Sunday, March 25, 2012

A Lesson in COE - Co Efficient of Expansion

I made a few painted beads the other day  and said that one was cracked because I thought possibly I held out too long ogling before putting in the kiln to anneal.  Then the other two I made also broke and then I realized what I had done - A really DUH moment for me -    I had used my flat sheet  Bullseye 90 COE flat glass - which I had screened on my pattern and instead of using my Bullseye 90 COE glass rod I used my Morretti  104 COE  -  Trying to use two different COE's caused the problem.   You must use the same COE as the glass can contract at different rates thus causing the cracking.  Just shows you that  after all these years I can still make a simple mistake  with my glass -   you must remember what glass your using . Sounds like mumbo jumbo but it is an essential knowledge needed for Lampworking-

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