By guest, Mar 2 2014 08:55AM
As a starter for my blog, I thought I would answer the first question everyone asks... "What is fused glass?"
For over a thousand years, the craft of stained glass changed very little. Windows in churches were made by cutting small pieces of glass, coloured at the manufacturing stage using various metal oxides and rare earths to give a palette of differing hues. The details, like faces, folds of robes or inscriptions were painted on using iron oxide and powdered glass, and fired in at about 670* C. These pieces were then assembled into the finished window using an "H" section lead came, and the joints where one came met another were soldered. The whole window was then sealed using a sloppy, black putty to keep out the rain & wind.
Only in the last couple of decades has the design of glass panels had the ability to change dramatically. This is mostly because technology is now able to give a much more controlled firing cycle, which is required when firing various different colours of glass together to make a design. This is called fused glass. The different colours must be compatible, that is to say, in technical terms, that they must have the same "coefficient of expansion" (CoE). This means that the different colours melt and cool at exactly the same rate, otherwise the finished work will have stresses in it, (which as a worst-case scenario means that it will crack or explode as it cools!)
The glass used must therefore be of the same make, and guaranteed by the manufacturer to be suitable for fusing. Different makes will have different CoEs so cannot be mixed. Below is a small panel made in this way, with a clear glass background and coloured pieces laid on top .
Alternatively, after a piece has been fused, it can be gently "slumped" into a mould in a second firing at a lower temperature. This will give you a bowl, dish or other usable 3D object.