Re:Topic:Easy and cheap Ceramic shell casting: HOW?

Posted by John Dach on December 15, 1998 at 20:08:39:

Originally posted by John Dach on June 08, 1998 at 12:58:46:

In Reply to: Topic:Easy and cheap Ceramic shell casting : HOW ? posted by Daniel van Niekerk

Daniel,

Do you know if Ransom Randolf has a division in your country or close by? Or Remet or any of the other mfgrs. of investing material. I would start with looking for one. Dental investment or jewelry investment companies often sell other materials too. Question, why do you want to go the ceramic shell route for these small pieces? Have you considered, could you consider, using investment instead? Shell is great for larger (6" is about as small as I sprue up for ceramic shell unless I need a gob of the things but even then, investment is possibly easier to get going with in your case.

If you still want to go the shell route, great, I surely do not mean to throw cold water on your plans as I feel it is wonderful and use the shell process myself. The initial dip can be unfilled (the directions so stipulate) but I use filled (silica floured) ONLY for ALL dips, I just have to be careful about bubbles and I blow these off with compressed air. I use zircon for the first 2 sand coats then go to a 30 mesh fused silica for the balance. Final sealing dip (usually the 8th dip) is in the filled binder and no sand is added. The binder is coloidal silica, and each manufacturer has multiple formulations. R&R's Prinecoat/Fastcoat is a green/yellow, with serfactants, debubblizers, stabilizers and moisture indicator (help to know when interiors of pieces are or are not dry as it changes from a green to an orange when dry). You can apply the sands by sprinkling them on (I use a fluidized air bed for the 30 mesh fused silica applications but just sprinkle on the zircon (too heavy to easily float in a fluidized bed). You need a drying rack/shelves and a room that you can

maintain relatively constant temp and humidity (ideal not to vary any more than 3-4 deg. F while making the shells). A burnout oven is needed for either process as is a melting furnace. What ever

you need for the waxes you need it for either process also.

If you have problems locating shell material suppliers, look in the Thomases Register on the net.

Also try contacting any casting or foundry associations in your country and see if they have a listing of suppliers or could direct you to somebody.

Hope this is of help, and good luck!

John

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