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About angela_w

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  1. I know you said high fired, but in my experience I've found it's a lot easier to sand at the bisque stage if possible. The 220 wet-dry sandpaper works well but doesn't hold up long on the high fired porcelain—you get more mileage out of it at the bisque stage. I make a lot of unglazed porcelain beads and small sculptural forms, and my process is to use fine steel wool on bone dry greenware (if needed, wearing a mask), then after bisque firing I wet-sand any pieces that aren't as smooth as I'd like using either the diamond pads linked above, or sandpaper. After the final firing, if anything feels rough I might sand it again. A three step-sanding process is obviously a bit tedious, but for very special pieces it's worth it for the amazing buttery finish. Also if you happen to be making small rounded forms, you could use a large rock tumbler with water and some aluminum oxide powder which is much, much easier than manually sanding them. This could be done at either the bisque or high fired stage depending on how much material you want to take away.
  2. Hi, Earlier this year I was making unglazed ^6 porcelain beads and fired them all together in an unglazed porcelain bowl. I never encountered any problems with fusing together. Once or twice I had to tap them a little bit with my finger to loosen them up, but they always came out fine. I also just fired some flat ^6 stoneware discs for another potter at my studio (flat circular slabs, fired in a stack of 4 or 5 deep) and they came out fine as well. I had to pull some of them apart, but it was easily done with my fingers, I didn't need to use a mallet or chisel or anything like that. If your work isn't super paper-thin delicate you'll probably be fine... but of course it's always a good idea to test before firing a whole kiln that way.
  3. Wait, Norm, I'm a bit confused now... wouldn't that mean that glazes would be more likely to shiver or dunt on Frost, not more likely to craze?
  4. I'm sorry I can't offer any technical advice (as I'm also a glaze newbie), but I will say that I just tested Glossy Base 1, also with a slow cooling, and found the result to be more of a smooth, satiny finish—not matte, but definitely not a super shiny gloss. In my testing, I found both "Glossy Clear Liner" and "Glossy Base 2" to be true gloss finishes. I'd definitely recommend trying Glossy Base 2 if that's what you're looking for.
  5. Thanks so much for all your comments. The point about fixing the tiles where the crazing is furthest apart is really helpful, it makes perfect sense when I think about it… but I hadn't thought of it! I am going to focus on trying to fix tiles 12 (glossy), 11 (satin), and 6 (matte) and will post results back here when I have them. Also, I am going to fire some test tiles without any glaze on them, to see what happens when they're subjected to the oven/water test.
  6. Hi, I am a total newbie to making glazes and I just ran some tests at ^6 on Laguna Frost. My objective was to find a clear glaze that didn't craze, and I tried a few glossy and a few satin/matte options hoping to find some success. To test for crazing, I used a procedure described in Mastering ^6 Glazes, where the sample is heated in an oven at 300 degrees, then quenched in water. Then I used a blue sharpie marker to reveal any cracks that formed. All of my samples crazed after this test, so I am hoping to get some advice on how to interpret the results. I've attached a couple images of the results. The tiles are arranged in order of the expansion coefficient (as generated in GlazeMaster), with the lowest on the left (6.29) and the highest on the right (7.16). The tiles labeled 9, 6, and 11 are satin/matte and the rest are glossy. Tile 15, on the left, is the low expansion recipe from Mastering ^6 Glazes, which I had been optimistic about since the book suggests it won't craze on the majority of Cone 6 bodies. I've read that adding silica will help solve crazing issues, but since even the low expansion glaze crazed, it leads me to wonder if I am doing something else wrong that is causing problems with the clay body itself? I bisqued the tiles to ^04, but did not do any sort of controlled cooling on the bisque. Also, the cracking seems to extend pretty deep into the porcelain body, as shown in the detail image. I added more ink to the sample on the unglazed portion to reveal the cracking. Is that a normal byproduct of crazing, or is it possible the body itself is cracking and the glaze defect is actually appearing as a result of that? A few more details: The witness cones on the same shelf as the test tiles show the 6 cone bent properly and the 7 cone just starting to lean. I tried to do a controlled cooling using a portable pyrometer (it's a manual electric kiln) but suspect I went a bit faster than is recommended in M^6G. When I opened the kiln to take everything out, I got a reading of 185F on the pyrometer, so it seems that should have been a safe temperature. Any advice on next steps I should take would be appreciated. Adding silica to the glazes is on my list, but are there other things I should be considering? Thanks in advance for any help.
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