Pottery Nursery

Step by step pottery nursery

joannefunfan — Mon, 21 Dec 2009 14:42:49 +0000

Here is a step by step look at how we make pottery. These are the steps we use every day in our studio. The process of making pottery at our studio is basically the same as you will find at any other true pottery studio in the world today. From raw clay to finished product we follow the steps that have been established over the centuries by potters on every continent. Every piece of pottery we make is hand crafted. We do not use the shortcut methods of press moulding, buying bisque ware from outside suppliers, or using mechanical devices to make the pots. Cindy does all the wheel throwing on an electric potter’s wheel and all the slab pottery is built by hand. The only moulding we do is some slump moulding of platters, and even then each is made from a slab rolled on the slab roller and cut by hand before being draped into a mould.

Our clay is purchased from the Plainsman Clay Company which is located in Medicine Hat, Alberta. Plainsman processes clays from Alberta, British Columbia, and Saskatchewan, as well as Montana to provide raw materials for potters all over Western Canada. We work with different clay bodies depending on what we are building and to obtain a bisqued product with which our glazes will fit well. For wheel thrown pottery the red and brown clays are first “pugged” in a pug mill to thoroughly blend them. White clay is simply wedged straight from the box. Our pug mill was made for us by a local machinist and inventor, Guy Ells aka “Moonlight Manufacturing”. This machine is made with two counter-rotating screw augers which take the clay we feed into the hopper and mix it thoroughly, then push it through a single 3″ outlet pipe, accomplishing basically the same action as hand wedging. A good pug mill such as this forces almost all the air out of the clay. (Some more elaborate pug mills have vacuum pumps to try and remove every last bit of air.)

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Cindy demonstrates the use of the pugmill.

The clay is then briefly “wedged” by hand to establish a consistency in the raw materials and align the clay particles and remove any air left over from the pugging process. There are two types of wedging we use. Cindy favours the Japanese style of wedging she is using in this illustration. It enables her to wedge a large amount of clay at once but does require some practice to perfect the technique. A simpler type of wedging, forward or “Cow-head wedging”, is often used by beginning potters as it is easy to do with a minimum of practice.

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Cindy demonstrates wedging the clay.

For slab building pottery we use the clay directly from the pug mill. The pugged clay is flattened by throwing it at an angle on a canvas covered table. It is then placed on a piece of canvas, a second piece of canvas is placed on top of it, and then the canvas and clay “sandwich” is run between the rollers of the slab roller to give a uniform thickness to the clay. (The slab roller is similar in action to the wringers on an old washing machine.)

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The slab is then carried to a table where pieces are cut from it to be hand formed into pottery platters or sushi sets, for example. Once the cut pieces have set for awhile they are easier to form. Sometimes they may be dropped onto or into a form to give them a particular shape. This is called slump moulding.Once the piece has dried to “leather hardness” it is trimmed and sponged and is then ready to completely dry in preparation for the bisque firing.

Cindy Clarke explains briefly some of the tools used when making pottery. This is an excerpt from our 90 minute DVD.

Pottery nursery Basics

joannefunfan — Mon, 21 Dec 2009 14:41:46 +0000

Easier - Pottery are objects that are first shaped of wet clay, then hardened by baking. Pottery includes both decorative and practical items such as bowls, vases, dishes, and lamps.

Harder – Pottery is a decorative or useful ware made of baked clay. Pottery includes valuable works of art, inexpensive dinnerware, vases, and other simple household items, all made by professional potters. The word pottery also refers to the factory that makes pottery. Pottery ware is part of a larger product group called ceramics that encompasses bricks, cement, sewer pipes, and other industrial products. Four steps are needed to make a pottery product: preparing the clay mixture, shaping the clay, decorating and glazing the item, and firing (baking). The firing temperature gives pottery its finished appearance and its strength.
There are three major pottery types: (1) earthenware, (2) stoneware, and (3) porcelain. Each type is distinguished by its clay mixture and the temperature at which it is baked or fired. Earthenware is a pottery clay mixture that is fired at a lower temperature. The low baking temperature allows the use of colorful glazes, but also yields a pottery that cracks and chips more easily than other types. Stoneware pottery is made of a heavier clay mixture that gives it greater strength. Stoneware is fired at a much higher temperature to give a harder finish. Porcelain is the purest and the most delicate type of pottery. It is formed from koalin, a fine white clay, that is mixed with controlled amounts of feldspar and flint and then fired at a low temperature.

