1. Ceramics Vocabulary

2. Notes on clay
3 materials make up a clay body: plastic material – any clay or combination of clays from the ground flux – feldspar, glass or bone ash filler – silica, sand, ground shards or grog.

3. Flux
A substance that lowers the melting point of another substance; changes the firing temperature of a given natural clay

4. Filler Subdues sticky quality of highly plastic natural clays
Feldspar powder

5. Grog
Crushed or ground particles of fired clay graded in various sizes of particles. Added to the clay body to help in drying and to add strength and texture.

6. Types of clay
Earthenware; low temp (below cone 2) and is porous, soft usually red - brown in color. It gets its color from iron in the ground.
Stoneware: type of clay fired to a temp at which the body becomes vitrified (non porous). Natural colors range from brown to white (we use white)
Porcelain: a translucent nonabsorbant body fired at a high temp. First developed in China

7. Methods of Handbuilding
Pinching: using hands to pinch a shape, good for organic forms. Simplest form of construction.

8. coiling
Rolling long sections of clay to build layer by layer. ALWAYS score between coils or your sections won’t stay together. You work from the bottom up when coiling.

9. slab
Rolling out clay into a flat piece (not less than ¼ inch or it will be unstable). Working with slabs is similar to building with wood. It is good for geometric shapes.

10. Modeling
Using a solid lump of clay to form an object. It must then be hollowed out to less than ½ thick.

11. Clay timeline:
Slip/slop/slurry: the suspension of raw ingredients in water. Mixed together this is clay its first state. Also used as a “glue” to join pieces of clay that are leatherhard. Can be pigmented for decorative work.

12. Leather hard: the condition of the clay body when much of the moisture has evaporated and shrinkage has begun. This is best time to join pieces together, carve into the surface or burnish surface.

13. Greenware: unfired pottery or sculpture ready for first fire
Greenware: unfired pottery or sculpture ready for first fire. Also called “bone dry”. Caution – clay is its most fragile at this point and will break very easily.

14. Bisqueware: unglazed ceramic ware that has been fired once at a low temperature to remove almost all moisture. Takes glaze best in this state.

15. Glazeware: clay that has been fired 2 or more times producing a hard permanent surface.

16. GLAZing
And kiln firing

17. GLAZE:
A glassy melted coating developed by chemicals and heat on clay.

18. Like clay, there are 3 major components:
1- the glass former- silica! This is the basic component of a glaze and is why it looks the way it does and why it is functional!
2- the flux- this lowers the melting temperature of the glaze mixture (remember the silica problem… it has a melting point of 3000 degrees F!)
3- the refractory- this increases the viscosity and stability of a glaze. What this means is that it controls how much or how little a glaze will run. Will it drip and move a lot, or a little.

19. Some tips to glazing success….
APPLY ONLY TO BISQUEWARE!
USE 2-3 COATS !
MAKE SURE YOU APPLY EVENLY!
NEVER NEVER NEVER NEVER EVER glaze the bottom of your piece!

21. OXIDATION At Assumption, we will ALWAYS do firing. :
The firing of a kiln or open fire with complete combustion so that the firing atmosphere contains enough oxygen to allow the metals in clays and glazes to produce their oxide colors

22. With oxidation firing, our glazes will tend to be uniform in color and will achieve more color than reduced wares.

23. REDUCTION
-Reduction firing is the opposite of oxidation firing. This is when oxygen is denied access into the kiln at some point in the process.
-Technically, carbon monoxide in the kiln combines with the oxygen in the oxide of the clay body and glazes, causing the oxides to change color
-this is usually a high fire glazing process

24. Our kilns have inside them a clever device known as a kiln sitter.
along with a thing called a cone, this device shuts the kiln off when it reaches the desired temperature (cone 06 for bisque, cone 6 for glaze).

25. CONES work like negative and positive numbers…
06 (1852 degrees F)
6 (2266 degrees F)
-They rage from cone 022 (1121 degrees F) to the hottest being around cone 15 (2610 degrees F).

26. And these things are what shuts off the kilns
And these things are what shuts off the kilns! Yes, these funny things are cones! These are each made to melt at specific temperature.

27. In the end, its MOST important that you remember TWO things:
1- remember that ceramics teaches us much about life and about letting go and about forsaking control.
2- PLEASE remember to wash your hands well before you leave here. NEVER EAT OR DRINK WHILE GLAZING!