Thus any discussion about the use of tin oxide as an opacifier ends up comparing it with zircon products: Twice as much zircon is required to produce the same level of opacity. Like zircon, tin melts at very high temperatures and thus does not go into solution in typical glaze melts. Zircon will stiffen the glaze melt more than tin. Zircon is likely produce a harder glaze surface. Zircon will reduce the thermal expansion of the glaze more than tin. The quality of the white colour is different (tin tends to be more of a blue white, zircon a yellowish white). Tin is very expensive, this is likely to be the main reason for its much more limited use as an opacifier today. Zircon tends to have less of an effect on the development of metal oxide colors (e.g. tin reacts with chrome to make pink). Tin can react with titanium and rutile to variegate the glaze.11 glaze for cone 6.