Pottery Nursery

joannefunfan — Mon, 21 Dec 2009 14:40:36 +0000

pottery nursery is the ceramic ware made by potters. Major types of pottery nursery include earthenware, stoneware, and porcelain. The places where such wares are made are called potteries. pottery nursery is one of the oldest human technologies and art-forms, and remains a major industry today. Ceramic art covers the art of pottery nursery, whether in items made for use or purely for decoration. Contents * 1 Background * 2 Methods of shaping * 3 Decorating and glazing o 3.1 Glazing * 4 Firing * 5 History * 6 In archaeology * 7 Environmental issues in production * 8 Other usages * 9 See also * 10 Notes * 11 References * 12 External links [edit] Background pottery nursery is made by forming a clay body into objects of a required shape and heating them to high temperatures in a kiln to induce reactions that lead to permanent changes, including increasing their strength and hardening and setting their shape. There are wide regional variations in the properties of clays used by potters and this often helps to produce wares that are unique in character to a locality. It is common for clays and other minerals to be mixed to produce clay bodies suited to specific purposes. Prior to some shaping processes, air trapped within the clay body needs to be removed. This is called de-airing and can be accomplished by a machine called a vacuum pug or manually by wedging. Wedging can also help to ensure an even moisture content throughout the body. Once a clay body has been de-aired or wedged, it is shaped by a variety of techniques. After shaping it is dried before firing. There are a number of stages in the drying process. Leather-hard refers to the stage when the clay object is approximately 75-85% dry. Clay bodies at this stage are very firm and only slightly pliable. Trimming and handle attachment often occurs at the leather-hard state. Clay bodies are said to be “bone-dry” when they reach a moisture content at or near 0%. Unfired objects are often termed greenware. Clay bodies at this stage are very fragile and hence can be easily broken. [edit] Methods of shaping A man shapes pottery nursery as it turns on a wheel. (Cappadocia, Turkey). The potter’s most basic tool is the hand. However, many additional tools have been developed over the long history of pottery nursery manufacturing, including the potter’s wheel and turntable, shaping tools (paddles, anvils, ribs), rolling tools (roulettes, slab rollers, rolling pins), cutting/piercing tools (knives, fluting tools, wires) and finishing tools (burnishing stones, rasps, chamois). pottery nursery can be shaped by a range of methods that include: Handwork pottery nursery in Kathmandu, Nepal. Handwork or hand building. This is the earliest and the most individualized and direct forming method. Wares can be constructed by hand from coils of clay, from flat slabs of clay, from solid balls of clay — or some combination of these. Parts of hand-built vessels are often joined together with the aid of slurry or slip, a runny mixture of clay and water. Hand building is slower and more gradual than wheel-throwing, but it offers the potter a high degree of control over the size and shape of wares. While it isn’t difficult for an experienced potter to make identical pieces of hand-built pottery nursery, the speed and repetitiveness of wheel-throwing is more suitable for making precisely matched sets of wares such as table wares. Some studio potters find hand building more conducive to fully using the imagination to create one-of-a-kind works of art, while others find this with the wheel. PotteryShaping.ogg Play video A potter shapes a piece of pottery nursery on an electric-powered potter’s wheel Classic potter’s kick wheel in Erfurt, Germany The potter’s wheel. In the process that is called “throwing” (coming from the Old English word thrawan, which means to twist or turn [1]) , a ball of clay is placed in the center of a turntable, called the wheel-head, which the potter rotates with a stick, or with foot power (a kick wheel or treadle wheel) or with a variable speed electric motor. (Often, a disk of plastic, wood or plaster — called a bat — is first set on the wheel-head, and the ball of clay is thrown on the bat rather than the wheel-head so that the finished piece can be removed intact with its bat, without distortion.) During the process of throwing the wheel rotates rapidly while the solid ball of soft clay is pressed, squeezed, and pulled gently upwards and outwards into a hollow shape. The first step, of pressing the rough ball of clay downward and inward into perfect rotational symmetry, is called centering the clay, a most important (and often most difficult) skill to master before the next steps: opening (making a centered hollow into the solid ball of clay), flooring (making the flat or rounded bottom inside the pot), throwing or pulling (drawing up and shaping the walls to an even thickness), and trimming or turning (removing excess clay to refine the shape or to create a foot). From around 7th