- Main glass-former in ceramics
- Sometimes comprises 50-75% total oxides in glaze
- Has melting point of 3110°F
- Usually non-toxic when combined in melt with other minerals
- As “free silica” dust it can cause silicosis, an untreateable lung disease
- Presence increases hardness, durability and acid resistance
- Has very little effect on color
- If too much is added it will create silica mattes, opaque, sugary surfaces that will affect color because much of the material in glaze remains unmelted
- Generally added to glazes in its 200-mesh form
- Available in other mesh sizes, too
- Has over 20 different structures, or crystal formations, which only three most directly pertain to ceramics
- Can exist as a crystal glass, or cristobalite
- All of these materials are chemically the same
- Only physical arrangement is different
- As crystal, it has a very ordered arrangement
- With high rate of expansion and contraction
- Cristobalite
- Crystalline state of silica
- Even higher expansion and contraction rate than crystal silica
- As glass, it has cooled so quickly it has amorphous arrangement
- Very low expansion and contraction rate
- Has medium surface tension and viscosity.
- Insoluble sources include silica (various mesh sizes), cristobalite, flint/chert (containing up to 5% CaO), Kaolin/clay, feldspar, wollastonite, talc, Frits, zirconium silicate, Macaloid, pyrophyllite, silicon carbide, kyanite, wood ash (some plant ash contains up to 70% silica), sand, and mica.