Ceramics Fundamentals- Vocab

Purdue Fort Wayne- Ceramics Fundamentals (Fall 2026)

Clay

A hydrous, decomposed rock or mineral that is workable and moldable. It is a
heavy, damp, plastic material that ‘sets’ upon drying and can be changed by heat into a hard, waterproof material.

Clay Body

A combination of clays mixed with ground rocks or minerals to control
characteristics like color, maturing temperature, density, strength, and glaze fit.

Earthenware

A porous clay body that matures at a low temperature. Because it remains
porous after it is fired, unglazed areas will absorb moisture. (Apply slips and glazes to
earthenware that are labeled “low-fire” or Cone 04. Here at PFW, the earthenware is
red/brown in color.)

Stoneware

A clay body that becomes dense, strong and vitrified (will no longer absorb
water) when fired above 2192°F. (Apply slips and glazes to stoneware that are labeled “high-fire” or Cone 10. Here at PFW the stoneware is gray in color.)

Leather Hard

Clay that has dried enough to be handled without becoming distorted, but
contains sufficient moisture to permit joints to be made and slips applied without cracking.

Bone Dry

The state of clay when it feels and appears completely dry (True bone dry clay
has had the chemical water driven off it during the bisque firing). The clay will have
become a lighter color and is in the most fragile state, so handle with care.

Greenware

Unfired clay in the leather hard or bone dry state. Usually refers to a clay
project that is finished and ready for the bisque firing. (Make sure you put your pieces on
the greenware shelf labeled for your class.)

Bisque Firing

The process of firing green ware at a low temperature to produce bisque ware.

Bisque ware

Unglazed ceramic ware that has been fired at a low temperature to remove all moisture from the clay body and to make handling easier during glazing. (After your pieces have been bisque fired they will be placed on the bisque ware shelf labeled for your class.)

Glaze ware

Bisque ware that has been glazed and ready for the glaze firing. (After your pieces have been glazed put them in the kiln room on the low-fire cone 04 glaze ware shelves if it is earthenware or outside on the table or shelves labeled high-fire cone 10 glaze ware if it is stoneware.)

Slip

A liquid form of clay for brushing or dipping on leather hard clay. (Be sure to use low-fire/cone 04 slip for Earthenware, and high-fire/cone 10 slip for Stoneware.)

Terra Sigillata

A very fine slip that can be used to coat pottery or sculpture. The fine particles in the thin slip make it easy to burnish or polish the surface it is applied to.

Glaze

A vitreous coating that has been melted onto a clay surface by the use of heat.
Made of fine-ground minerals that, when fired to a certain temperature, fuse into a glassy
coating. Glazes may be matte or glossy, depending on the components.

Sgrafitto

Decoration of pottery made by scratching through a layer of colored slip or terra sigillata to the differently colored clay body underneath.

Scoring

Scratching or roughing up the edges of damp or leather-hard clay before joining them to another piece of clay.

Coiling

A method of forming pottery or sculpture from coils of clay blended together to form walls.

Wedging

The method of kneading a mass of clay to get rid of air bubbles, lumps, and preparing a homogeneous material.

Slab Building

Constructing a piece of pottery or sculpture using soft malleable slabs or leather hard slabs that are hard (stiff).

Throwing

The term for forming pots on the potter’s wheel out of clay.

Trimming

In ceramics this refers to trimming excess clay off the foot or off the body of the pot to refine the form.

Volume

The amount of 3-dimensional space an object occupies.

Form

A three-dimensional geometrical figure (i.e.: sphere, cube, cylinder, cone, etc.),