This lesson we made line blends, the purpose of this line blend was to test the effect that glaze colourants play in the glaze mix. Line blends consist of ascending and descending ratios of 2 different ingredients, in this case, colouring oxides.
This test was done on JB3 stoneware clay, and the glaze recipe used was-
Bernard Leach base glaze – 40/30/20/10
potash feldspar 40
with the addition of manganese dioxide and rutile.
We mix up 2 x 100 grams batches of the base glaze, in 2 separate plastic cups, and add to the first cup add 5% manganese dioxide (Mn) colourant to the base glaze, and to the second cup add 10% rutile (Ru) to the base glaze. So we end up with 2 cups with 2 different colourant in each glaze.
The left hand side, tile 1, starts with the 100% manganese glaze recipe, and the right hand side, tile 11, with the 100% rutile glaze recipe, then you work from left to right, tile 2 equals 9 parts manganese recipe to 1 part rutile recipe, tile 3 equals 8 parts manganese recipe to 2 parts rutile recipe, and so on.
After firing to cone 9, one set in reduction, one set in oxidation, the results where pretty nice. I liked the Bernard leach base it has a low gloss sheen to it, smooth to touch, and I also liked the effect of rutile (titanium) suspended in the glaze. The colours varied from transparent brown, purple/blue, tan, beige in oxidation, to transparent green, tan, beige and slight opaque green in reduction. I lean towards liking the rutile end more.
by the way ignore my mistake of writing Mg instead of Mn on the reduction tiles. Mg stands for magnesium, Mn stands for manganese.