Welcome to Orchid, John. There are good articles on stone in
place casting in the last 2 years of the Proceedings of the Santa
Fe Symposium on Jewelry Manufacturing Technology…available from
Rio. AJM has also had a couple good articles. I’ve been adding 2%
by weight of the investment powder weight of Boric Acid,
dissolved in the investment water and having good results with
cheap diamonds, rubies and sapphires, using my normal burnout to
1350 F. The investment slurry sets up about 2 minutes faster than
normal, ie 8 minutes max of working time. The fired investment is
much harder than normal investment, so it’s a little harder to
breakout. Good Luck Chuck Hunner