4-7% will produce a semi-opaque glaze, white (with a blue hint) at 5-9%, 8-10% will give a full opaque. Useful as a white decorative pigment / underglaze - either alone or mixed with a small amount of a transparent glaze. Copper red glazes need tin, chrome and tin produce pinks if no zinc or boron is present. If any chrome glazes are fired in the kiln it can turn a tin white glaze pink. Tin and iron can create variegated surfaces. Glass jar is for illustration purposes only.