Slip (ceramics)
Encyclopedia
A slip is a suspension in water of clay and/or other materials used in the production of ceramic
ware. Deflocculant, such as sodium silicate
, can be added to the slip to disperse the raw material particles. This allows a higher solids content to be used, or allows a fluid slip to be produced with the a minimum of water so that drying shrinkage is minimised, which is important during slipcasting
. Usually the mixing of slip is undertaken in a blunger
although it can be done using other types of mixers or even by hand.
An engobe is a material similar to a slip, with somewhat lower clay content, higher proportion of flux
, and added filler, and in some cases a colorant.
Ceramic
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
ware. Deflocculant, such as sodium silicate
Sodium silicate
Sodium silicate is the common name for a compound sodium metasilicate, Na2SiO3, also known as water glass or liquid glass. It is available in aqueous solution and in solid form and is used in cements, passive fire protection, refractories, textile and lumber processing, and automobiles...
, can be added to the slip to disperse the raw material particles. This allows a higher solids content to be used, or allows a fluid slip to be produced with the a minimum of water so that drying shrinkage is minimised, which is important during slipcasting
Slipcasting
Slipcasting is a technique for the mass-production of pottery, especially for shapes not easily made on a wheel. A liquid clay body slip is poured into plaster moulds and allowed to form a layer, the cast, on the inside cavity of the mould...
. Usually the mixing of slip is undertaken in a blunger
Blunger
A blunger is a machine commonly used in the pottery industry for mixing clay and water. A blunger usually consists of a round or octagonal tank with a mixer. Clay is added to the water filled blunger and then mixed into a slurry, which is also called slip...
although it can be done using other types of mixers or even by hand.
An engobe is a material similar to a slip, with somewhat lower clay content, higher proportion of flux
Ceramic flux
A ceramic flux functions by promoting glass formation in clay bodies and glazes. Fluxes are used in glazes to lower the high melting point of silica. The most commonly used fluxes in a ceramic glaze are lead, boric, soda, potassium, lithium, calcium, magnesium, barium, zinc, and strontium...
, and added filler, and in some cases a colorant.
Use
A slip may be made for various purposes in the production and decoration of ceramics. Slip can be used:- As a means of mixing the constituents of a clay body.
- To shape ware by slip castingCeramic forming techniquesCeramic forming techniques are ways of forming ceramic shapes. This can be used to make everyday tableware from teapots, to engineering ceramics such as computer parts. Methods for forming powders of ceramic raw materials into complex shapes are desirable in many areas of technology...
. - To join of sections of unfired ware, such as handles and spouts.
- To adhere figures or other motiffs to unfired ware to form a bas-relief. This technique is known as sprigging, an example is JasperwareJasperwareJasperware, or jasper ware, is a type of stoneware first developed by Josiah Wedgwood, although some authorities have described it as a type of porcelain...
. - Decoratively when placed onto a wet or leather-hard clay body surface by dipping, painting or splashing. Such type of ware is often described as slipwareSlipwareSlipware is a type of pottery identified by its primary decorating process where slip was placed onto the leather-hard clay body surface by dipping, painting or splashing...
. Slipware may be carved or burnished to change the surface appearance of the ware. Specialized slip recipes may be applied to biscuit wareBisque (pottery)Bisque porcelain is unglazed, white ceramic ware Examples include bisque dolls.Bisque also refers to "pottery that has been fired but not yet glazed...
and then refired. Decorative slips may be a different color than the underlying clay body or offer other decorative qualities. Colored slips can be used to create pieces of ceramic artCeramic artIn art history, ceramics and ceramic art mean art objects such as figures, tiles, and tableware made from clay and other raw materials by the process of pottery. Some ceramic products are regarded as fine art, while others are regarded as decorative, industrial or applied art objects, or as...
by techniques similar to paint in other media.