If you are interested in the process of creating jewelry using PMC3 and have followed my posts through my success and failures, this is definitely a post you do not want to miss.
In my top three list of metal clay books is Lisa Barth’s “Designing from the Stone”. Not only is her jewelry fascinating and gorgeous, she talks about stuff not even hinted at by anyone else, things like “The Big Squeeze” or doming effect.
The doming effect is what you get when “an unstoppable force meets an immovable object,” as Lisa so nicely puts it. During firing, the metal clay shape shrinks as the binder burns off, and as it shrinks it pulls inward and horizontally. It is this “unstoppable force” shrinkage that traps “an immovable object” like a gemstone in its bezel when firing stones in metal clay. Unfortunately, the openings in the back of the settings are also shrinking and pulling inward, causing the dome. Here is what Lisa has to say about the doming effect and what to do about it: “Nothing, not a darn thing. It is going to happen; it is just the nature of the beast so relax about it. I actually like the doming effect and I do not fight it.”
Neither of my two test pieces domed, and I used the same program when I fired my commission pieces, along with a few other items. I absolutely was not expecting a doming problem as the pieces were so small. Big or small, the Big Squeeze gets them all.
Here is what happened to my commission pieces today during firing:
This definitely was one of the bigger “Oh Shit!” moments of my artistic career.
As there was nothing to be done, I burnished the pieces and then began the long tedious process of sanding with a coarse grit through several successively finer grits. They were pretty, but those domes were bugging me big time.
I decided about half way through sanding that there was nothing for it but to create another pair, although I hadn’t considered how I would prevent another doming. This decision gave me full rein to see what I could do to straighten out the domed pieces and, if I destroyed them, hey, try, try, try again.
I got out my steel and rubber bench blocks, placed the first earring on the steel surface, shield side up, and taking up one side of my wire whacker and my chasing hammer, I got ready to do some damage. The rubber bench block would soften the impact from below while the wire whacker board would soften the blows from above without breaking or flattening the anti-glare shields…well, hopefully.
And it worked like a charm!
There but for my magical faerie wings go I…goodbye domes, hello more sanding!