Well, the test tiles are out of the kiln. I wanted to make sure that the firing was just like any other, so i changed nothing. The only difference being that I left the kiln a bit longer before opening it. To pack out the kiln, I filled it with some beakers and a bowl using the glaze with the china clay in it.
One would hope that, under these conditions, the fault we're trying to fix would occur on the packing pots. But it hasn't. In fact, no sign of any peeling on any of the pots.
Anyway, here are the test tiles. A few nice ones, and a few duffers. The main duffer was 70% LBS, 30% hyplas, which was opaque. A good start.
I put some cones in the kiln. I had modified the firing slightly, a few weeks ago, and it is clear that I am now only getting cone 03, with cone 02 half down. Well, that's ok.
My favourite of the tests was the one I was most trying to avoid - the standard honey glaze, 75% LBS 25% body clay. The second tile has the black slip on it. It isn't black with the glaze on it - it's a dark brown - but the slip is black where the glaze isn't on it. Which is good, because I was going to draw through the glaze, a la Cardew.
The next two - 5 (80% LBS 20% AT) and 6 (90% LBS 10% AT) are pretty good. I prefer number 6, but not sure that 90% LBS is a good idea.
The next two are honey glazes of a sort, but quite light. One is 80% LBS 10% red clay 10% nepheline, and the other is 60% LBS 10% borax frit 15% red clay 15% hyplas. They're both quite nice but they're a bit streaky.
Here's the packing pots. Not that nice.
Look at this beaker - this is the china clay recipe. It's gone cloudy. Quite surprised by that and not entirely sure why. Well, it doesn't matter anyway, because it's getting thrown away, when I can work out where I'm going to throw it.
Well, not sure I've really solved anything, but I am going to mix some of (1) and either (5) or (6).
I've been looking at Dorothy Kemp's odd slipware book. She doesn't mention shelling at all, and says that the glaze pings off if you open the kiln too early. She also suggests a recipe for borax frit, which is just a mix of the frit and body clay. I might try that, just to see what it's like. I have some test tiles left.