One of the early assignments in the accreditation program for Hadar’s Clay teachers involved having to make a sealed, hollow bead, and to fire it. (There’s more than that, but this post is only about that part.)
Of course, who can make just one? I did restrain myself: I made only two. Both are “lentil” beads. One was made from Quick Fire Bronze (which I’ve happily used for ages now), and one using Brilliant Bronze (which is newer to me, and not always successful but one I’ve been determined to master). I made all four “pieces” (both sides, both beads) the same size (diameter and thickness). I did drape the Quick-Fire one over a “steeper” curve than I used for the Brilliant Bronze. After completing the rest of the construction process, I fired them (along with several other pieces I was making for the Western PA Garden Marketplace on April 20). Shown, above, are the results.
The Quick Fire one is shown to the left. It sintered and looks great. It held its curvier-shape well, the seams held, and the kiln gave lovely colors (that, for this exercise, will eventually disappear…).
The Brilliant Bronze one is shown to the right. All the seams held together, no cracks appeared, and it appears to have sintered. Well, to be honest, it appears to be over-fired! It has a rough, sort of pitted, almost bubbled surface. Its edges shrank an extra amount, resulting in a sort of “rim” the whole way around it. Worst of all, perhaps, it slumped a bit: its shape no longer has a nice, even, slight curve to it. Instead, it sort of bulges off to one side (which is hard to see in the photo here).
How did this happen? Well, I knew that Brilliant Bronze should be fired about ten degrees lower than the “other” bronze. But there are several “other” bronzes! And I had a copy of Hadar’s shrinkage-rate chart that led me to believe that it could be fired at either the mid- or high-fire range — and there is a “bronze” that fits the bill for “other” at each of those!
So, here’s the secret: If you EVER have ANY sort of problem using one of Hadar’s clays, first be sure you have the latest information! Always go and check her blog (look at the list on the right side of the screen there). Apparently I had missed that there’d been a typo in an early version of the shrinkage chart, so I had not gone to grab the update. The chart that’s out there now makes it clear that Brilliant Bronze is a mid-fire formula only. Meaning I have to fire it a bit lower than the Quick Fire Bronze.
So the next time I fire Brilliant Bronze, I’ll just lower the firing temperature a few degrees more, and look forward to an even more successful outcome.
In the meantime, though, I have a collection of pieces with butterflies, with roses, and with hibiscus flowers that I made out of Quick-Fire Bronze XT (the high-fire bronze formula) that are calling out to be fired next. Here’s hoping!