how to prevent cracking when cutting a glass wine bottle in half?

I was attempting to cut a glass wine bottle in half to make some vases & other stuff.  I bought a bottle scoring kit (i think armour brand from Micheals Crafts)  The scoring worked OK, i don't think it scored well in a few places, but the tapping portion the kit said to do to seperate the halves didnt work at all.  I looked up online & it said about filling the bottle with boiling water then running an ice cube around the score line . . . this worked & split the bottle into 2 pieces as i wanted - only problem is it left a few cracks running vertically from the score line =( I can't use either piece now.  Is it just luck & practice makes perfect or is there a way to acheive this without cracking the bottle halves?  Any help is much apprecaited!

Burf7 years ago
I was having the same problem a few months ago and found a how-to video on YouTube that actually works.  I practiced on a few bottles to get the technique right but now I can do five or six bottles at a time and rarely have more than one that I can't use.
Here is the video:

http://www.youtube.com/watch?v=sFXngPx3w3M
seandogue Burf7 years ago
nice! +1
Another classic method is to wrap a wire round it, and connect it to a big battery. The wire flash heats, and the shock cracks the bottle.