Ceramics Final

States of Clay and Ceramic:

Slip-  Clay mixed water.   Can be different consistencies depending on water content.

Decorative Slip-  Very smooth watery slip, dyed with mason stains to be various colors.  Can be painted directly onto the surface of leatherhard clay or used in conjunction with other surface treatments .

Building Slip-  The clay we work with mixed with water.  Used in conjunction with scoring to build clay projects.  

Wet – Sometimes referred to as plastic.   In its natural state or straight from the bag.  A light touch will create a fingerprint.

Leatherhard- Clay at this state resembles leather or a hard cheese. Clay that is dry enough to handle and carve without distortion, but still damp enough to be joined and blended.  Hard to bend but soft enough to be carved.

Greenware- Unfired, bone dry pottery.  A state in which clay forms are the most fragile.

Bisqueware- Unglazed clay that has gone through the first firing process, undergoing a chemical change to become ceramic.  

Glazeware- A ceramic piece that has had glaze applied and has gone through the firing process a second time to create a glass coating on the surface.  The glaze firing is at a temperature lower than bisque.

Surface Treatments

Underglaze – A colored decoration applied to the bone dry or bisqued clay. This material is like a “paint” for clay in that (unlike glaze) it will stay where you paint it. You must cover with clear glaze.

Glaze – a material containing silica (glass) that is applied after clay has been bisqued. Glaze makes functional pottery safe to eat out of. It is available in a variety of colors as well as clear.

Decorative Slip – Very smooth watery slip, dyed with mason stains to be various colors.  Can be painted directly onto the surface of leatherhard clay or used in conjunction with other surface treatments .

Incising – Carving a design or pattern into leather hard clay. 

Sgraffito – Applying colored slip to leather hard clay, then carving a design or decoration through it (so that the original clay body is exposed).

Mishima- The Japanese pottery technique of filling the incised area with colored slip. After slip has hardened the surface is scraped leaving the slip incorporated within the clay.  

Texture-  Using tools or objects to disturb the surface of clay to create an interesting or pleasing effect.

Building Skills: 

Wedging- This is the method of “kneading” clay in order to remove air bubbles and make the clay more workable. 

There are two main varieties of wedging, spiral wedging and rams head wedging. 

Either method is acceptable. 

Joining - Joining clay is a critically important skill. Most of the broken ceramic pieces that we see

in class result from poor joining technique. Joining consists of two things:

Scoring – scratching up the surface of the two pieces of clay with a scoring tool 

or pin tool.

Slip – a mixture of clay and water, applied to the scored clay to act as a kind of

“glue” in joining the two pieces together. 

After scoring and applying slip, always smooth over the seams with your finger

to ensure that the joint is solid and free from cracks.

Methods of Construction: 

Pinch – Perhaps the most basic method, it involves pinching the clay between the fingers or other parts of the hand to form a ceramic piece. 

Coil – This method involves rolling out thin coils of clay which are then stacked (using score and slip) to create a ceramic form. This simple method can create amazingly intricate forms as well as huge vessels the size of a small car.

Slab – Using a slab roller or rolling pin, one creates a slab of clay. This slab can then be cut and joined (using scoring and slip) into a wide variety of forms. This method can also be used to create draped pieces (formed over drape molds). 

Wheel – Though initially challenging to learn, this method is an efficient way to create symmetrical, usually functional pieces such as bowls, cups and vases. This method consists of two parts, throwing and trimming. Throwing involves applying a series of techniques to plastic clay to center and shape your pot. Trimming is done when the thrown piece is leather-hard. Trimming completes the form of the piece and removes excess clay.