Glass Melting Help!

[mogabj]

Hi all!

Just found the site. Looks like a great resource.

So here's the deal. I have been cutting glass bottles to make drinking glasses and I am trying figure out if there is a way to melt the rim so that I don't have to sand each one by hand.

I've been trying to use a propane torch with a pencil tip, but the bottles keep cracking.

Is there some trick that will make this easier? Do I need a different torch? Should I try cutting them differently? Am I just dreaming too big?

Any help would be greatly appreciated!

Thanks!

~Jeff

[Johan]

Here's a link to a similar thread... http://www.talkglass.com/forum/showt...=glass+bottles


i would imagine it would crack everytime.

[Shatner]

How are you cutting them? Be careful about glass dust, if you aren't aware already.

[ACE]

i've never done it like that before. it sounds dangerous to make AND dangerous to use.

on the other hand, i have made a few sets of glasses out of beer bottles by bringing them up in a hot shop garage, puntying the bottom, and opening up the lip hot. you don't really need a lot of glassblowing experience to pull it off- maybe you have acess to rent space somewhere?

[HiAltitude]

Some bottle cutters are pretty easy to use. I've cut down bottles for brush and pencil holders. I like to hand-engrave pictures on the sides. You can use a glass grinder for that edge, but yeah, hand polishing it would be a pain.

Of course glass dust is always a concern, even if you're just grinding something down for stained glass. Wear a proper respirator and eye protection when grinding or engraving or working with frit. lecture over.

Seems like a kiln would work better than a torch here?

I've fused coasters out of bottle glass, no problem. As long as you don't mix the glass from different bottles, glass from one bottle is compatible with itself. Supposedly, the COE is somewhere around 80. You should be able put your bottles in a glass kiln, heat them slowly (300 F/hour)up to fire polish temperature. I've done that with COE96 glass: fuse a bunch of stuff on a 10" clear circle, cut it back to circular, and then fire polish the edge in the kiln. I've also combined the fire polish stage with curing gold paint on the glass.

Maybe there are better instructions over at the warm glass site. Fusing is "warm glass". lol

[jr23]

The time I seen the vid of a guy using a natty, he had a turntable you can say all you want about it being a special rotation device but it was a turntable. He would make a scratch about half inch then set it down and while it was spinning he would put the tip of a oxy flame right next to the glass and it would pop after a few rotations. After that he set a very bushy annealing flame and worked the lip tell it smoothed out. I would think the next step is in a kiln for a little annealing action and its over!

I have also watched u-tube vids of a factory taking bubbles and cutting them in half using the same tech, they had for or 5 of them in a row cutting by flame and then a worker moved them to a grinding station. And worked the lips cold. They where making goblets

[Greymatter Glass]

I've seen it done on a turn table (hand made from a lazy susan and a slow gear motor)...

put a coffee can full of sand on the turn table, mainly for height adjustment, and then position a very soft flame on the very top edge of the lip, about 1mm higher than you think you need. The right flame can both pre-heat and fire polish the glass with minimal stress induced.

A better set up would be to have 3 turn tables, one to preheat, one to polish, and one to cool down on with a smaller flame.

[mogabj]

Thanks for all the tips folks. I'm gonna start working my way through them and I'll report back on my findings in the weeks to come.

As far as how I am cutting them, it is a bit archaic. I score the bottle then heat the score with a candle and run cold water over it.

Some of my issues are that I live in a small apartment, and don't have access to a kiln or anything like that. When using the torch, it was on my back patio. So nothing too extravagant here. I have been using masks and eye protection, but thanks for worrying those who mentioned it.

Hopefully I'll be back in a few with some findings!

If anyone has any other ideas or suggestions please let me know.

~j

[wahoo]

I do it the almost the same way jr23 describes except I anneal first. Bottles are run though a conveyor annealer, basically just enough to not get them to crack. Then I chuck them up in the lathe, a tool I would assume you don't have, mogabj, but can understand, and score them all the way around. I then shock them with a hydrogen/oxy flame and pop, off comes the top, reduce ( less oxy) the flame and polish. flare if desired. google any terms you don't understand.

[ALIEN!]

I would warm them up in a kiln, then open the kiln and flame polish the rims with a hand torch (120$) while they're still in the kiln.