How do you slice a glass bottle with a string?

Question

Someone saw this in Knowledge Sponge, a show from Korea.

Answer 1

I did it many times when I was about 14. Take a string and soak it in gazoline. Tie it around the bottle where you want a cut and set the string on fire. After a while, when gazoline burns, dive the bottle into a cold water. Bottle will crack exactly under the string. I was successful in about 7 out of 10. Be careful not to cut yourself on the very sharp edges where the bottle was cut. I usually used a rough sand paper to smooth the edges so that you don't injure yourself.

Answer 2

The only way I know is:
1st heat the bottle to almost liquid state while bottle is upright position preferably ...and then run a a wet looped string quickly around the middle of the bottle really fast. Do this with a snapping motion. It can be dangerous and must be timed correctly or you can get burned.

Answer 3

Nylon string with diamond dust epoxied to it.