|Molar Mass||150.71 g/mol|
|Melting Point||1630 Degree C|
Tin oxide is the most effective opacifier of all. One or two percent will opacify a glaze and improve its gloss. Normally about five percent of tin oxide added to a glaze will completely opacify it. For polishing purpose, tin oxide provide the marble or granite with much luster. The fully oxidized state of tin metal. It is a very white powder of low density. Although tin metal melts at a very low temperature, the oxide form is quite refractory.Tin oxide has been used primarily as an opacifier in amounts of 5-15% in all types of glazes for many centuries. The amount required varies according to the glaze composition and temperature. The mechanism of the opacity depends on the white tin particles being in suspension in the molten glass. At higher temperatures, these particles will start to dissolve and opacity will begin to be compromised.Like zirconium oxide, larger amounts of tin in lower temperature glazes have a refractory effect, stiffening the melt and increasing the incidence of pinholing and crawling.Tin oxide white is considered a softer white than that produced by the very popular and much cheaper zirconium opacifiers.One peril with tin oxide SnO2 is that it reacts very strongly with minute amounts of chrome to produce pink colors. If volatile chromium is flashing in the kiln atmosphere from other glazes, the white color will be lost.Other opacifiers include zirconium oxide (gives a harsher glassy white), calcium phosphate (problems with off-coloring to greys), cerium oxide (restricted to low temperatures), antimony (dissolves in some glazes and gives yellows with lead), and titanium dioxide (discolors if any iron oxide is present).Stannic oxide is derived from tin. Widely known and used, tin comprises about 0.001 percent of the earth's crust. It is sometimes found alone, but generally is found as the oxide in the mineral cassiterite. Tin mines exist in England, Spain, Indonesia, Thailand, Zaire, Nigeria and China. Significant amounts of tin is also obtained through recycling. Tin is nontoxic, ductile, malleable, adheres to various metals and has a relatively low melting point. These properties lend to its usefulness as a rust-proofing material on iron, low-grade steels, copper, and copper alloys.