Hi Ganoksin, I have a cast sterling silver piece that has some
traces of casting investment still in it. Perhaps I did not smooth
the wax sufficiently before sending it out to cast. Anyway, i can’t
get the stuff out of some of the smaller details without removing the
detail. I tried scrubbing with toothbrush, brass wire brush (removes
detail if i use it on my flexshaft, or doesn’t work if by hand).
Someone suggested using an ultrasound, so i ordered one. haven’t
tried it yet…
I never tried this, but a casting friend says that she has luck
removing traces of casting investment, by boiling the casting in a
vinegar/water solution. She said she did it in a pot on the stove,
not in an ultrasound. She did not tell me what proportion of vinegar
to water she uses. My concern would be that it would tarnish the
silver. Has anyone tried this process?
There’s a good chance that the investment is glued in place by flux
from casting - throw it in the pickle pot for awhile, then try
cleaning again. When we cast, we pick and scrub off the investment
down to the basic piece, put it in the pickle for 1/2 hour or so, and
then scub again. Ultrasonic will help, but we only use it at the
last, because a toothbrush is faster, and keeps investment out of the
ultrasonic tank, too.
Have you tried soaking the piece in water first than using a small
pick to loosen the investment and flushing with a small jet of water.
Perhaps if you have one a water pic. Just some thoughts.
I have been using white vinegar in a beaker or glass jar set in the
ultrasonic to clean off investment. Glass container in the
ultrasonic keeps the investment off the bottom of ultrasonic. Started
using the vinegar about 6 years ago when we ran out of divestor. I
tried different things to remove investment from textured castings
and the vinegar worked and did not cost much. Does not cause
oxidation. Last Spring we were out of vinegar and one of the students
tried Simple Green and water in the beaker. It works slowly. Either
vinegar or Simple Green/water breaks down and loosens the investment
and most of it comes off. Sometimes have to do a little scrubbing
with a brush to remove the last investment hold ons. Have not tried
just soaking the castings and not using the ultrasonic.
I recently read this tip on Charles Lewton Brain’s bench tricks CD -
and it has made a huge difference in cleanup time.
I soak my castings in vinegar - no water added. Sometimes I put a
small plastic container with the vinegar and casting to float in the
ultrasound for 10 minutes - this helps get the investment out of
tight spots.
I use a device I sourced from a friend who is a graphic artist. It
is a small hand held high pressure water gun that is used with
solvent to clean silk screens. It is made by a company called Tekmar,
model # TG 300. I just use water, and it will strip a casting to the
metal in seconds, no matter how much investment is stuck to it. It
even cleans Diamnate investment, which is very firm and adheres
strongly, like nothing. Takes the investment from behind the stones
that are cast in place as well. Greatest little gadget in the shop. I
had originally got it to spray the fuzzies off my wax models that
were milled. Works great for that too. They are a couple hundred
bucks…splendid investment for anyone who does lots of casting
or milling.
As this post has continued for some time, I thought I’d throw in 2
cents on the subject. Rio Grande carries a product, and I can’t
remember the name but it’s in their casting section. It is mixed in
water and used to soak castings. It dissolves investment quite
effectively, albeit a little slowly. One drawback, it develops mold
on the surface of the solution over time, so you can’t save it for
very long. Perhaps the Rio people will tell us if they still carry
it.
I pickle my casting tree (Silver or Gold) after quenching it in the
water, with 50 percent phosphoric acid ( 50% water plus 50%
phospharic acid) for 15 minutes, heat up to 45 degrees centigrade in
a Borocil beaker or a borocil bowl. all the oxid film is removed as
well as the investment soften downs which can be easily removed with
a tooth bursh or water jet pressure, efforlessely with no traces of
investment left. Always store the used phospharaic acid in a glass or
plastic container. Use it carefully even though it is not corrosive
as sulphuric acid to skin contact. Nuetralize the acid on the
castings with Baking soda solution prepared in clean water.
Use protective eye wear while using the acid, keep baking soda with
in reach to nuetralize the acid,in case of accidental spills. Put
acid in to water, while mixing it to make 50 percent strength.USE
THE ACID WITH CARE.
One can use the above acid at room temperature by soaking the
castings for an hour or can keep over night with out any damage to
the castings, whether silver or gold. Use copper tongs or plastic or
rubber coated tongs or brass tongs to place and remove the castings
from the acid.
I am using the above acid and method for softening the investment
and remove the oxide film from the casted tree, since last 15 years
sucessfully with out damage to the castings of gold and silver,
brass and copper castings can also be successfully cleaned with this
method and use of phosphoric acid as above.
Hope this helps.
May God bless all with total Health- Physical. Mental, spiritual and
Social.
Strive to be Happy
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Rio Grande carries a product, and I can't remember the name but
it's in their casting section. It is mixed in water and used to
soak castings. It dissolves investment quite effectively, albeit a
little slowly. One drawback, it develops mold on the surface of the
solution over time, so you can't save it for very long.
Thanks David,
Why yes, we do carry such a product, it is called “Freevest”, stock
702-288. It comes as a powder in a 5lb box (that’s a lot folks) and
costs $47.50. Check out the description on page 481 of the most
recent tools catalog.
I pickle my casting tree (Silver or Gold) after quenching it in the
water, with 50 percent phosphoric acid ( 50% water plus 50%
phospharic acid) for 15 minutes, heat up to 45 degrees centigrade in
Please, there is no need for dangerous acids to clean out gypsum
investment. Contact us for Gypsof Investment remover. This powder,
when mixed with water in your ultrasonic cleans all the residual
investment out by breaking down the gypsum bond. Your tree will come
out bright and clean because Gypsof also acts as a pickle. Gypsof is
not hazardous and a one pound jar makes gallons of solution.
Regards,
Bill Mull
Zero-D Products, Inc.
precision engineered materials solutions http://www.zerodproducts.com
Fax: 440-942-2130
Ph: 440-942-1150
800-382-3271 in USA, Canada and Mexico
Thanks all for the suggestions. So far nothing has worked. I tried
scrubbing, pressurized water gun, vinegar/boiling,
vinegar/boiling/ultrasound, pickle, heating using torch/then
pickling. So far, nothing. The model was fairly thin and detailed -
perhaps there was some porosity (?)
Anyway, I guess i will try some dissolving compound. If that doesn’t
work, I’ll have to after it with a brass wire wheel, but i do not
want to lose any detail.
A big hello to all you orchidians out there recently i got a textile
cleaning gun which i use for removing the investment from my flasks
which are containing small wires and ball and it use to create very
much tension for me before now I have been using that gun and it is
very much better from before I dont know from where you will get over
there but you can serach for textile cleaning gun which throws water
in the form of needle and it is very sharp check out and all the best
to you and regards to all the orchidians and big regards to Hanuman
good work on ganoksin