Glass meant for shelves

[Maryar]

In my kiln working experience I've only used compatible fusible and some stained glass(by itself).
I have someone who wants to sell glass to me that is meant for shelving. They use some type of clips to secure each piece to form clear cubicle type of shelving. It seems to be a bit thicker than standard fusible glass.
Anyone with experience with this type of glass in the kiln?
Will this type of glass score and cut straight? It isn't quite as thick as double thick.
How will this be different in the kiln? Will I need to go a bit hotter, longer hold times or a different annealing schedule?
Mary

[Brock]

It's probably tempered.

[Brad Walker]

To expand on Brock's comment, it's almost certainly tempered glass, which means it's float glass. Tempered glass cannot be cut, but if you heat above it's annealing point (around 1000F) it will lose its tempering and become regular float glass. It will fuse and fire a bit hotter than Bullseye or Spectrum and will need to be annealed at the higher temperature.

You can buy used shelves like these fairly inexpensively (a few dollars a square foot, sometimes less), so don't spend a lot to buy it.

[Kevin Midgley]

Don't pay anything for it. Inevitably it will be deeply scratched. Once bought 2 tons of glass shelving for $100 and that was NEW and unscratched.

[HEIDI in Wa. state]

I was given some of this type of glass a few months ago. I did screen print on it. After it was fired, I sandblasted then slumped. Worked great. Still can't figure out the whole "tin side" thing. I would not have paid for the glass, but has been fun to play with.

[Bert Weiss]

My everyday glass is 10mm float. I anneal it about 80° hotter than Bullseye. If you have polarized filters, they would reveal white dots in a pattern over the glass, if it is tempered. I cut this glass with a 134° glass cutting wheel. I always paint the glass wIth kerosene before cutting. is generally easier for me to work with in the kiln, than thinner glasses as it slumps and picks up texture easier because there is more weight pushing down. Float is quite a bit stiffer than Bullseye or Spectrum, so working temps are at least as much hotter than annealing temps.

If the glass is tempered, you can wrap it in plastic and pop it, then make castings with the broken frit that results. There is a pretty steep learning curve for doing this.

[Keoni]

What the others said, plus:
- It will cut and snap straight, use lubricant on the glass
- Start with standard bullseye schedules with +80F for all steps
- Float is prone to devit, especially if you do not clean it well
- Since you have no idea which factories the glass came from, odds are the sheets will not melt together due to different COEs. If you work within same sheets you will be fine.

Best,

Keoni

[Morganica]

Shelving glass is usually tempered, but not always, and if you don't have a polarimeter setup, there are other ways to tell. If you're lucky, tempered shelves will have a tiny white, circular imprint, usually near one of the edges, that says it's tempered. If not, any shelf you see with a corner chipped off, or a divot on an edge somewhere, is most likely not tempered and can be cut up and fused as needed.

If the shelf is ding-free but scratched, it's quite likely tempered--one way to make sure is to set the glass flat on your cutting table and try to score it with your glass cutter. Tempered glass (and glass that has some sort of protective coating/lamination) may scratch but it won't really score, and the cutter will sound/feel like it's going over a waxy coating. It won't break, no matter how hard you press with the breaking pliers. Non-tempered will score with that satisfying scrrrriiitch, and you'll be able to break it.

Shelves are generally 1/4 inch or thicker, so take your time breaking it--press on one end of the score firmly, and watch the break progress. If it doesn't break or seems to get hung up, don't force it. Turn it around and press on the other end. Sometimes you may need to rap a couple of times on the underside of the score.

If the glass is tempered and will fit in your kiln, you can untemper it pretty easily--take it up to about 1100F and turn off the kiln, letting it cool naturally. (You may need to anneal thicker pieces) If you want to use the tempered glass as-is, pop it into a drawstring garbage bag, close it, and then whack the corner/edge with a hammer a few times. (I usually just take it out into the garage and drop a corner on the concrete floor) It will shatter most satisfactorily into crumbles and shards. I never mix sheets--they can have different compatibilities--so I'll usually empty that bag into its own container and label it.

This glass is very stiff in a kiln--you won't just need higher temps, you'll usually need more time, too, to make it slump into a mold. And it tends NOT to flow together seamlessly, so you'll most likely see where each piece was even if you fuse it. I have an old blogpost that talks about using tempered shards and crumbles:
http://www.morganica.com/bloggery/2007/ ... ds-series/

BTW...I'm not sure I'd pay much for glass shelves unless they were especially thick or of an unusual color. I generally get mine for free, as scrap from remodels and such.