Re: CASTING Plaster Investments vs. Ceramic Shell?????


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Posted by Robert Oblon on January 16, 1999 at 17:17:56:

In Reply to: CASTING Plaster Investments vs. Ceramic Shell????? posted by bruce paul fink on January 15, 1999 at 16:48:15:

Well I guess I have to put my 2 cents into into thjis deal.

I've been in the foundry business for close to 30 years..Ouch!

I was trained using solid investment and we did some very large castings in one pour. Part of the fun with solid investment came from the dirty process of putting on the face coat and then pouring in, sometimes, several hundred gallons of investment and then building a kiln arount the investment or craning the molds over to a pit kiln that had been built next to the furnaces...

Once I started using ceramic shell as the casting medium I was very pleased as to the increase of fine detail that was present. Alot of my early work was very high polish and found that the shell molds, when built properly, allowed me to have tighter polishing surfaces. Of coarse as the process progressed I realized the importance of using as much new ingot as possible and minimun scrap. Once I used the shell process enough I felt that it was easier to work with then solid investment.

I feel that both mediums have there good and bad points. We have cast some very large shells weighing upwards of 200# in bronze. For larger castings, we cut up the wax pattern and then re-assemble via Tig welding with minimum problems. I feel that one has to develop a style for either method of casting.

As for cleanup...I use a core knock-out machine, used in sand casting, to knock the shell off of the castings and then sand blast the castings with either "garnet" if the surface has texture or "glass beads" for finer surfaces...

The bottom line is whichever works best for ones setup and background .

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