Ceramic Glazes REVIEW

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

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

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

Can you eat/drink off of your pottery?

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

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

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

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

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

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

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

Pinholes Little holes that result from air holes in the clay

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

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

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