Tempered Glass Shards

[smallbitz]

I've been fusing tempered glass shards and just can't seem to get around the needles on the edges. Fusing into slightly rounded bowl. Any suggestions? Here's my schedule

500/1000/10'
400/1350/17'
full/1015/1.30
250/700
500/300

also tried

500/1000/10'
200/1400/10'
full/1015/1.30
250/700
500/300

both produce very 'needley' edges.

[lorimendenhall]

I was told you are not supposed to fuse tempered glass.

[Alexis Dinno]

I was told you are not supposed to fuse tempered glass.

Huh . . . wonder if I need to throw out my castings and jewelry then. Or wait: was that a moral "not supposed" or a technical "not supposed?"

One of the most beautiful glass objects I own (or have even seen) is a casting from tempered float.

[jim burchett]

Broken tempered glass makes beautiful objects,try going a bit hotter...1450 and see how it goes...float generally fires hotter than art glass.

[Morganica]

Needles on the edges? Wow--I wouldn't think it would do that with your schedule. The edges can remain sharp, however. I typically tack-fuse these at 1380-1450F for no more than 30 minutes with slow ramp up, and at the 1450 mark the edges are pretty rounded. I suppose if you were letting the shards slide down a mold you might get needlepointing at that level. Depends on what you're looking for. Both of these pieces are tempered glass, with radically different schedules. The bowl was a simple tack-fuse which didn't needlepoint, but left some of the sharp edges intact; I simply hit them lightly with a piece of wet-dry to prevent someone from cutting themselves on those points.




Tempered glass is VERY fusible...as long as you accept that it's not going to behave like fusing glass (and obviously never try to fuse it with fusible glass). Processes for the bowl here:
http://www.morganica.com/bloggery/2007/ ... ds-series/

[smallbitz]

Yes, perhaps I'm just not going hot enough. It's not just sharp edges, it's definately needles. I do have them piled up in the mold so it may be from sliding down. I'll try it a little hotter - 1450 sounds good. I've been fusing tempered glass for years, and never had any problems. Thanks for the advice, I'll let you know what happens. Beautiful pieces

[lorimendenhall]

good to know and what gorgeous pieces you made!!!!!

[Bert Weiss]

In general I try and keep my top temperatures as low as possible. When I started out working fusing broken tempered, my pieces tended to break easily. Eventually I got hotter and hotter until they maintained better integrity. This is a matter of heatwork which is different from kiln to kiln. If you make a piece and it breaks easily, go hotter, and or soak longer, next time. Once you get hot enough, there will be devitrification. The trick is to find the sweet spot.

The needling thing is caused when your dam is higher than the pile of glass. You can either use fiber paper cut narrowly or fiber rope to line the dam. The glass does not have a tendency to flow over it. It doesn't matter what is behind the front layer, except I would make sure there is kilnwash or paper there too, just in case.

[Peter McCarthy]

I fuse/slump tempered shards directly in a mold at 1450. I always get a few needles, and I just knock them off with a file. A small jeweler's file can get in between the shards .

[smallbitz]

I think that I may not be firing quite high enough. I'm trying a little hotter. I'll also give the little files a shot. Great idea. I have some small jewelers files that will work great!