MollyMac Posted June 19, 2020 Report Share Posted June 19, 2020 Please look closely at the pic I provided. This is a stoneware sculpture with underglaze and I just pulled it out of the electric kiln after putting Amaco F10 Clear on it and firing per instruction at program Slow Glaze. Why do I get this foaming in the crevices? Link to comment Share on other sites More sharing options...
neilestrick Posted June 19, 2020 Report Share Posted June 19, 2020 Probably the glaze and/or underglaze is too thick in the crevices. Did you brush on either/ both? It's difficult to keep brushed on applications from getting thicker in low areas. Link to comment Share on other sites More sharing options...
MollyMac Posted June 19, 2020 Author Report Share Posted June 19, 2020 I brushed it on, 2 coats. It is a deply textured piece, but there has to be more than that - it looks like it's bubbling over the surface too now that I see it up close in that pic. Here is another pic. Link to comment Share on other sites More sharing options...
MollyMac Posted June 19, 2020 Author Report Share Posted June 19, 2020 In response to myself (haha) I just found this on Google: "Fire the glaze higher or adjust its formulation so that it melts better and more readily heals surface bubbles. In a slow-firing setting, you may need to soak the kiln longer at maturing temperature to give the glaze a chance to heal itself." - This brings me to another question, can I re-fire this at a higher cone and let the bubbles come out ...without damaging the sculpture? Link to comment Share on other sites More sharing options...
Bill Kielb Posted June 19, 2020 Report Share Posted June 19, 2020 1 hour ago, MollyMac said: In response to myself (haha) I just found this on Google: "Fire the glaze higher or adjust its formulation so that it melts better and more readily heals surface bubbles. In a slow-firing setting, you may need to soak the kiln longer at maturing temperature to give the glaze a chance to heal itself." - This brings me to another question, can I re-fire this at a higher cone and let the bubbles come out ...without damaging the sculpture? My opinion, not likely. All If not most of the flux and melting has occurred in the clay and glaze so usually refining often stresses the ware and does not necessarily smooth out the glaze. For me a refire success rate might be 2 in 10. My best luck with these repairs has been to figure out a workable solution using lowfire glaze and firing down. With respect to underglaze bubbleS, I spent about six months testing and formulating to conclude the bubbles I was seeing, originally thought to be overfired, actually tested as underfired. So to that end We reformulated our clear glazes for use over underglaze to melt more readily. This was consistent with those that often mix their underglaze with some Fritt. We also noticed, underglaze application thickness as well as certain colors appear to react more refractory, and have bubble issues. We have a matte and gloss clear that we have used for some time now. Each has had its Boron increased so it begins to melt closer to theoretical cone 4. It was formulated and tested on our porcelain though. I am not a fan of fire and hold though. Just never has worked well for us. Link to comment Share on other sites More sharing options...
MollyMac Posted June 19, 2020 Author Report Share Posted June 19, 2020 OH thank you Bill! So what brand of clear glaze are you referring to and where can I buy said glaze? Link to comment Share on other sites More sharing options...
Bill Kielb Posted June 19, 2020 Report Share Posted June 19, 2020 1 minute ago, MollyMac said: OH thank you Bill! So what brand of clear glaze are you referring to and where can I buy said glaze? We mix our own, it was the only way to get the matte and clear we wanted with known theoretical melting points. As I said, works on our porcelain so no crazing. Happy. To give the recipes though but you will need to test with your body. Link to comment Share on other sites More sharing options...
neilestrick Posted June 19, 2020 Report Share Posted June 19, 2020 1 hour ago, MollyMac said: In response to myself (haha) I just found this on Google: "Fire the glaze higher or adjust its formulation so that it melts better and more readily heals surface bubbles. In a slow-firing setting, you may need to soak the kiln longer at maturing temperature to give the glaze a chance to heal itself." - This brings me to another question, can I re-fire this at a higher cone and let the bubbles come out ...without damaging the sculpture? If you're not happy with it as is, you've got nothing to lose by refiring it. Give it a try and see what happens. Link to comment Share on other sites More sharing options...
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