Beads Breaking, Thermal Shock?
 

The weirdest thing just happened. I made a bunch of beads about a month ago. Simple black lozenge. I was starting to string a few and get a few ready to etch and they broke! Right down the middle. I didnt feel or notice any lines or cracks. I did anneal them. Ive made this type of bead before. Any ideas about whats going on? How can I check the other beads to make sure they dont break? I'm getting ready to do a show in a few weeks. . .ughhhh

If it was only one glass used I would guess it was just thermal shock. The lozenge shape, because it doesn't have a lot of glass on either side of the mandrel, can be prone to thermal shock, even when you think you've given it enough heat on each side.

I know when I am removing the chill marks and I spend a liiiiiitle too much time looking at the bead after taking it out of the flame, I have the same thing happen. If you know that's not the problem, you might need to slow the ramping down process in your kiln. Might just be a little quick for thin beads.

Thanks Lori for your quick response. I've made a ton of these beads, usually if they break its when I'm cleaning them. not when they've been sitting around. I'm going to try to knock the other beads around and see what happens.

When you are taking the bead from molten hot to cool enough to go into the kiln without getting kiln marks count how many times you flash it back in the flame for a moment, it helps to mark how much time has passed and to learn at what point (or number) is the best point to put the bead in the kiln.

you may also want to check the thickness of the glass around the mandrel holes as that can also cause cracking if too thin.

i'd run all the suspect beads through another slow, conservative annealing cycle to ensure it's not an annealing issue. Then (instead of "knocking them around", lol, as that may cause chips or hairline fractures), take the re-annealed beads - wait a day or so to ensure the cores are at room temperature - and place them in a bowl of ice water for about an hour. any that don't survive just toss...