Wax resists, wax emulsions, and actual melted wax itself are all used in pottery. The function of the wax resist is to keep liquids, such as raw liquid glazes, from adhering to the clay body of a pot. The most common use for wax resists is also the most practical.
Any speck of glaze material on the bottom of a pot can cause it to weld to the kiln shelf during firing. Even washing the bottom of a pot off after glazing is not enough to keep pots safe for this fate. Therefore, most potters apply wax resist to the bottoms of their pots before beginning the glazing process.
To Wax Your Pots' BottomsUse a brush or sponge that you don't care about if it gets ruined. Coat the bottom and up the sides of the pot one quarter of an inch. Allow the resist to dry thoroughly. If the coating seems thin, apply a second coat of wax resist. Allow the resist to dry completely before applying glazes to the pot. After glazing, wipe any beads of glaze material off the bottom and bottom edge of your pot. The wax resist will fire off the pot in the kiln.
Tip: Commercial wax resists and wax emulsions are much easier to use than melted wax. Many can be washed out of brushes or sponges with warm soap and water. Check product directions for further information on how to use specific products.
Tip: Avoid air bubbles in the wax resist. Air bubbles result in thin areas of resist and can lead to unwanted glaze adherence.