Old bottles can be upcycled into useful household items. Remove the tops of beer bottles and they can be used as drinking glasses. Remove the top of a wine bottle and you can use it as a flower vase. Cutting glass with string is surprisingly easy.
Things You'll Need
Lighter fluid or nail polish remover
Bowl of water large enough to hold the bottle
Soak the string for a few minutes in the lighter fluid or nail polish remover.
Tie the soaked string around the bottle at the point you want to cut.
Put on your goggles. Hold the bottle over a fire safe surface and set the string on fire. Allow the string to burn until it burns out on its own.
Place the bottle in the bowl of cold water. The temperature change will cause the glass to break.
Tap the glass gently with the back of a spoon at the break point (the point where the string is wrapped around the bottle) if it does not break.
Smooth any jagged edges with a diamond-coated file. Be sure the glass is wet and well-lubricated when working with a diamond file.
Be sure to have a fire extinguisher nearby when working with fire. Consider wearing fire-safe gloves as well.