How do I stop my glaze from settling out ("hard-panning")?

Fritted glazes are particularly prone to hard-panning.

Bentonite clay (sku3411) is a suspending agent which slows down the settling-out of glaze particles. Add between 1 and 3 percent bentonite to the glaze powder and stir in, prior to adding water and sieving.

Adding a small amount of flocculant such as Calcium Chloride sku3415 or Magnesium Sulphate (Epsom Salts) sku3442 will cause the glaze particles to settle in a more loosely packed arrangement which are then more easily reconstituted.

To prepare a saturated salt solution, add the salt crystals to hot water and stir until no more can be dissolved. Allow the solution to cool completely. With a pipette, add a few drops of solution per litre of glaze slop (approx. between 0.1% and 0.5%) followed by thorough stirring. Continue small additions/ stirring until you see gelling (flocculation) occur. Larger additions of flocculant will cause the glaze to thicken, which is helpful if the bisque to be glazed is more vitreous.

Epsom Salts work by flocculating the clay content of a glaze. The lower the clay content of a glaze, the less effective the flocculant, which is why adding 1 to 3 percent bentonite before prepareing the glaze can help. In glazes which are self-deflocculating - ones containing high alkali frit, large amounts of soda feldspar or nepheline syenite - much larger additions of Epsom salts are required to overcome the self-deflocculation.