2) Hot bath
3)Add boron, lithium, or titanium
Wait, I'm confused. Let's stick to one sort of tension: the surface tension of glaze.
One of my glazes, which I got from Brad Sondahl's website, is a marvelous glassy white. Everything you want in a liner glaze: smooth, forgiving, opaque; but it exhibits a surprizing level of tension, to the point that it will split any pot which is not glazed or only partially glazed on the exterior. So that's not good, for a vapor-glazing potter, right? Opening the kiln to shattered dessert dishes increases my personal tension like you wouldn't believe. (I was mistaken in the linked post; the shattering did, in fact, occur during cooling.)
First, some links. I have a general understanding of glaze tension/ compression; nevertheless; on my list of things to do this weekend (which is starting to get looong...), I mean to thoroughly peruse these articles. If you aren't a potter, or you buy commercially made glazes, these articles will bore your eyes out. Ooops, gross accidental meaning! Bore you silly, let's say, instead. For potters who mix their own glazes, the answers to many glaze-flaw mysteries lie within:
Read them already? No, me either; but I am supposed to be loading a kiln, so I am going to leave off for now. I'll summarize when I come back, along with a solution (she said, optimistically!) to my specific glaze dilemna: how to decrease the tension of Magic White.