Safety first! It is a wise idea to use gloves (with good grip), safety goggles, and a dust mask. While this is the easiest, and I think safest, way to cut glass, you still need to take precaution because glass can be unpredictable. You are going to want the use the dust mask especially when sanding.
What you will need:
- Empty and clean bottles
- Glass bottle cutter (like mine!)
- Safety Goggles
- Dust mask
- Medium to coarse sand paper
- Hot water
- Cold water
Adjust your glass cutter to the right height and width of your bottle and where you would like to make your new glass.
The important thing to remember when adjusting your glass cutter to your bottle is to try to be as close as possible to a 90° angle to get a clean cut.
With your right hand, hold the glass cutter steady while applying light pressure and slowly spin the bottle with your left. You should be able to hear a light scratching noise as the glass cutter makes a small etching into the bottle. You only need to make this line once. Going over the line can lead to more mistakes, unevenness, or weak spots in the bottle where it will break.
After you have made the etch in the glass prepare you hot water. Over the sink, and low in the basin, pour a small stream of hot water over the etching. Do this for about 10 seconds. Quickly transfer bottle to be under a stream of cool water from the faucet. Repeat. It should only take 2 times to have the glass quickly and cleanly break apart, but continue until the top of the bottle gently pops off.
You can see that you will get a very clean break with minimal effort. All you need to do now is sand the edges of your new glass so it is safe to use. Using the sand paper, run the paper along the edges (inside and out) until smooth to the touch (be careful trying this out). It took me about 5 minutes to get each glass smoothed out.
Voila! New glasses from old bottles!