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Old 07-13-2002, 05:29 PM
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Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
Join Date: Apr 2002
Location: Chocorua New Hampshire
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Re: Hmmmmmm. . .

Originally posted by F Thumb

I never thought of that. I tried a different cullet once (I forget which it was) and it was SOO SLOOOW to harden it drove me nuts.

Is longer working time normal for all batches?

I don't know of any commercial studio batch glasses that are "short". Eben has a point. At one time I made stemware ( I was young) and I wanted the stem to set really fast to keep the line clean. It flat wouldn't work with a slow potash glass I had worked up.
Normally a glass high in calcium is going to be really runny and set quickly. The down side is loss
of luster. You may want to stick with "what ain't broke don't need fixin.
as to Michaels questrion about offsets, sure, 50 grams of silica per hundred lbs would help bring the expansion back down, but I woudn't do it unless you are having problems with the C.O.E.. The trouble with pelletized batch is that things can't get inside the pellets so the mixing is uneven. It's not a big deal, more a minor nuisance.:
I am uncomfortable with melting at 2100F for any commercial clear currently out there.
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