1. Ceramic Glazes
REVIEW

2. Ceramic Glaze
a mixture of powdered materials made into a formula that fuses onto a ceramic piece when heated through
Silica – the glass former; found naturally in sand
Flux – the temperature reducer; helps the glaze melt
Alumina – the stabilizer; keeps the glaze from running off of the ceramic piece; helps glaze stick

3. Finishes of Ceramic Glaze
Underglaze – can be applied to greenware or bisqueware; matte in finish; not food safe on own
Used in pottery to add intricate designs or patterns to the surface of the clay before being glazed
Underglaze pencils can be used to add small details

4. Finishes of Ceramic Glaze
Liquid Glaze – a type of glaze that produces a high shine/gloss, semi- matte, or matte finish on the surface of ceramics; mostly food safe
used over underglaze work to make it food safe
can be used on own
comes in all colors, from clear to black

5. Can you eat/drink off of your pottery?

6. How to Apply glazes appear differently with different applications
Opaque color = 2-3 layers
Semi-Transparent = 1 layer

7. How to Apply
Glaze can be applied by dipping, pouring, brushing or spraying onto the surface
Bottom of piece must be free of glaze
Will fuse to the kiln shelf
OR bottom can be glazed, but stilts will be used
To prevent from fusing to shelf

8. Can you mix Glaze?
Most glazes can be mixed together, just like you would paint
Mixing can produce different colors
Layering glazes can produce different effects

9. Glazing Problems
Crawling – empty spots left on a ceramic piece due to oil or dirt on the greenware/bisqueware piece
Can also be because of a thick application of glaze
A glaze formula that has too much or not enough of silica, flux, alumina
Some artists purposely do this, others, it happens on accident

10. Crazing
When the shrinkage rates of the clay and the glaze differ from one another
Tiny cracks appear in on the surface
After it is removed from kiln
After a couple of weeks

11. Running/Pooling
When glaze runs over and down your piece, sometimes pooling on the kiln shelf
Happens when too much glaze was applied

12. Blistering
Result of escaping gas when the glaze is firing too fast or the coat of glaze is too thick

13. Pinholes
Little holes that result from air holes in the clay

14. Rough Surface
A rough surface (not glossy) that results from applying a thin layer of glaze

15. Consistency
Glaze should look/feel like thick milk, cream or pancake batter
Not too thick, not too thin
Glaze needs to be shaken in the bottle and stirred
Sediment can settle to the bottom of the glaze bottle and needs incorporated
Water can be added to dry, chunky glaze
Let sit overnight and stir next day

16. Color
Due to chemical reactions that happen during the firing process, the color of glaze greatly changes within the kiln
Check test tiles hanging below the glaze
No test tiles? Go on the glaze brand’s website and check