Hi Gus, Large shops generally use a water blast cabinet to blast the
investment off after the flask has cooled. You can make your own with
a pressure washer and some kind of waterproof box. I made one that
looks like an incubator with gloves and a glass window. I used a large
nalgene plastic tank and a pressure washer from Grainger. If you have
a small shop you won’t need to get that fancy. Home depot has some
reasonably priced small units that should do the job nicely.
John,J.A.Henkel Co., Inc.,Moldmaking,Casting & Finishing