The remains of the glaze
Nov. 6th, 2020 03:57 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
offcntrMore pots from the latest glazing cycle, loading into the kiln Sunday. It's been a busy week at Club Mud, everybody jockeying for space as we prepare for the holiday season. I'd a bunch of dinner plate orders, from three different customers; here's a representative sample.
I once again took on a new pattern: a Northern Saw-Whet Owl, aka the second cutest damn thing in feathers. (I'm sorry, a potoo will always be first.) She wants a tall mug. Being me, I did three, plus a dessert plate, and wound up painting one on a glaze test as well.
The glaze test was because we'd gotten a donation of raw materials from a closing studio. This happens fairly frequently, and our supplies person usually just dumps them into the appropriate bin or bucket. This time, though, she was a little suspicious.
The bag in question was marked "Talc," fifty pounds of fine white powder. The problem is, the talc we usually source from Georgies is a dark grey. It could be fine, different deposit, same composition; but once, it... wasn't.
We'd gotten a bag of white talc from another donor, dumped it in the bin, and I mixed up a 7000-gram batch of my base white glaze. Used it on half of the pots in my next firing, all of which came out brown and matte, rather than cream/white gloss.
As far as we could tell, the material was whiting--calcium carbonate--rather than talc--a magnesium silicate. I had to trash a bunch of pots, was about to throw away the glaze, but Jon though he could use it, so I gave it to him. But you can see why I'm leery of off-color talc.
So I mixed up a 100-gram batch to test. The only thing I had to try it on was a bisqued wall-art tile, and it seemed a shame to leave it undecorated.
I once again took on a new pattern: a Northern Saw-Whet Owl, aka the second cutest damn thing in feathers. (I'm sorry, a potoo will always be first.) She wants a tall mug. Being me, I did three, plus a dessert plate, and wound up painting one on a glaze test as well.
The glaze test was because we'd gotten a donation of raw materials from a closing studio. This happens fairly frequently, and our supplies person usually just dumps them into the appropriate bin or bucket. This time, though, she was a little suspicious.
The bag in question was marked "Talc," fifty pounds of fine white powder. The problem is, the talc we usually source from Georgies is a dark grey. It could be fine, different deposit, same composition; but once, it... wasn't.
We'd gotten a bag of white talc from another donor, dumped it in the bin, and I mixed up a 7000-gram batch of my base white glaze. Used it on half of the pots in my next firing, all of which came out brown and matte, rather than cream/white gloss.
As far as we could tell, the material was whiting--calcium carbonate--rather than talc--a magnesium silicate. I had to trash a bunch of pots, was about to throw away the glaze, but Jon though he could use it, so I gave it to him. But you can see why I'm leery of off-color talc.
So I mixed up a 100-gram batch to test. The only thing I had to try it on was a bisqued wall-art tile, and it seemed a shame to leave it undecorated.
no subject
Date: 2020-11-07 01:15 am (UTC)no subject
Date: 2020-11-07 06:01 am (UTC)