Thursday, October 06, 2011

Glass Breakage!

That’s what I get for bragging on my technique for embedding glass into silver. I’ve never had cracks before, but here they are, right after I opened my big fat mouth.
Sunbird Necklace
Yesterday morning I took photos of the pendant and all was well. As I was constructing the necklace to hang it, I noticed a flash of color from the glass that made me pause. It appeared to be a fine crack starting from the back of the glass and propagating toward the surface.
Sunbird Crack
As the day wore on, the crack propagated, and more formed. There are multiple possible causes.

  1. Perhaps the mounting in this case was too tight. I left a bit of space all around the edges, as usual, so I suspect that’s not the cause.
  2. The back of the pendant was not completely flat, because of deformation caused by the bezel cup on the front. When viewed from the back, there is actually a depression where the cup is attached. I believe it’s more likely that non-uniformity of stresses across the glass could cause the breakage.
  3. Finally, I did some things differently in the enamel on this painting. Specifically, the enamel is much thicker than usual. Because the cracks really appeared to emanate from the back surface of the glass, where the enamel was applied, it makes me think this may really be the issue.
So, you can be sure I will be much more careful in the future, as I try to figure out these factors. Meanwhile, I’ve looked up the tricks of the trade for “healing” cracks in glass. It seems that windshield cracks are often mended by applying a resin to the surface, so I will see if a clear resin coat here will make the cracks less apparent.