Kiln Wash Prevents Hot Glass
Sticking To Glass Kiln Shelves

Also known as shelf primer or glass separator kiln wash is a method used to prevent hot fusing glass sticking to a kiln shelf.

This is a cheaper method than using shelf paper but it will produce a slightly rough finish on the back of the fused glass piece.

It is also used as a coating for glass fusing slumping and drop molds.

For jewelry making it is used quite often on molds to produce frit based jewelry pieces as per photo of the coated jewelry mold on the right.

It comes in a powder form and is mixed with water as per the makers’ directions.

Caution is needed when handling the powder and a respirator should be worn to prevent inhaling any dust.

The wash usually has a colouring agent that will burn off during firing; this allows you to tell if the shelf has been fired.

Wash is normally applied to the shelf or mold with a special soft brush known as a Haike brush; these brushes come in various sizes.

It is usually applied in four or five coats making sure that each coat is applied in a different direction to the previous coat. Each coat should be allowed to dry before applying the next coat.

Once again follow the makers directions.

Stainless steel molds should have the surface roughened with abrasive paper so that the wash will stick to the mold.

The mold will need to be heated up to 350f/180c before applying the wash. Spraying the wash on the heated mold is one of the methods used. Wear heat proof gloves to remove the mold from the kiln.

Stainless steel and ceramic molds can also be coated with boron nitride spray.

Wash can be applied with a good quality brush to the warm mold, do not use a foam brush for this purpose. As the wash is applied the mold will cool down and the wash will no longer stick. The mold will need further heating to complete the coating process.

Any unused wash can be kept in a sealed container and used later.

Primed shelves can be used three or four times depending on firing temperatures.

Clean the old wash off before applying new coats.