Jim’s Mottled Brown Cone 6 Ramped Up to a Cone 10

Recipe:

Ball Clay                                2.5

Dolomite                             30.3

Spodumene                         30.3

Tin Oxide                             3.3

Zircopax                               4.2

Flint                                     29.4

Add 4% Iron Oxide

This glaze recipe was the result of revising the cone 6 recipe in the blog above to a cone 10 recipe fired in reduction. The UMF was employed to  guide the glaze limit formula and alumina to silica ratio. The first step was to remove the Gerstley Borate. The boron in the Gerstley complicates the UMF, has a low melting range, acts as a glass former, and is an additional flux. Flint was added to bring the Al:Si ratio up to 1:7. The resulting glaze is an opaque, glossy, caramel color. There is a variation in color, especially when breaking over texture, but not as strong a mottling effect as in the cone 6 recipe. There is crystal formation throughout the glaze. Good coverage from the glaze, with no pin holes. The glaze is of low viscosity and will tend to be runny.