century BC until the introduction of slip casting in the 18th century AD, the potter’s wheel was the most effective method of mass producing pottery nursery, although it is also often employed to make individual pieces. Wheel-work makes great demands on the skill of the potter, but an accomplished operator can make many near-identical plates, vases, or bowls in the course of a day’s work. Because of its inherent limitations, wheel-work can only be used to create wares with radial symmetry on a vertical axis. These can then be altered by impressing, bulging, carving, fluting, faceting, incising, and by other methods making the wares more visually interesting. Often, thrown pieces are further modified by having handles, lids, feet, spouts, and other functional aspects added using the techniques of handworking. Jiggering and jolleying: These operations are carried out on the potter’s wheel and allow the time taken to bring wares to a standardized form to be reduced. Jiggering is the operation of bringing a shaped tool into contact with the plastic clay of a piece under construction, the piece itself being set on a rotating plaster mould on the wheel. The jigger tool shapes one face whilst the mould shapes the other. Jiggering is used only in the production of flat wares, such as plates, but a similar operation, jolleying, is used in the production of hollow-wares, such as cups. Jiggering and jolleying have been used in the production of pottery nursery since at least the 18th century. In large-scale factory production jiggering and jolleying are usually automated, which allows the operations to be carried out by semi-skilled labor. Shaping on a potter’s kick wheel; Gülsehir, Turkey Roller-head machine: This machine is for shaping wares on a rotating mould, as in jiggering and jolleying, but with a rotary shaping tool replacing the fixed profile. The rotary shaping tool is a shallow cone having the same diameter as the ware being formed and shaped to the desired form of the back of the article being made. Wares may in this way be shaped, using relatively unskilled labor, in one operation at a rate of about twelve pieces per minute, though this varies with the size of the articles being produced. The roller-head machine is now used in factories worldwide. RAM pressing: A factory process for shaping table wares and decorative ware by pressing a bat of prepared clay body into a required shape between two porous molding plates. After pressing, compressed air is blown through the porous mould plates to release the shaped wares. Granulate pressing: As the name suggests, this is the operation of shaping pottery nursery by pressing clay in a semi-dry and granulated condition in a mould. The clay is pressed into the mould by a porous die through which water is pumped at high pressure. The granulated clay is prepared by spray-drying to produce a fine and free flowing material having a moisture content of between about five and six per cent. Granulate pressing, also known as dust pressing, is widely used in the manufacture of ceramic tiles and, increasingly, of plates. Slipcasting: is often used in the mass-production of ceramics and is ideally suited to the making of wares that cannot be formed by other methods of shaping. A slip, made by mixing clay body with water, is poured into a highly absorbent plaster mold. Water from the slip is absorbed into the mould leaving a layer of clay body covering its internal surfaces and taking its internal shape. Excess slip is poured out of the mold, which is then split open and the molded object removed. Slipcasting is widely used in the production of sanitary wares and is also used for making smaller articles, such as intricately-detailed figurines. [edit] Decorating and glazing Contemporary pottery nursery from Okinawa, Japan. pottery nursery may be decorated in a number of ways, including: * In the clay body; by, for example, incising patterns on its surface. * Underglaze decoration, in the manner of many blue and white wares. * In-glaze decoration * On-glaze decoration * Enamel Additives can be worked into the clay body prior to forming, to produce desired effects in the fired wares. Coarse additives, such as sand and grog (fired clay which has been finely ground) are sometimes used to give the final product a required texture. Contrasting colored clays and grogs are sometimes used to produce patterns in the finished wares. Colorants, usually metal oxides and carbonates, are added singly or in combination to achieve a desired color. Combustible particles can be mixed with the body or pressed into the surface to produce texture. Agateware: So-named after its resemblance to the quartz mineral agate which has bands or layers of color that are blended together. Agatewares are made by blending clays of differing colors together, but not mixing them to the extent that they lose their individual identities. The wares have a distinctive veined or mottled appearance. The term ‘agateware’ is used to describe such wares in the United Kingdom; in Japan the term neriage is used and in