Glass Compatibility

There are a multitude of glass manufacturers, and different ways of making glass. Since you want to put different pieces of glass together in your projects, you will need to be sure that they are compatible.

Not every piece of glass expands and contracts at the same temperature. This change in the density is known as the Coefficient of Expansion (COE). All pieces you fuse together need to have the same coefficient of expansion (COE).

Here is what a sticker on a piece of Bullseye glass looks like. It indicates that the glass has been tested and is compatible with other Bullseye glass.

So, the first decision you need to make is which COE of glass you want to use in your glass fusing projects. The lower the COE, the harder the glass and a higher temperature is needed for it to begin melting.

Decide which COE of glass you are going to use, and stick with it in all your glass fusing projects. There is a lot of glass that is used for doing stained glass, and it is not tested for COE. So, be sure your glass is designated as fusible glass and has the specified COE. You can not tell the difference by look, so if you do purchase different COE glass, be sure to keep them separately in your studio.

Not sure of the COE…there are only a couple of ways to know if all of your glass is compatible.