From the page: The bottle that still shines
Idea 9
Fire-string glass cutter
Cutting glass with thermal shock is an old workshop technique, used by artisans long before it became trendy. Glass doesn't really "break": it expands and contracts with heat, and when you concentrate the heating along a single line, the tension makes the separation happen exactly there, in a clean circular cut.
What you need
- A clean, dry wine bottle
- Cotton string or twine
- Fuel alcohol or acetone
- Matches or a long lighter
- A container with ice-cold water (the colder, the better)
- Fine sandpaper or wet sandpaper (grits 120 and 220)
- Gloves and safety glasses
How to make it
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1
Soak the string in alcohol and wrap it tightly around the bottle at the desired cutting height — the tighter it is, the more concentrated the heat.
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2
Light the string and rotate the bottle slowly to heat the line evenly, without letting one spot get hotter than the others.
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3
When the string burns out (about 30 seconds), submerge the bottle head-down in the ice water — the thermal shock makes the glass part perfectly along the heated line.
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4
If it doesn't come apart on the first try, repeat the heating and dipping; never force it with your hands, or the cut will come out crooked or shatter.
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5
Sand the cut edge with the wet sandpaper, first coarse grit then fine, always wet and in circular motions, until it's smooth to the touch.
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6
Wash the glass thoroughly before using it — whether as a drinking glass, a candle holder, or a small vase, the edge needs to be 100% safe.
Finishing touches
a higher cut makes a succulent planter, a mid-height cut creates glasses for juice or cocktails. For a rustic look, sand less and leave the edge slightly frosted.
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