China, where such things have been made since at least the Tang Dynasty, they are called marbled wares. Great care is required in the selection of clays to be used for making agatewares as the clays used must have matching thermal movement characteristics. Banding: This is the application, by hand or by machine, of a band of color to the edge of a plate or cup. Also known as lining, this operation is often carried out on a potter’s wheel. Burnishing: The surface of pottery nursery wares may be burnished prior to firing by rubbing with a suitable instrument of wood, steel or stone, to produce a polished finish that survives firing. It is possible to produce very highly polished wares when fine clays are used, or when the polishing is carried out on wares that have been partially dried and contain little water, though wares in this condition are extremely fragile and the risk of breakage is high. An ancient Armenian urn. Engobe: This is a clay slip, often white or cream in color that is used to coat the surface of pottery nursery, usually before firing. Its purpose is often decorative, though it can also be used to mask undesirable features in the clay to which it is applied. Engobe slip may be applied by painting or by dipping, to provide a uniform, smooth, coating. Engobe has been used by potters from pre-historic times until the present day, and is sometimes combined with sgraffito decoration, where a layer of engobe is scratched through to reveal the color of the underlying clay. With care it is possible to apply a second coat of engobe of a different color to the first and to incise decoration through the second coat to expose the color of the underlying coat. Engobes used in this way often contain substantial amounts of silica, sometimes approaching the composition of a glaze. Litho: This is a commonly used abbreviation for lithography, although the alternative names of transfer print or decal are also common. These are used to apply designs to articles. The litho comprises three layers: the color, or image, layer which comprises the decorative design; the cover coat, a clear protective layer, which may incorporate a low-melting glass; and the backing paper on which the design is printed by screen printing or lithography. There are various methods of transferring the design while removing the backing-paper, some of which are suited to machine application Gold: Decoration with gold is used on some high quality ware. Different methods exist for its application, including: * Best gold – a suspension of gold powder in essential oils mixed with a flux and a mercury salt extended. This can be applied by a painting technique. From the kiln the decoration is dull and requires burnishing to reveal the full color * Acid Gold – a form of gold decoration developed in the early 1860s at the English factory of Mintons Ltd, Stoke-on-Trent. The glazed surface is etched with diluted hydrofluoric acid prior to application of the gold. The process demands great skill and is used for the decoration only of ware of the highest class. * Bright Gold – consists of a solution of gold sulphoresinate together with other metal resonates and a flux. The name derives from the appearance of the decoration immediately after removal from the kiln as it requires no burnishing * Mussel Gold – an old method of gold decoration. It was made by rubbing together gold leaf, sugar and salt, followed by washing to remove solubles [edit] Glazing Main article: Ceramic glaze Glaze is a glassy coating applied to pottery nursery, the primary purposes of which include decoration and protection. Glazes are highly variable in composition but usually comprise a mixture of ingredients that generally, but not always, mature at kiln temperatures lower than that of the pottery nursery that it coats. One important use of glaze is in rendering pottery nursery vessels impermeable to water and other liquids. Glaze may be applied by dusting it over the clay, spraying, dipping, trailing or brushing on a thin slurry composed of glaze minerals and water. Brushing tends not to give an even covering but can be effective as a decorative technique. The color of a glaze before it has been fired may be significantly different than afterwards. To prevent glazed wares sticking to kiln furniture during firing, either a small part of the object being fired (for example, the foot) is left unglazed or, alternatively, special refractory spurs are used as supports. These are removed and discarded after the firing. Special methods of glazing are sometimes carried out in the kiln. One example is salt-glazing, where common salt is introduced to the kiln to produce a glaze of mottled, orange peel texture. Materials other than salt are also used to glaze wares in the kiln, including sulfur. In wood-fired kilns fly-ash from the fuel can produce ash-glazing on the surface of wares, and the use of an ash and clay mix can result in alkaline glazes, as used in Catawba Valley pottery nursery in the eastern United States. [edit] Firing Firing produces irreversible changes in the body. It