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Finishing rock cast fine silver


#1

I cast a small rock with carved design in fine silver. The rock is
slightly grainy and the carving is fragile. My inclination is to
just remove the sprue, do an acid finish with a litlle highlighting.
But this is my first experience with fine silver and rocks. I am
wondering if I should give it a magnetic tumble… or something else
I don’t even know about. Other craftspeople do most of the steps of
my designs, but I need to tell them what
it is I want done. Any suggestions?


#2

How do you cast a rock? Does it burn out?


#3

Grammar Alert!!! What I meant to say was: I made a silicon mold
from a rock, then I had a piece cast in fine silver. Thanks for
understanding, Rebeca


#4

Hello Rock casting person, If you remove the sprue, emery that spot,
sandblast the entire thing and then go over it lightly with 4/0 steel
wool, you will have a great looking rock! Have fun. Tom Arnold


#5

Sorry, things like that do not burn out, etc… no bone or rock,
the calcium in the bone is a problem, and the silica in the rock
cause it not to burn out sorry… AW


#6

I had the rock cast into a silcon mold. The shrinkage is about 5 to
6% less than a rubber mold, but the molds don’t hold up as well.
They sort of get sticky and melty after a while unless you store them
in a metal cabinet or container. You can cast just about any object
and still retain your object. I prefer rubber molds but the silicon
molds can be alot of fun and also work well for tiny pieces due to so much less shrinkage.

Rebeca


#7
 How do you cast a rock?  Does it burn out? 

:slight_smile:

I guess she cast it with Delft clay, or praps cuttlefish.

If it was me that cast a carved rock in fine sil I’c cut the sprue
off (I assume it’s quite a hefty sprue for such a volume) and either
file it straight and polish it so it’s kind of obvious what it was, or
try to disguise it by copying the same ‘rock’ texture. A burr right on
that one place might do this better and quicker than tumbling, which
would affect the rest of the stone. Do a random pattern with a big
ball burr. Use a coarse burr: fine silver’s softer than 925 so it
might clog up a fine burr.

Or how about this: cast a second one, take a piece from that and use
it as a plug on the first casting where the sprue was. Fancy.

Brian
B r i a n � A d a m
http://www.adam.co.nz/workshops/usa2000/