Thread: cullet shortage
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Old 03-17-2018, 05:09 PM
Pete VanderLaan's Avatar
Pete VanderLaan Pete VanderLaan is offline
The Old Gaffer
 
Join Date: Apr 2002
Location: Chocorua New Hampshire
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Pete VanderLaan is on a distinguished road
I spend an inordinate amount of time on this issue being one of the relatively few who make glass bodies from raw stuff and also selling crucibles. If I didn't do that, I would have had to find another way to make a living long ago.

If you run electric without a flue, you're going to see the assault. The borate as Durk so kindly identified will eat a lot of stuff quickly, Boron above 2% will do it as will Barium above 2-3 percent. This glass has both.

We strive to make a decent crucible at a fair price, Glass is still the universal solvent. The low melt glasses do it for a reason. Melt them hot and they'll clean you out. I would say now that these glasses SHOULD eat our pots and I expect issues. I advise my clients now to sinter their pots on receipt at 2500F. Fred Metz goes to 2650F.
I just don't melt these cullets. I do melt occasional fluorines and I do that at under 2200F in under three hours. They eat pots, brick , crowns, neighbors, thermocouple tubes, you name it. Boron is just another low melt material. Fluorspar is another. I use nitrates to get there. They have the most benign effect on the pots.
It is not a falling off a log to dump the boron from the German stuff. It will change the viscosity, annealing, expansion ranges along with a host of other issues. It can be done.
Jordan, I actually can't quite tell what the second shot is of but it's gross. Part of the problem here is our national choice of refractories and how they get used. It's mostly alumina and it would be far better if it was fusion cast but you would spend weeks bringing the furnace to temperature and there's no patience for it. Slippery Rock is the only bunch doing AZS in this country anymore. Eddie locked on to it but if I hear you right, it's under assault by the German cullet.

If Oceanside had a brain in their heads, they'd be in Tijuana right now making the purloined SP87 formula they bought from SPectrum. I'd invest tomorrow.
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