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Melting glass bottles


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It's pretty simple. Do a Google search and you'll find lots of firing schedules. You want the bottom of the bottle to be nice and smooth, so start with a fresh application of kiln wash, as smooth as you can get it. The glass will pick up every little bump. Ideally, use an unwashed shelf and kiln paper.

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Neil is correct, there is a lot of info out there.   The firing schedules will depend upon the size of your kiln.  You need to get your ramps up to a certain temp and then hold, and same with cooling.  A controlled cooling  with help with devitrification, a cloudiness on the glass (like crystallization)  I slumped a lot of bottles when I got my kiln, once I figured out the firing schedule, for a 7cu ft kiln, the bottles paid for a lot of clay supplies.  The material was free (people dropped off their empties at my house) and it was a trend at the time.  Shorter firing time, less electricity, all that.  Now I slump about one load a year, someone wants a bottle for something special.  I really do like finding another purpose for glass bottles!   I have a customer who buys the slumped bottles from me and incorporates them into her stained glass work.

Roberta

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One thing I found out the hard way was to either use really flat shelves or put a little mound of alumina hydrate under the far edge of the bottle if your shelves are at all warped. Bottles can roll, I had a couple roll and fuse together. The alumina hydrate acts as a speed bump to stop the bottle rolling and just brushes off after the firing.

Genesis controller comes with this schedule for slumped bottles.

500/500/15 hold

500/1000/15 hold

600/1250/20 hold

500/1475/15 hold

9999/1100/30 hold

200/970/30 hold

120/750/10 hold

off

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8 hours ago, Roberta12 said:

Neil is correct, there is a lot of info out there.   The firing schedules will depend upon the size of your kiln.  You need to get your ramps up to a certain temp and then hold, and same with cooling.  A controlled cooling  with help with devitrification, a cloudiness on the glass (like crystallization)  I slumped a lot of bottles when I got my kiln, once I figured out the firing schedule, for a 7cu ft kiln, the bottles paid for a lot of clay supplies.  The material was free (people dropped off their empties at my house) and it was a trend at the time.  Shorter firing time, less electricity, all that.  Now I slump about one load a year, someone wants a bottle for something special.  I really do like finding another purpose for glass bottles!   I have a customer who buys the slumped bottles from me and incorporates them into her stained glass work.

Roberta

Got any pics?

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I did glass casting with recycled glass,  I was melting it into bisque molds.   I had to do a lot of testing to find the right schedule and firing temperature and annealing process.   One thing I did find is that most bottle glass is tempered  and will slump but takes a high temp to melt.   I use crushed window glass  for a blue green glass and cheap clear glasses from the Goodwill store for my clear.    The thicker the castings the harder it is to fire and anneal correctly,  my castings are a inch thick and it took 21 hours and that was as fast as I  could go.      Denice

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Long ago in the 70s I was making my own beer . I got the idea of making my own labels with decals and had collected many cases of long neck beer bottles. I was ramping up the run and test fired a few bottles with luster temp decals I had printed-well the tem to flux the decal (cone 019) if I reacll also was the temp that all the necks started to slump over.

I got some great labels on crooked unusable beer bottles.. I gave up glass in electrics at that point.

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