Glaze test results

Yesterday's class was looking at 5 sets of glaze tests. And talking about them to learn what we were looking at. I learned a lot, not just about glazes too. Marty, Cathy, Wendy, Erin, and I listened to Annie Singletary's experiences with glazes.

But on a personal note, my glaze tests were fired in 2 kilns...at different temperatures. So that was the first basic difference that was noted. The glaze which was supposed to be a satin matt looked great as a matt at cone 06, as fired in the studio. And the cone 04 kiln had a different cooling and heating cycle, using some kind of Enviro-Vent, whatever that is. But that set of glaze tiles (same exact batch of glaze) came out with high sheen. The recipe was designed for 04, I'm pretty sure, by Val Cushing.

And did I get a grey? Nope. Lots of turquoise and green and blues. So Annie said she'd send me a Mason Stain number for grey...which is a source of premixed colors that are to be added to a glaze. But since I don't mix my own, I probably won't be able to use it...unless I add it to some of the glazes the studio has. That might work...if they'll let me. Maybe I'll test that sometime.

The grey was intended for use on my tree sculptures. So I will eventually have something that replicates tree bark. Isn't it funny that earth chemicals don't make grey glaze? Especially since dirt is usually that color. Not to mention every tree out there. Where do they get the chemicals that combine into that nice soft grey? Somehow not from any of the ones available to pottery studio glazes.

But wait, the paints and manufactured glazes have black, white, and shades of grey in between. So it isn't that there isn't a source of "greyness" pigments. It's just that it isn't available in the pallette of chemicals that are mixed for studio glazes. They can't do red either. Glass often has nice reds, but the only red that pottery can have, besides the rust colors from iron, is the copper red that's achieved in a reduction kiln. Reduction means the oxygen is reduced in the firing which allows copper to turn a bright ruby red...rather than the shades of green it usually has.

I thought of glass because it also goes into a kiln and is melted. But it's not the same as the glass of a glaze on a pot. I don't know why though.

I found black copper carbonate at 2% added to a base glaze forms a nice pale turquoise, so I may try that, if I ever want it. I also learned (thanks to Erin) that plumbers cement is a great glue for clay. I've been stuck with super glue all these years (pardon the pun)...but she says she can use it for lots of different places, and then paint on top of it so it doesn't show. That's great.

I'm happy that there are manufactured glazes that mostly will be the true colors they are designed for. I'm also happy there are potters like Annie who develop new chemical formulas for glazes that aren't manufactured, and test them and then use them on their wares. Annie's pottery is sensuous and lyrical...always a joy to see and handle. Bu we go in entirely different directions. I hope sometimes my sculptures are also sensuous and lyrical. Perhaps.