The SDS for the original GLASMA formula 705 does include zinc. The formula for alumina crucibles does not (705E). Still waiting to hear from Bill who is waiting to hear from GLASMA about other possible batches.
Don't you kind of feel like you lose your compass when you mix your own clear. If you use a batched version, at least you know where it sits and can adjust your colors around that. When you mix your own a number of variables are introduced which could cause drift in the expansion of your clear. When problems arise, how do you know it's your color or some variability in your clear? I guess you can mix large batches at once or create cullet from it to "freeze" the formula. Seems like your complication factor would double, at least.