- Insoluble opacifier
- Melts at 2102°F
- Traditionally used in low-fire majolica glazes called “tin whites.”
- Unlike typical stark, harsh, white characteristic of zirconium opacifiers, tin oxide adds white to the glaze that may range from soft, warm white to bluish milk-white
- Considered to be the best opacifier, is used in amounts from 1-15%
- Is twice as strong as zirconium opacifier
- In reduction atmosphere or at high temperatures loses its opacifying power
- May produce rough gray cloudy surface instead
- Combined with colorants, makes other colors like copper reds or chrome pinks
- Prone to flashing if volatile colorants are present in kiln
- Ex. may develop flashes of pink or red.
- High expansion and contraction, which can increase crazing
- Pinholes, matte surfaces, and crawling sometimes result due to high viscosity and surface tension
- Has no known toxicity