Step 4: Glazing. Pottery glazes are a mixture of finely ground minerals often including silica (white beach sand), clay, lime, feldspar and many other materials.  These materials are mixed with water and applied to the pottery.  When fired the minerals fuse into liquid glass that covers the pot.  The bottoms of the pot must not be covered with glaze or they would be fused to the shelf during the firing process. Glaze is poured in the cup...   then poured out as the cup is rotated to give the inside of the cup an even coating of glaze. Another way to apply glaze is to dip the entire piece in glaze.  The piece is held with tongs. I formulate and carefully mix all my glazes. Glazing... Decoration can be applied to the bisque fire pottery before being covered with a clear glaze.