rely on colder air lying at the bottom(SONY VGP-BPS9A battery), versus the warm air at the top to achieve adequate cooling. The air is drawn in through an inlet duct and passed through the evaporator where it is cooled, the air is then circulated through-out the cabinet via a series of ducts and vents. Because the air passing the evaporator is supposedly warm and moist(SONY VGP-BPS9A/B battery), frost begins to form on the evaporator (especially on a freezer's evaporator). In cheaper and/or older models, a defrost cycle was controlled via a mechanical timer. This timer was set to shut off the compressor and fan and energize a heating element located at the base of the evaporate for up to 30 minutes(HP Pavilion DV6-1210SA battery). This melted any frost or ice build up and allowed the refrigerator to work normally once more. It is believed that frost free units have a lower tolerance for frost, due to their air-conditioner like evaporator coils. Therefore, if a door is left open accidentally (especially the freezer) (SONY VGP-BPS11 battery), the defrost system may not remove all frost, in this case, the freezer (or fridge) must be defrosted.

If the defrosting system melts all the ice before the timed defrosting period ends, then a small device (called a Defrost Terminator) acts like a thermostat and shuts off the heating element to prevent too large a temperature fluctuation(SONY VGP-BPL11 battery), it also prevents hot blasts of air when the system starts again, should it finish defrosting early. When the 30 minutes or so defrost is completed, the compressor and fan are allowed to cycle back on if necessary.

Single frost free fridge units that are frost free generally don't shut off their fans whilst defrosting(SONY VGP-BPL12 battery). This allows consumers to leave food in the main fridge compartment uncovered, and also helps keep any vegetables some-what moist. This method also helps reduce energy consumption, because a fridge is above freeze point, the warmer than freezing air can be passed through the evaporator to aid the defrosting cycle. The less time the electric heater element is left on, the lower the energy consumption(SONY VGP-BPS12 battery).

Regarding total life-cycle costs, many governments offer incentives to encourage recycling of old refrigerators. One example is the Phoenix fridge program launched in Australia. This government incentive picked up old refrigerators, paying their owners for 'donating' the fridge(SONY VGP-BPS14 Battery). The fridge was then refurbished, with new door seals, a thorough cleaning and the removal of items, such as the cover that is strapped to the back of many older units. The resulting fridges, now over 10% more efficient, were then distributed to low income families(SONY VGP-BPS14/B Battery).

Impact on lifestyle

The refrigerator allows the modern family to keep food fresh for much longer than before. This, along with the modern supermarket, allows most families, without a sizable garden in which to grow vegetables and raise animals, a vastly more varied diet and improved health resulting from improved nutrition(SONY VGP-BPS14/S Battery). Dairy products, meats, fish, poultry and vegetables can be kept refrigerated in the same space within the kitchen (although raw meat should be kept separate from other foodstuffs for reasons of hygiene) (SONY VGP-BPS14B Battery).

The refrigerator lets people eat more salads, fresh fruits and vegetables, without having to own a garden or an orchard. Exotic foodstuffs from far-off countries that have been imported by means of refrigeration can be enjoyed in the home because of domestic refrigeration(SONY VGP-BPS22 battery).

While allowing more healthy foods to be stored for longer times, more refrigerators and freezers are stocked with processed, quick-cook foods that are less healthy. Studies connecting the correlation between frozen (microwaved) foods and obesity have proven that access to easy meals has led to a general decline in overall health(SONY VGP-BPS18 battery).

Freezers allow households to buy food in bulk: it can be eaten at leisure, and bulk purchase saves money. Ice cream, a popular commodity of the 20th century, could previously only be obtained by traveling long distances to where the product was made fresh, and had to be eaten on the spot(SONY VGP-BPS22/A battery). Now it is a common food item. Ice on demand not only adds to the enjoyment of cold drinks, but is useful for first-aid, and for cold packs that can be kept frozen for picnics or in case of emergency.

Temperature zones and ratings

Some refrigerators are now divided into four zones to store different types of food:

−18 °C (−0 °F) (freezer)

0 °C (32 °F) (meats)

5 °C (41 °F) (refrigerator)

10 °C (50 °F) (vegetables) (SONY VGP-BPS22A battery)

The capacity of a refrigerator is measured in either litres or cubic feet. Typically the volume of a combined fridge-freezer is split to 100 litres (3.53 cubic feet) for the freezer and 140 litres (4.94 cubic feet) for the refrigerator, although these values are highly variable(SONY VGP-BPL10 battery).

Temperature settings for refrigerator and freezer compartments are often given arbitrary numbers by manufacturers (for example, 1 through 9, warmest to coldest), but generally 3 to 5 °C (37 to 41 °F) is ideal for the refrigerator compartment and −18 °C (−0 °F) for the freezer. Some refrigerators are required to be within certain external temperature parameters to run properly(SONY VGP-BPS10 battery). This can be an issue when placing units in an unfinished area such as a garage.

European freezers, and refrigerators with a freezer compartment, have a four star rating system to grade freezers.

* : min temperature = −6 °C (21.2 °F). Maximum storage time for frozen food is 1 week

** : min temperature = −12 °C (10.4 °F). Maximum storage time for frozen food is 1 month

*** : min temperature = −18 °C (−0 °F). Maximum storage time for frozen food is 3 months

*(***) : min temperature = −18 °C (−0 °F). Maximum storage time for frozen food is up to 12 months(Dell Latitude E6500 battery)

Although both the three and four star ratings specify the same minimum temperature of -18°C, only a four star freezer is intended to be used for freezing fresh food. Three (or fewer) stars are used for frozen food compartments which are only suitable for storing frozen food(Dell Latitude E6400 battery); introducing fresh food into such a compartment is likely to result in unacceptable temperature rises. Most European refrigerators include a moist cold fridge section (which does require (automatic) defrosting at irregular intervals) and a (rarely frost free) freezer section(Dell Latitude E5400 battery).

Recycling

Old refrigerators have been adapted to create low cost passive solar water heating systems. Also, many refrigerators have been refurbished for low-income families in eastern Australia via the Phoenix fridge program (see energy efficiency) (SONY VAIO VGN-FZ21E Battery)