WarmGlass.com

I want to make some black/white/clear pattern bars. Am I better off using stiff black, or does it matter?

Depends on what you're trying to do. Regular black is a lot softer/runnier/juicier than the white, so it's going to move around a lot more and will tend to shift position far more than the white, a bit more than the clear. It can also really engulf and overwhelm the other colors if you use equal amounts of each.

Stiff black will behave more like the other two glasses, so it'll tend to move with them and be a little more well-mannered about letting the other colors show up.

So...if your pattern bars are orderly, precise checkerboards and such, stiff black will help hold the pattern. If you're looking for wild, swirly effects, use regular black but use a lot less of it than you do of the white or clear.

One thing to also consider: Soft black next to white can be an annealing problem--the black's moving around long after the white has stiffened which can set up stress. You need to very carefully monitor (and probably extend) the anneal schedule. It's less critical with stiff black.

Wow. That is very interesting. I do want crisp lines in these pattern bars, and had not thought about the annealing issue...There are times when I would love the more organic look of the black being swirly and more free-flowing, but not on this project. Thanks loads for the help!