Pottery - Wikipedia
In visual art, there is no difference between ceramics and pottery. Both denote the basic. What are pottery and ceramics? Is there a difference? Is everything made out of clay pottery? Here are the answers. Pottery vs. Ceramics. When one says pottery or ceramics, people tend to relate them easily with clays. For thousands of years these two have.
These are weak but still significant forces. They are weak enough to allow the clay sheets to slide past each other when some force is applied, but strong enough to keep them in position once the force is removed. In other words, clay can be moulded into a shape, which it then keeps. The kaolinite hydroxyls become hydrogen bonded to the next layer, forming a stronger, firmer structure 'green ware'.
If at this point the clay object is put into water it will disintegrate and can be returned into a workable state. A typical example is orthoclase, whose approximate composition is given as K2O. Over the geological timescale a great deal of feldspar has been eroded through a weathering process, mainly through the action of water. Although these rocks seem solid and eternal, over millions of years the effect of rain, made slightly acidic by dissolved CO2, does dissolve some of the alkali and alkaline earth metal oxides leaving the silicon and aluminium oxides: When transported by water the particles continue to be ground finer and finer by the action of other rocks.
They are also separated by size according to what settles out first. As a result, clay is a major component of soil all over the world, with a variety of properties according to the precise conditions that applied during its formation.
On the aluminium oxide surface of the 'sheets' some of the oxygens are in the form of OH groups and there are OH groups within the structure as well. Broadly speaking, there are two main categories of clay minerals: Part structure of kaolinite: Si - buff, Al - grey, O - red, H - white. Click the image for an interactive version Source: The crystal structure shows plate-like particles, which are stacked in layers linked by hydrogen bonds.
It is through the structure, properties and transformations of kaolinite that we can understand the physical changes involved in the making of a pot.
Difference between Pottery and Ceramics
Although there are deposits of virtually pure kaolinite, in practice it is always used as part of a mixture with other minerals, either because it is dug out of the ground in an impure state and used directly or because it is blended with other minerals eg feldspar and quartz to achieve the desired properties. At this point the clay is very fragile and crumbly, but it can no longer be reconstituted into the original workable state.
This stage is described as the driving off of the so-called chemically bound water: When this happens the clay can no longer be recycled. At the same time the regular sheet-like crystal structure of kaolinite is being lost and amorphous metakaolinite is formed. Biscuit ware is quite strong and porous; it readily absorbs water and dries again very easily. It is glazed by spreading a suspension of the glaze solids in water over the pot by pouring, dipping or spraying, and when it is dry, firing it again at the appropriate temperature for the clay and the glaze.
In every case the clay composition has to be so that at the 'maturing temperature' it begins to vitrify and the partial melting of some of its components provides the 'glue' to provide its strength. Other chemical changes take place during firing. These include burning off all organic matter often found in many clays, the decomposition of carbonates, which are common ingredients of many glazes, and further crosslinking of metakaolinite to give a three-dimensional network with the elimination of water.
Gilding An advanced decorative technique utilizes metallic mixtures of eg powdered gold, silver, copper or platinum to achieve a range of colours and effects. When applied to a fired body, gold produces a purplish hue, silver a straw colour, copper anything from lemon yellow to gold or brown, and platinum a silver tone.
Printing This decorative method includes the use of transfer printing, as well as modern lithographic methods. Ives, Cornwall, where he built a traditional Japanese wood burning kiln. Leech viewed pottery as a combination of art, philosophy and design although he was also a strong advocate of utilitarian rather than fine art work. Inthe Victoria and Albert Museum in London staged a major exhibition of his art, and his work is represented in several museum collections including the Tate St Ives.
After three years in St Ives he returned to Japan where he founded a world-famous pottery studio in the town of Mashiko. She continues to design a range of glass and ceramic items. A member of the erstwhile 'contemporary ceramics movement', his work appears in many museums including the Smithsonian American Art Museum and the Honolulu Academy of Arts.
He is the recipient of numerous awards including an honourary doctorate from the Royal College of Art in London. Sackler Gallery and the Smithsonian Institute. Other famous ceramic artists include: Small amounts can be added to porcelain to increase plasticity. Fire clay A clay having a slightly lower percentage of fluxes than kaolin, but usually quite plastic.
It is highly heat resistant form of clay which can be combined with other clays to increase the firing temperature and may be used as an ingredient to make stoneware type bodies.
Stoneware clay Suitable for creating stoneware. This clay has many of the characteristics between fire clay and ball clay, having finer grain, like ball clay but is more heat resistant like fire clays. Common red clay and Shale clay have vegetable and ferric oxide impurities which make them useful for bricks, but are generally unsatisfactory for pottery except under special conditions of a particular deposit.
Methods of shaping[ edit ] A potter shapes a piece of pottery on an electric-powered potter's wheel Pottery can be shaped by a range of methods that include: This is the earliest forming method.
Wares can be constructed by hand from coils of claycombining flat slabs of clay, or pinching solid balls of clay or some combination of these. Parts of hand-built vessels are often joined together with the aid of slipan aqueous suspension of clay body and water.
Prior to some shaping processes, clay must be prepared such as tablewares although some studio potters find hand-building more conducive to create one-of-a-kind works of art. Classic potter's kick wheel in ErfurtGermany The potter's wheel.
In a process called "throwing" coming from the Old English word thrawan which means to twist or turn,  a ball of clay is placed in the centre of a turntable, called the wheel-head, which the potter rotates with a stick, with foot power or with a variable-speed electric motor.
During the process of throwing, the wheel rotates 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 centring the clay—a most important skill to master before the next steps: Considerable skill and experience are required to throw pots of an acceptable standard and, while the ware may have high artistic merit, the reproducibility of the method is poor.
These can then be altered by impressingbulgingcarvingflutingand incising. Thrown pieces can be further modified by the attachment of handles, lids, feet and spouts. As the name suggests, this is the operation of shaping pottery 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 5 and 6 per cent. Granulate pressing, also known as dust pressing, is widely used in the manufacture of ceramic tiles and, increasingly, of plates.
Difference between Pottery and Ceramics | Pottery vs Ceramics
This is a shape-forming process adapted for the tableware industry from the method long established for the forming of thermoplastic and some metal components. 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 while 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 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 labour. Two moulds for terracotta, with modern casts, from ancient Athens, 5—4th centuries BC 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 labour, in one operation at a rate of about twelve pieces per minute, though this varies with the size of the articles being produced.
Developed in the UK just after World War II by the company Service Engineers, roller-heads were quickly adopted by manufacturers around the world; they remain the dominant method for producing flatware.
Specially developed polymeric materials allow a mould to be subject to application external pressures of up to 4. The high pressure leads to much faster casting rates and, hence, faster production cycles.
Furthermore, the application of high pressure air through the polymeric moulds upon demoulding the cast means a new casting cycle can be started immediately in the same mould, unlike plaster moulds which require lengthy drying times.
The polymeric materials have much greater durability than plaster and, therefore, it is possible to achieve shaped products with better dimensional tolerances and much longer mould life.
Pressure casting was developed in the s for the production of sanitaryware although, more recently, it has been applied to tableware. This is used to shape ware by pressing a bat of prepared clay body into a required shape between two porous moulding plates. After pressing, compressed air is blown through the porous mould plates to release the shaped wares. This is suited to the making of shapes that cannot be formed by other methods.
A liquid slipmade by mixing clay body with water, is poured into a highly absorbent plaster mould. 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 mould, which is then split open and the moulded object removed. Slipcasting is widely used in the production of sanitary wares and is also used for making much modern porcelain, especially figures.