is only after firing that the article can be called pottery nursery. In lower-fired pottery nursery the changes include sintering, the fusing together of coarser particles in the body at their points of contact with each other. In the case of porcelain, where different materials and higher firing-temperatures are used the physical, chemical and mineralogical properties of the constituents in the body are greatly altered. In all cases the object of firing is to permanently harden the wares and the firing regime must be appropriate to the materials used to make them. As a rough guide, earthenwares are normally fired at temperatures in the range of about 1000 to 1200 degrees Celsius; stonewares at between about 1100 to 1300 degrees Celsius; and porcelains at between about 1200 to 1400 degrees Celsius. However, the way that ceramics mature in the kiln is influenced not only by the peak temperature achieved, but also by the duration of the period of firing. Thus, the maximum temperature within a kiln is often held constant for a period of time to soak the wares, to produce the maturity required in the body of the wares. The atmosphere within a kiln during firing can affect the appearance of the finished wares. An oxidising atmosphere, produced by allowing air to enter the kiln, can cause the oxidation of clays and glazes. A reducing atmosphere, produced by limiting the flow of air into the kiln, can strip oxygen from the surface of clays and glazes. This can affect the appearance of the wares being fired and, for example, some glazes containing iron fire brown in an oxidising atmosphere, but green in a reducing atmosphere. The atmosphere within a kiln can be adjusted to produce complex effects in glaze. Kilns may be heated by burning wood, coal and gas, or by electricity. When used as fuels, coal and wood can introduce smoke, soot and ash into the kiln which can affect the appearance of unprotected wares. For this reason wares fired in wood- or coal-fired kilns are often placed in the kiln in saggars; lidded ceramic boxes, to protect them. Modern kilns powered by gas or electricity are cleaner and more easily controlled than older wood- or coal-fired kilns and often allow shorter firing times to be used. In a Western adaptation of traditional Japanese Raku ware firing, wares are removed from the kiln while hot and smothered in ashes, paper or woodchips, which produces a distinctive, carbonised, appearance. This technique is also used in Malaysia in creating traditional labu sayung. [edit] History Main article: Ceramic art Earliest known ceramics are the Gravettian figurines that date to 29,000 to 25,000 BC Cupisnique pottery nursery. Stirrup spout bottle with a feline-human representation. Larco Museum Collection. Lima-Peru An Incipient Jomon pottery nursery vessel reconstructed from fragments (10,000-8,000 BCE), Tokyo National Museum, Japan It is believed that the earliest pottery nursery wares were hand-built and fired in bonfires. Firing times were short but the peak-temperatures achieved in the fire could be high, perhaps in the region of 900 degrees Celsius, and were reached very quickly. Clays tempered with sand, grit, crushed shell or crushed pottery nursery were often used to make bonfire-fired ceramics, because they provided an open body texture that allows water and other volatile components of the clay to escape freely. The coarser particles in the clay also acted to restrain shrinkage within the bodies of the wares during cooling, which was carried out slowly to reduce the risk of thermal stress and cracking. In the main, early bonfire-fired wares were made with rounded bottoms, to avoid sharp angles that might be susceptible to cracking. The earliest intentionally constructed kilns were pit-kilns or trench-kilns; holes dug in the ground and covered with fuel. Holes in the ground provided insulation and resulted in better control over firing. The earliest known ceramic objects are Gravettian figurines such as those discovered at Dolni Vestonice in the modern-day Czech Republic. The Venus of Dolní Vestonice (Vestonická Venuše in Czech) is a Venus figurine, a statuette of a nude female figure dated to 29,000–25,000 BCE (Gravettian industry).[2] The earliest pottery nursery ware found to date was excavated from the Yuchanyan Cave in southern China and the Proceedings of the National Academy of Sciences in 2009 reports that the ware dates back to 18,000 years ago.[3] pottery nursery vessels made by the Incipient Jomon people of Japan from around 10,500 BCE have also been found.[4][5]. The term “Jomon” means “cord-marked” in Japanese. This refers to the markings made on clay vessels and figures using sticks with cords wrapped around them. pottery nursery which dates back to 10,000 BCE have also been excavated in China.[6] It appears that pottery nursery was independently developed in North Africa during the tenth millennium b.p.[7] and in South America during the seventh millennium b.p.