nancylee Posted May 1, 2017 Report Share Posted May 1, 2017 Hi, This is a commercial Ketchup glaze below, Cerulean above. Previously, it came out beautifully, but the last two firings i got pitting. I am firing to cone 5, and there were no pits or bumps or any mats in the glaze when it went into the kiln. I got some pitting in this big plate, also. These are Potters Choice glazes, layered. Why does this happen and how can I stop it? Thanks, Nancy Link to comment Share on other sites More sharing options...
Denice Posted May 1, 2017 Report Share Posted May 1, 2017 Is it a new jar and is it stirred thoroughly. Denice Link to comment Share on other sites More sharing options...
nancylee Posted May 1, 2017 Author Report Share Posted May 1, 2017 Is it a new jar and is it stirred thoroughly. Denice Hi, No, not a new jar, and I stirred it and thinned it, also. Thanks! Link to comment Share on other sites More sharing options...
neilestrick Posted May 1, 2017 Report Share Posted May 1, 2017 I see glazes do that when they're over-fluxed. In glazes you mix yourself that means increasing alumina and/or silica to fix it. You don't really want to mess with that with commercial glazes, though, so the only option is to fire cooler. Try firing cooler and see if that works better. It could be that your previous firing didn't get quite as hot, or the pots were in a cooler spot in the kiln. Did you verify your firing temp with cones? Link to comment Share on other sites More sharing options...
nancylee Posted May 1, 2017 Author Report Share Posted May 1, 2017 I see glazes do that when they're over-fluxed. In glazes you mix yourself that means increasing alumina and/or silica to fix it. You don't really want to mess with that with commercial glazes, though, so the only option is to fire cooler. Try firing cooler and see if that works better. It could be that your previous firing didn't get quite as hot, or the pots were in a cooler spot in the kiln. Did you verify your firing temp with cones? Hi, No, I didn't use cones. I should, but don't. My kiln took a LONG time to get to Cone 5 - about 12 hours. Usually, it takes about 7 hours on medium speed. It was on the middle shelf, however, which seems like it would be the hottest spot in the kiln. So refiring at cone 6 won't fix this? Is there a fix? It was a custom order. Thank you, nancy Link to comment Share on other sites More sharing options...
neilestrick Posted May 1, 2017 Report Share Posted May 1, 2017 No, refiring won't fix that. If your kiln too that much longer than usual then there's something wrong with it. Check your elements and relays and thermocouples. Link to comment Share on other sites More sharing options...
nancylee Posted May 2, 2017 Author Report Share Posted May 2, 2017 No, refiring won't fix that. If your kiln too that much longer than usual then there's something wrong with it. Check your elements and relays and thermocouples. Thank you, Neil! Nancy Link to comment Share on other sites More sharing options...
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