Metal Casting Zone

Hi, I'm new to this forum and fairly new to bronze casting. I work at a fine art foundry and am training in the entire process. We do about 40 to 60 cups a week and I am learning quickly, so hopefully in the near future I will be able to contribute a great deal to this site! Our foundry has minor problems with shells cracking during the flashing process. Opinions vary on how serious an issue this is and we seal the cracks with Sairset, but I wonder if there is a way to remedy the problem. Maybe an Autoclave or additive in the investment process. Also I've heard a wide variety of temperature patterns in dewaxing. If you had success in this area I would appreciate any insight. Thanks!