By hotpotnorge, Jan 8 2012 03:48PM
During our demonstration of the Hotpot microwave kiln we got several times the next two questions. Which is exactly the same questions I did have when I started to use the HotPot microwave kiln.
What does the COE.. in glass fusing stand for?
COE stands for Coefficient of Expansion and is used in the world of glass fusing as a compatibility code.
If you fuse glass always stick with the same COE code.
For example if you put COE 90 and COE 96 in a design and fire it in your HotPot or fusing oven, the difference in expansion will cause surface tension and make the glass crack.
This will happen when the glass expands during firing or contracts under the cooling down period.
At the same time it tells something about the hardness of the glass. The lower the number the harder the glass. For example, an ordinary bottle has a COE 38 code and a lamp worker uses much softer glass like COE 104.
Can I use the glass that I’ve got in the barn in the HotPot?
The problem with fusing 'found' glass is that you have no idea what the COE is.
So it isn’t recommended to use this with the glass supplied in the HotPot starter pack.
Hope this will help and if you got more questions about the Hotpot microwave kiln let me know and I’ll do my best to answer them.