Probably not good for fusing…

[katkramer]

Are you planning on fusing them, or creating cold mosaics with the broken pieces?

Moretti is another “soft” glass that expands and contracts more than Bullseye or System 96.  Different types of glass have different coefficients of expansion…Bullseye is 90COE, System 96 is 96COE, Moretti is 104COE, and Pyrex/Boro is 32COE.  The larger the number, the more it expands and contracts when heated.  But if you’re using it without fusing it…just breaking it and putting it in a mosaic, then these numbers are irrelevant.

If you have access to a kiln, you could cut pieces, take them up to a full fuse temperature (1475°F should work fine, hold for 5 minutes), and they will make nice rounded nuggets for mosaics.  As long as you’re fusing the rods with other Moretti rods, you shouldn’t have a problem.  For example, you could arrange them in a tic-tac-toe board design, and fuse them, and it would work.  It would NOT work if you did the same thing with a couple of Moretti rods and a couple of Bullseye rods.

If you try to fuse it with other glass of unknown COE, they may fuse together, and look fine, but because of the internal stresses in the glass from the competing COEs, it will eventually break.

Or you could take up lampworking!

: )
Kat
http://www.katkramer.com