Bubbles issue

Hi Arek,

The problem could also be your bisque fire. Perhaps you are not firing hot enough or long enough for good outgassing. It is thought that cone 05 or 04 are best for prep for crystallines. Personally, I fire to 1860 F and hold at top temp for 1/2 hour.

Bill C. Does not bisque fire his work at all and gets marvelous results, but for those of us who do, more heat work is often needed to avoid bubbles in the glaze fire.

Marie

I don't have the experience with crystals that the others here do, but some time back I began generally bisque firing my ware to ^03 to ^02 with a particular schedule I got from Steve Davis at Aardvark Clay. He recommends a final temp climb of 108F/hour to 1922, which equals ^04, but I've found that a little hotter helps prevent dunting and bubbles.

I spoke with Steve at length about some problems I was having, one of which was what you are experiencing, Arek. Steve said he has even gotten some agreement with Skutt techs on the subject of changing their recommendations. Since I started the modified firing schedule, I haven't had much problem with pinholing or bubbles.

You can find a detailed explanation of his bisque schedule here.  I have not followed his guidelines to the letter, specifically the part about using fire brick to prop the kiln lid open till 1650F, because it tends to stress the elements a bit more than I like, and the brick needs to be positioned precisely to keep the electronics from shutting down. But I've had pretty good luck modifying the schedule to 03 - 02, removing the top and bottom peep plugs.

Anyway, take a look at it and see if you think it would seem to help.

Thank you for sharing that, Arek.

And by the way, if anyone has advice contrary to what I posted above concerning bisque firing, please say so. The schedule I created was tailored for wares to address bubbles and pinholes before I got more involved in crystalline work, even though it seems to work for that as well.