Making Fusible Flat Glass From Bottles

Bottles before the fusing starts

This is a longer, extended version of a newsletter from last fall. This topic turned out to be one of the most popular newsletters ever, and is still generating questions, hopefully, this extended version will answer those!

The downside of fusing with bottle glass is that it arrives at your studio curved. Sometimes that’s okay, some projects can accommodate the curved glass. Some projects, however, must be made with flat glass.

Making your bottle glass into flat pieces for fusing is relatively easy, there are a few steps:

1. Cut the top and bottom of the bottle off.

I prefer to use a tile saw for this step, but many people successfully use the score, heat and thermal shock method. Once you have the top and bottom cut off, you’ll have a cylinder of glass. (this video shows cutting the top off, the process is the same)

2. Cut the cylinder in half by scoring on the inside (I use a pistol grip cutter) or if your hands are too big, you can saw down the side with a tile saw.  You can score the outside of the bottle, but then you have to put gentle pressure on the score from the inside of the cylinder, which can be tricky.

3. Load the kiln with bottle halves.

One of the tricky parts of loading the kiln is making sure that the bottle halves are far enough apart that they won’t melt into each other. Here’s a quick trick to make sure that doesn’t happen.

Continue until your kiln is filled.

flattening bottle halves

Cut bottle halves before flattening

4. Slump the glass flat

Bottle glass can only be fused a finite amount of times, so we are going to fire the bottle halves just until they flatten, not even enough to round the edges.

Use this firing schedule:

300 F to 500 F – hold 10
500 F to 1260 F – hold 8
0000 to 1060 F – hold 20
Flattened bottle glass
What that gets you:
Each 1.5L bottle melts into two pieces of glass, depending on if it has a long sloping neck (like a white wine) or high shoulders (Skyy Vodka), your glass will measure approximately:
Tall Shouldered 1.5L Bottle
Cut & flattened Skyy Vodka Bottle

2 pieces of glass at about 6″ x 7″ rectangle. This is a Skyy vodka bottle. Your sizes will vary based on where you cut the top and bottom off. There is the same amount of glass in nearly every 1.5L tall shouldered bottle.

Sloped Shouldered 1.5L Bottle

cut and flattened chardonnay bottle

Two pieces of glass at about 6.5 x 5″ rectangle. This is a 1.5L chardonnay bottle. Again your sizes will vary based on where you cut.

750Ml Tall Shouldered Bottle
cut and flattened Jameson Bottle

2 Rectangles of approximately 4.5″ x 6.5″. This is a cut and flattened Jameson Bottle.

750 ml Slope Shouldered Bottle
cut and flattened cider bottle

2 squares of glass approximately 4.5″ x 5″. This is a cut and flattened sparkling cider bottle. The lighter section across the middle is where the glass is thinner.

While the sizes of your cut and flattened glass pieces will vary slightly based on how close to the bottom you cut, and how far up the shoulder you cut, most bottles have about the same amount of glass in them. Hopefully this will give you a quick guide in terms of which bottles to cut and flatten based on the project.
Things to remember:
The two bottle pieces are compatible with each other. Consider storing them together, or marking them in some way to keep track.
If the bottles don’t fully flatten, increase the hold time at the top temperature.
Thanks for reading, hopefully this was helpful for you!