Back to Ganoksin | FAQ | Contact

Casting stones in wax


#1

Hi gang,

I have been tinkering with casting diamonds and other heat
tolerant stones in wax for a while now and having good success and
saving tons of time channel setting. Although, I have a couple of
questions for those of you who may do it on a regular basis. I am
using the long, low temp burnout cycle and using vacuum to cast.
The max temp I have gone up to is 1100F. The castings come out
rather dirty compared to conventional castings due to the lower
burnout temp. Thankfully, I have a magnetic pin tumbler to aid in
the finishing process. I don’t think I would cast with stones
without one. I haven’t had a big problem with shrinkage porosity,
but I have learned (for me) it is better to sprue on a button
rather than a tree. I seem to get some incomplete castings when
sprued on a tree. Could this be overcome by centrifugal casting
rather than vacuum? (I would like to get more than three or four
models in a flask) Would the turblence exerted by the centrifuge
cause the stones to break loose from the investment?

I am adding 5% boric acid to the investment mixture and it seems
to be crystallizing somewhat excessively. I have heard that by
adding boric acid to the investment, one can safely go up to 1250F,
but I havent had the guts to try it yet.

Has anyone successfully gone to this temp? Any advise or help would
be appreciated.

Ken Sanders,
Waco, TX

P.S. Alan Revere, if your reading this,I love your book, but where
in the world do you find the large round edge joint files at? I
can’t seem to locate them.


#2
   but I have learned (for me) it is better to sprue on a button
rather than a tree. I seem to get some incomplete castings when
sprued on a tree.

i would think a thicker tree that would stay hotter to feed the
shrinking model would help. i kinda always thought vacuum was
better than centrifugal casting but that was by teaching not
experience. Robb.


#3

Ken,

I have succesfully cast diamond in 14 karat gold using the 5%
boric acid and a regular 1350 degree burnout cycle. The Boric acid
coats the stones and protects them . Try it on a test model with
some old chipped mellee or whatever you have available. I think
you will find it works great and the cleaner burnout will save you
clean up time. i don’t do this regularly but have experimented
enough to be confident casting clients stones in custom pieces.
You can E-mail me on or off orchid if I can be of any assistance.

Good Luck
Ray


#4
I have been tinkering with casting diamonds and other heat
tolerant stones in wax for a while now and having good success and

Hello Ken:

I found your letter very interesting as I had no idea that casting
w/stones mounted in wax was even possible w/o burning the stones.
I know there is equipment (somewhat expensive) which can accomplish
this safely by eliminating oxygen at the time of injection. I would
appreciate hearing more on this subject as I am currently working
with a retailer who wishes to make a line of pieces using this
method.

Many thanks;

Steve Klepinger


#5

Hi Ray, Could you explain what 5% boric acid means? Is it 5% by
weight of the plaster ? I appreciate it. Tom Arnold


#6

I have been told that poor quality amethysts are often heat
treated and sold as citrine. If you cast an amethyst in wax would
you end up with a yellow stone?

Just curious,

Lisa


#7

Dear Lisa, I think you might just end up with some cracked quartz!
I’ve not known either amethyst or citrine varieties of quartz to
survive the sort of heating you’d get in casting without cracking.


#8

Lisa, I think some amethyst will turn yellow at 480 deg. F., too
low for a good burn-out. Normal burn-out temp. would shatter the
stone. Tom Arnold