Today I want to answer some frequently asked Questions. As you might know, we began to make fuseable glass in 2008. We started with COE 90 and later on added a line in COE 96; the two major categories for fusing glass in our industry.

What does COE mean?

COE stands for “Coefficient of Expansion” and is only measurable only in a laboratory where they can measure the changes at the molecular level. For Example a COE 90 glass will expand 0.0000090 inches per degree Centigrade while COE 96 will expand 0.0000096 inches per degree Centigrade.

Can I fuse COE 90 an COE 96 together

The difference in expansion and contraction does not sound much but it is enough to cause stress in the glass. If you fuse glass with different COEs together it might crack in the cooling process and some times even a year later. This is called incompatibility. We here at Wissmach test all our glass to ensure  a successful fusing experience. 

Can I test my glass to find out the COE?

Without the laboratory equipment you can not test which COE a certain glass has but you can test a glass to find out if it is compatible with 90 or 96. You can use 2 polarized lenses or use the Fuse It Test card developed by Petra Kaiser. Find out more about testing your glass in the video below.

What makes glass COE 90 or COE 96?

Glass is made up almost entirely with sand, soda ash, and limestone.  We add very small amounts of other raw materials to get the colors that we want. The quantity of some of the raw materials is adjusted in our formulas to make the glass 90  COE or 96  COE.

 Why does Wissmach fusing glass not devitrify?

Fusing glass can devitrify if not cleaned properly in particular.  We have added some special raw materials to our glass formulas to keep the glass from devitrifying chemically.   All of our fusing glass has been put through a rigorous test, firing at least 3 times and going slowly through the 1300 degree range where denitrification normally occurs.  
Our goal is to make your  glass fusing experience enjoyable.