|Monthly Tech-Tip |
To make high SG brushing versions of these glazes I started by blender mixing 500 grams of the G2926B Whiteware base clear to 250g of water and 100g of Laguna gum solution. That yielded about 550 ml, the resulting 1.58 specific gravity makes each layer go on quite thick. For the black, we added 30g more of Mason 6666 stain (6%) and for white 50g of Zircopax (10%). This increased the specific gravity to 1.63, much higher than any commercial brushing glaze. The black recipe costs about 1.37 cents/ml for us to make (compared to Amaco C-1 Obsidian @ 3.92 cents/ml to buy). The price advantage would be much better if we were to add enough water and Veegum gelling agent to bring the specific gravity down to the 1.4 value of C-1.
At the leather hard stage the sides of these two L4410P low temperature dolomite body pieces were coated with AMACO velvet underglazes. Both were bisque fired and finished with a layer with the same transparent glaze. But the difference is the thickness of that glaze and the method of application: The one on the left got three thin layers of a brushing glaze. The one on the right was quickly dipped in a base coat version of that same glaze. Evidently there is a thickness threshold, which, when exceeded results in clouding.
G2926B - Cone 6 Whiteware/Porcelain transparent glaze
A base transparent glaze recipe created by Tony Hansen for Plainsman Clays, it fires high gloss and ultra clear with low melt mobility.
Hobbyists and increasing numbers of potters use commercial paint-on glazes. It's convenient, there are lots of visual effects. There are also issues compared to dipping glazes. You can also make your own.