Couple of big bubbles during slump
Posted: Tue May 27, 2003 12:37 pm
Okay, I did a large tile platter (the ones where you stack up glass tiles, slowly getting smaller, ranging from 4-5 layers of tiling). It had a 20" round base of two pieces of clear and then the many tiles were on it. Made it through the fusing fine, decided to sandblast the front of the piece to get a smoother shinier finish. Here is where the problem happened.
I was extremely conservative on the slump, into a 20" round ball surface mold from bullseye. I took it 50 dph set 1100 hold 30 minutes (it was already fully slumped at this point), but I wanted to take it to 1325 for just a second to ensure I got a nice fire polish as well. Then I went 225 dph set 1325 no hold and went right back down. I check back on the piece when it was at about 12something and all was well. The next time I looked three large bubbles had formed, 2 were a bit smaller about 2-3inches and one was large about 4-5 inches. They are all sort of in the center, though none are around the one hole that is drilled in the mold.
I was devastated when I saw this. Thought maybe I could squeeze them out, so I held at 1130 for two hours but it didn't help. Just let it finish the firing and annealing schedule. Now we are up tp the present and I want to get rid of these bubbles by just firing it on a flat surface. I have never done this and wanted to know how to go about it. Do I need to do anything special, such as fire on fiber paper or thinfire to help the air get out from those three bubbles? I am just a little scared that they will get worse instead of better. I was thinking of following my conservative schedule of 50 dph set 1100 and hold it for maybe 3 hours or so.
Any and all advice welcome.
Thanks
Aimee
AKA Anea
I was extremely conservative on the slump, into a 20" round ball surface mold from bullseye. I took it 50 dph set 1100 hold 30 minutes (it was already fully slumped at this point), but I wanted to take it to 1325 for just a second to ensure I got a nice fire polish as well. Then I went 225 dph set 1325 no hold and went right back down. I check back on the piece when it was at about 12something and all was well. The next time I looked three large bubbles had formed, 2 were a bit smaller about 2-3inches and one was large about 4-5 inches. They are all sort of in the center, though none are around the one hole that is drilled in the mold.
I was devastated when I saw this. Thought maybe I could squeeze them out, so I held at 1130 for two hours but it didn't help. Just let it finish the firing and annealing schedule. Now we are up tp the present and I want to get rid of these bubbles by just firing it on a flat surface. I have never done this and wanted to know how to go about it. Do I need to do anything special, such as fire on fiber paper or thinfire to help the air get out from those three bubbles? I am just a little scared that they will get worse instead of better. I was thinking of following my conservative schedule of 50 dph set 1100 and hold it for maybe 3 hours or so.
Any and all advice welcome.
Thanks
Aimee
AKA Anea