What is fused glass?

Fused Glass, sometimes called Kiln Formed Glass is a general term for glass that has been ‘warm worked’ – worked hot enough to soften and combine several layers in to one but not hot enough to be blown. Here is something of an explanation of glass fusing.

At its most simple a glass fuse is where a number of layers of cold, cut glass are stacked and then heated in a kiln to a temperature where the layers ‘fuse’ together to make one piece. Various ‘top’ temperatures achieve different results. A full fuse, where the glass becomes very soft before being cooled, results in a piece where the edges are fully rounded and there is no sign that the glass has ever been more than one piece. A slightly lower temperature will cause the glass to stick or ‘tack’ together – called a tack fuse and here you can usually see the individual layers. A slightly lower temperature still, will cause the glass to soften enough to bend or ‘slump’ and is useful for adding shape to a piece – this process is often used to make bowls.

Many materials can be placed between the glass sheets before firing and these include pieces of metal, metal oxides, chards or powdered coloured glass and even text. When fusing temperatures are reached, some of the ‘inclusions’ undergo a chemical reaction which causes changes in colour/appearance. These changes are a bit unpredictable and sometimes dramatic so the whole process is a sort of alchemy. One example of such a change is the firing of silver leaf which can leave a beautiful yellow stain after being fused.

We tend to work with float (window) glass which is clear with a greenish tinge which give our pieces an organic feel. Float is a most unpredictable glass to fire but very much worth the results. Much of the fused glass that you see in England will be made from combining pieces of coloured ‘art’ glass. Bullseye is a commonly used brand and is made for fusing. We prefer to create our art through the free-er process of ‘drawing and painting’ using metals and inclusion materials (see above) fused between clear, float glass. Our way of working evolved when Sue started fusing glass for work as part of her fine art degree and since then we have been experimenting to push our techniques further. We do, however, use Bullseye glass for making jewellery.

This is a very brief summary of the process as it’s a huge subject – if you are interested in knowing more then why not come along for a days course in basic glass fusing. This is a great way to have lots of fun whilst learning more about glass – to find out more, please use the courses menu at the top of the page. Alternatively this is a great present for any friend or family you have that love glass or crafts or even both!