Touchtone Red Glaze, ^6 to 7, oxidation

I started using this glaze a few years ago (got it from Rebecca Varner in a Clayart mug exchange) and have loved it for the excitement it gave to opening the kiln. ..never quite sure what to expect. Where thinly applied it is often a deep navy color. There is often a varying amount of sort of an olive color and whoopee! look at all that red, lovely iron red. This vase, which I call "Red Dancer" has the kind of result I hope for from this glaze. It is of white stoneware.

When I ran out of this glaze a while ago, I mixed up a new
batch, and was very disappointed; there was a lot of the olive, but not a nice olive, some sort-of black, and some brownish red, or faintly reddish brown. I didn't even take any pictures- all the pieces were designated to be re-dipped and refired. I remembered that I had used some red iron oxide from a different source, and thought that might be the problem. I also checked my firing logs to make sure I didn't go hotter or cool down faster. That was all about the same.

So, last week I mixed a new batch (half recipe, actually) and fired over the weekend. The result: better, but different, sort of spotty- maybe I need to strain it a few more times.

You can see my liner glaze was fluid enough on the rim to carry down the stripe I did just under the rim. The stripe was half RIO, half rutile. Anyway there is some decent red here, as well as pale olive. I actually don't mind the blotchy look, at least on this piece. I took a macro of the area where the glaze is thinner- you can really see the color change. This bowl is a buff stoneware, by the way.

I swear there is no cobalt in this glaze. I rolled the bowl around in the glaze pan and didn't quite go all the way, so here's the area of thinner glaze.

The recipe is in the Clayart archives, I'm sure, but here it is anyway:

TOUCHTONE RED, cone 6/7, oxidation
15 minute soak, slowed cooling

Gerstley Borate 31
Flint 30
Feldspar 20 (I used Kingman)
Talc 14
EPK 5

Add Red Iron Oxide 15