How it's done - rendering the glass
Working with recycled glass from bottles is not as easy as you'd think.
The glass varies in quality and thickness and can be brittle or prone to cracking in erratic ways, and there is the fact that wine bottles are often thicker at the bottom and get thinner towards the top. This can make the end product a bit irregular, but that is it's unique legacy and it's essential character. So - finding glass that cuts well, fuses well and looks clear and lustrous isn't always a given. That being said, it's abundant and can be made to look attractive in it's second life.
We start by lopping off the top and bottom of the bottle, trying to maximize the yield by cutting as tall a section as we can get. (for a sauterne or pinot grigio that's as much as 7 3/4 inches but for a chardonay bottles you might only get 4 1/2). We use a simple bottle cutter (PICTURE) to score the bottle at the top and bottom.
Next, we need to break the bottle along the score lines. You can often get to the top score line with a metal tapping tool (which I think gives a lot of control), but the bottom one is darn near impossible to reach, so you will need to use boiling water to induce a stress fracture along the score line.(PICTURE)
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The next cut involves a design decision - if you want the flattened bottle to already be the size of the mold, then the next cut is critical. Why do this? Well, it gives the flattened sheet of glass a nice round edge and eliminates the need to do any further machining to get make the glass fit the mold.(PICTURE)
You will also have made the same decision on the height of the first score line. So let's say you cut a cylinder that's six inches tall, and about 8 inches in circumference and you are making a six by six plate. That means you need to remove a two inch strip of glass from the cylinder. Mark it with a sharpie and hand score it using a firm vertical stroke along the line. (it gets easier with practice.)
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Now it is simply a matter of 'unrolling' the cylinder onto a flat (or textured) surface.(PICTURE)