For my third glass fusing class, Stephanie again had a project planned that allowed me to feel a little creative while also learning an important glass lesson. This lesson concerned volume control. As I described in my first fused glass feature, glass moves - expanding and contracting - when it is heated. This can mean that a piece won’t necessarily be the same size going in the kiln as it is when it comes out. Of course, if you know how to control your glass volume, then this won’t be a problem.

The best way to have an understanding of volume control is to see the results different temperatures can have on similar looking pieces. I was instructed to create four pieces. Three of the pieces should be duplicates while the fourth piece should be the same except the bottom layer should be doubled. Then the four pieces would be fired at different temperatures. This would allow me to see how different amounts of heat can affect the same piece of glass.

After digging through my glass scrap box, I started cutting and pasting together a simple geometric design of yellow, dark green, and pale pink glass squares. I pasted these to a larger square of clear glass. The fourth piece is the same except I used two piece of clear glass on the bottom instead of just one.

Then each piece was fired at a different temperature. Unfortunately, pictures don’t do justice to this experiment since it is helpful to be able to touch the finished pieces. However, I’ll try to do my best to describe how each turned out.

Piece 1: Fired 25 minutes at 500 degrees F

The small, colored squares which were glued on top of the larger, clear square of glass are now "tacked" on. Though they are stuck, or fused, to the bottom piece, the smaller squares have changed very little.

Piece 2: Fired 25 minutes at 900 degrees F

This looks very similar to the first piece except the smaller squares have gotten a little larger. They have the appearance of candy that has melted. The lines between the squares are tighter though you can still feel the groove between the pieces with your fingers.

Pieces 3 and 4: Fired 25 minutes at 1350 degrees F; then fired 25 minutes at 1600 degrees F

This high temperature creates a piece that is almost fully fused, meaning that all layers of glass are close to becoming one layer. Piece number 3 had only one bottom layer. If you look carefully, you’ll notice the sides of the piece are bowing in a little. It is no longer a perfectly square piece.

Piece number 4 had two bottom layers of clear glass. At this temperature, the two bottom layers have completely fused together to form one nice, thick piece of glass. The small squares on top - especially the green and yellow squares - feel as if they have almost completely melted into the bottom layer. The sides are still nice and straight, though the whole piece did shrink in width about 1/8th of an inch.

What did I learn from this lesson?

Comments? Questions? Ideas? Share them on the jewelry making forum.

All graphics created by Tammy Powley.

Previous Features