- Primary stabilizer/refractory.
- Melts at 3722°F
- Helps stabilize glaze melt
- Helps keep on vertical surfaces of pot.
- Increases stiffness and viscosity of glaze
- Gives more durability and hardness, and controls melting-point of glaze
- Presence in glaze inhibits color response and produces dull colors and matte surfaces
- Inhibits crystal growth in microcrystalline glazes
- Has high viscosity and highest surface tension of all oxides, resulting in stiff glaze melts with chance of crawling
- Has low expansion and contraction rates
- Low toxicity.
- Insoluble in water
- usually introduced into glaze recipe by means of clay that contains both alumina and silica, which helps keep other ingredients suspended in glaze bucket
- Sourcing from clay also gives strength to dry, unfired glaze coating and keeps from dusting off pot.
- Insoluble sources include: alumina hydrate, alumina oxide, clays, kaolins, ball clay, feldspars, kyanite, Frits, amblygonite, mica, and Macaloid
