Lead Crystal

[pshash]

So I broke one of my mother's beautiful lead crystal bowls and would like to do something with the glass. Can anyone recommend any references for firing, slumping schedules and annealing? I have been told the glass is soft and all lead crystal is different. I would appreciate any recommendations anyone has. There is no ID on the glass as to where it was made.

[Bert Weiss]

Stone gives schedules he notes as "lead" Your glass is most likely either 20% lead, 40% or a bit more. He does get more precise on one page, noting anneal temps for various sources, but you can catch them all with an appropriate ramp speed. This is a good excuse to get the book. Brad sells it. Lead glasses soften at lower temps than the glasses you are used to. So pay attention. There is plenty written about casting with Lenox (lower lead content) or Gaffer (higher lead content).

[pshash]

Thank you.

[Morganica]

Actually, your lead crystal bowl can be anywhere from 1-48% lead (oxide), depending on when and where it was made. Today in the US, "lead crystal" is legally any glass containing 24% or more lead, and anything 30% or more is generally called "fine lead crystal." But a manufacturer can call something a lead glass or leaded glass even if it only has 1% lead (if it came from Europe it must be at least 10% lead).

So it's hard to say how much different it will be from a fusing glass (or float glass) without knowing more about who made it and when--if you've got a sticker somewhere on the bowl (or an engraved mark) it'll be easier to find out. The more lead it has, the "softer" and more devit-resistant it will be.

One way to get a ballpark idea is to compare the weight of that bowl to a glass bowl of comparable size--the heavier it is, usually, the more lead it contains.

Overall, though, the same rules apply as for any mystery glass--don't mix it with anything else, do a test piece first to get an idea of the schedule. Since it's lead, I'd start by assuming that the processing part of the schedule should be maybe 25-40 degrees cooler than the typical fusing schedule. Then I'd adjust from there. Leaded glasses are usually pretty forgiving and they can make some pretty stuff.

The alternative, BTW, is to consider cutting up the bowl and use minor slumping or coldworking to turn it into jewelry, especially if it's been cut/faceted. Lately I've been seeing a lot of old lead crystal cut and polished into pendants and brooches, and some of it is really beautiful. And a friend incorporates cherished-but-busted dishes and drinkware into kitchen mosaics, and incorporates clippings, recipes and other family documents into the walls behind clear glass shards--the results are really stunning. Something like that might be a nice way to use the bowl, too.

[pshash]

It is very heavy compared to any other glass bowls so I assume it has quite a bit of lead. I used a firing schedule found online and it didn't fuse at 1350. I have it in the kiln now and am fusing at 1450 to see what happens. Yes, I did smash the glass. I will let you know what happens but thanks for the info.