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-   -   Beads breaking in half after annealing (http://www.lampworketc.com/forums/showthread.php?t=309010)

lory 2019-01-10 2:30pm

Beads breaking in half after annealing
 
I keep getting broken beads. I take them out of the kiln and when I put them in water to start loosening them from the mandrel, they break in half.

Eileen 2019-01-10 3:07pm

If they are breaking along the mandrel, it sounds as if they are too cool at some point. Are you going from flame to kiln? You may be admiring them too long, or just letting them cool too long before putting in the kiln.

Three Muses Glass 2019-01-10 5:20pm

Hi Lory, welcome! Need lots more info- glass used, annealing schedule, did they go right in or are you batch annealing...things like that.

KJohn 2019-01-10 6:56pm

breaking in half is thermal, so sorry! that sounds very disappointing. Make sure that they have all over heat before putting into kiln, and they are not too near the door. More info would be great. HTH

Speedslug 2019-01-11 7:00pm

Perhaps they are too small to hold the heat they need between the torch and the kiln.

I tended to forget that the mandrel will suck the heat out of the center of the bead and unless I was religious about putting the bead in the flame at the end for what a lot of instructors called "insurance heat".

When they are real small even 5 seconds between flame and kiln can be enough to install stress that won't show up until you begin to clean them.

Another source of stress is that your kiln is not warm enough or you are not letting the bead soak long enough in the annealing temp range for the internal stress to even out.

Cooling them too fast is yet another way to get these kinds of breaks so double check you cool down schedule of your kiln.


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