|Crystal glazes are an exciting array of colored glazes that “explode” with jewels of color during the firing process. They consist of a base glaze with pebbles, granules, and specks of contrasting glazes. During the firing, the crystals spread out to produce a burst of color. The base glaze may be gloss or matte; the crystals may be the same type of glaze or a contrasting type. In any case, the mixture is designed to melt and smooth out in the firing. Crystal Glazes are a lead-bearing glaze and should not be confused with the non-toxic crystal glazes called Crystalites.
Most crystal glazes require three coats. Crystal glazes that have a red glaze base should have four coats. Regardless of the base glaze, if enough of the glaze is not applied, the crystals will not melt into the surface. It is easier to get a good coverage of the base glaze if all but the last coat is applied without the crystals or with fewer crystals. Usually the crystals are in the bottom of the jar, so it is easy to put the base glaze into a container.
Apply the first two coats in the usual manner with a soft fan brush. Mix the crystals into the remainder of the glaze and apply the last coat with crystals; a fan brush is helpful when applying the last coat for even disbursement of the crystals. While glazing, continually stir down to the bottom of the jar to pick up the crystals that may have settled.
Larger crystals should not be placed where they can spread out toward the bottom of a piece. Large crystals in the bottom of a bowl cannot spread out as easily as they would on the outside of the bowl. Avoid too many crystals near the bottom of the piece. The application of too many crystals on a piece can cause it to split. A piece is unattractive with too few or too many crystals.
Apply to properly fired shelf cone 04 bisque
Use a soft fan brush to apply the first two (or three) base coats and to apply the final coat to disperse the crystals evenly.
Avoid a larger concentration of crystal towards the bottom of the ware.
Do not use on the inside of food containers.
Fire to shelf cone 06. If more flow is desired, fire to cone 05.