[8] The invention of the potter’s wheel in Mesopotamia sometime between 6,000 and 4,000 BCE (Ubaid period) revolutionized pottery nursery production. Specialized potters were then able to meet the expanding needs of the world’s first cities. pottery nursery was in use in ancient India during the Mehrgarh Period II (5500 – 4800 BCE) and Merhgarh Period III (4800 – 3500 BCE), known as the ceramic Neolithic and chalcolithic. pottery nursery, including items known as the ed-Dur vessels, originated in regions of the Indus valley and has been found in a number of sites in the Indus valley civilization.[9][10] In the Mediterranean, during the Greek Dark Ages (1100–800 BCE), artists used geometric designs such as squares, circles and lines to decorate amphoras and other pottery nursery. The period between 1500-300 BCE in ancient Korea is known as the Mumun pottery nursery Period.[11] The quality of pottery nursery has varied historically, in part dependent upon the repute in which the potter’s craft was held by the community[citation needed]. For example, in the Chalcolithic period in Mesopotamia, Halafian pottery nursery achieved a level of technical competence and sophistication, not seen until the later developments of Greek pottery nursery with Corinthian and Attic ware[citation needed]. The distinctive Red Samian ware of the Early Roman Empire was copied by regional potters throughout the Empire. The Dark Age period saw a collapse in the quality of European pottery nursery which did not recover in status and quality until the European Renaissance[citation needed]. [edit] In archaeology pottery nursery found at Çatal Höyük – sixth millennium BC For archaeologists, anthropologists, and historians the study of pottery nursery can help to provide an insight into past cultures. pottery nursery is durable and fragments, at least, often survive long after artifacts made from less-durable materials have decayed past recognition. Combined with other evidence, the study of pottery nursery artifacts is helpful in the development of theories on the organisation, economic condition and the cultural development of the societies that produced or acquired pottery nursery. The study of pottery nursery may also allow inferences to be drawn about a culture’s daily life, religion, social relationships, attitudes towards neighbours, attitudes to their own world and even the way the culture understood the universe. Chronologies based on pottery nursery are often essential for dating non-literate cultures and are often of help in the dating of historic cultures as well. Trace element analysis, mostly by neutron activation, allows the sources of clay to be accurately identified and the thermoluminescence test can be used to provide an estimate of the date of last firing. Examining fired pottery nursery shards from prehistory, scientists learned that during high-temperature firing, iron materials in clay record the exact state of Earth’s magnetic field at that exact moment. [edit] Environmental issues in production Although many of the environmental effects of pottery nursery production have existed for millennia, some of these have been amplified with modern technology and scales of production. The principal factors for consideration fall into two categories: (a] effects on workers and (b) effects on the general environment. Within the effects on workers, chief impacts are indoor air quality, sound levels and possible over-illumination. Regarding the general environment, factors of interest are off-site water pollution, air pollution and disposal of hazardous materials. Historically plumbism, lead poisoning, was a significant health concern to those glazing pottery nursery. This was recognised at least as early as the nineteenth century, and the first legislation in the United Kingdom to limit pottery nursery workers’ exposure was introduced in 1899.[12] Whilst the risk of to those working in ceramics is now much reduced it can still not be ignored. With respect to indoor air quality, workers can be exposed to fine particulate matter, carbon monoxide and certain heavy metals. The greatest health risk is the potential to develop silicosis from the long-term exposure to crystalline silica. Proper ventilation can reduce the risks, and the first legislation in the United Kingdom to govern ventilation was introduced in 1899.[12]. Another, more recent study at Laney College, Oakland, California suggests that all these factors can be controlled in a well designed workshop environment.[13] The use of energy and pollutants in the production of ceramics is a growing concern. Electric firing is arguably more environmentally friendly than combustion firing, although the source of the electricity varies in environmental impact.[citation needed] [edit] Other usages Due to the large number of pottery nursery factories, or colloquially, ‘Pot Banks’, the English city of Stoke-on-Trent, one of the first industrial cities of the modern era where, as early as 1785, two hundred pottery nursery manufacturers employed 20,000 workers, is often called “The Potteries”.[14] For the same reason the largest football club in the city are known as “The Potters”.[15]