Natural Stone Cabs and ACS using plaster forms

[longliz1888]

I am not quite sure how to word this but here goes.
I bought several oddly shaped Natural stones such as agate to name one of them and also some opals.  I am not good at silver bezel settings and think I read someplace that I could take casts of the stones and use them in place in position on the clay when firing.  I will be doing prong settings or another technique to finish them once the clay has been fired.
Is this possible to do using the plaster cast I have made?  I know once it is fired there may be some shrinkage but am hoping that the plaster will prevent this somewhat but I will make allowances for it anyway.
I thought I read this in Tim McCreight's book but at the moment I can't find the book.
Any help or advice that anyone can offer would be greatly appreciated.

Thank You

longliz1888

[Metalman]

I love odd shapes. I have a couple of methods for dealing with them.
1] If there is a 'base' or 'flat side' which makes sense in your design to be the attachment 'side' draw an outline of that face. then use a copy machine and enlarge your sketch 9% - this will account for the main portion of the shrinkage - you can build to your copy and off you go  [there will be some fine tuning to this method, usually you can grind/file to fit after you finish firing]

2] I sometimes take the stone/object  and wrap it in layers of masking tape. I think I usually use 3 layers [but this is dependent on your masking tape; the 'cleanness' of your wrap, etc.] What we are doing here is physically expanding your stone  [about 8 -10%] so you can build to the piece, then take it out of the Art Clay and fire.

About the plaster:  I think this could work -  I have not seen the book you refer to. I am concerned about the plaster in the kiln.  Needs to be dead dry as the moisture can cause problems when firing. Also - plaster breaks down under heat - this could be a problem - you may just have to experiment and try to make it work

Please let me know if this helps or when you learn more - I like the technique idea although accurate molds of stones may or may not be an easy thing to do. At jewelry scale [small] there are materials issues and inaccuracy will be a big problem. Have fun testing it all out.
K