Ingredients

Ingredient Amount
Gerstley Borate 16.00
Whiting 17.00
EPK Kaolin 35.00
Silica 32.00
Add Amount
Cobalt Oxide 1.00
Copper Carbonate 3.00
Rutile 6.00

Instructions


Detail of two mugs glazed with Slate Blue. The mug on the right was fired in a loosely packed kiln in my garage during winter and allowed to cool naturally. The one on the left was fired with the cone 6 slow-cool schedule here. Crystallization of the titanium from the rutile in the glaze shows an interesting variegation and made the surface semi-matte.

Fast cooled, this glaze is a simple transparent dark blue-green. Cooled slower, it makes for a nice layering glaze. Does not run. The crystallizing oxide is titanium, sourced from rutile.

This recipe was shared by Ian Hall-Hough in the May 2020 issue of Ceramics Monthly.