Raku has generally been stable for me. Some other colors, not so much. I've had cracks show up >6 mo. I suspect lead content may play a role. Higher annealing helped, but I ended up getting a small quantity of rods in "96" to avoid the headache.
I've seen others post better results, and if you think about it, bullseye at 90 should be pretty good with the furnace glass, which I've seen listed more at 91-93 COE. But the viscosity plays a role too.
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Lynda
Cheetah, 5 lpm and 7lpm conc/generator (8-9 psi), natural gas (booster), started 11/06
"The time you enjoy wasting is not wasted time." -- Bertrand Russell
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