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Investment


#1

Has anyone heard of reusing investment? I was talking to a
sculptor, and in the conversation the subject of used investment
came up. He told me at the school where he was trained, the
instructor reccommended using used investment as a “filler” in
his casting rings. The used investment would be mixed with fresh
on a 50 / 50 basis. Says he does this all the time with no
problems. I have been doing jewelry for over 25 years, and all
the books I have read have never mentioned using used investment.
Anyone else heard of this? I will probably give it a try on
some things I have molds of just to see if it works. I realize
investment is not a terribly costly part of the process, but
filling a ring for a small item does seem to be a bit of a waste,
and waste is waste.


#2

Aufin : I think maybe the health risks involved with refining the
used investment back into a smooth powder to mix with new, far out
weighs the savings. Please wear a good breathing mask. Michael
Mathews Victoria,Texas USA


#3

When you buy investment it comes with a binder and a particular
grain distribution to give it the properties that are required for
a mold. When you cast, you use up the binder and when you quench
and clean the molds, you lose the grain distribution. I don’t see
any way in which you could come close to the required properties
using half the bond and poor grain distribution.

When I was making industrial investment castings, we would dip the
pattern tree in a fine slurry for the details and finish and,
after drying, invest the trees with a coarser material to which we
also added the binder. Perhaps in this way you could reuse the
investment but we used to throw it away.

Lee


#4

I think this reuse is more common when casting large items where a
can could contain 3000+ lbs of material. Even when the material is
free, in quantities like this getting rid of the stuff becomes a
major problem. It is done often by investment casters with little
or no problems.

John and Cynthia/MidLife Crisis Enterprises
Maiden Metals/C. T. Designs/ Bloomin’ Wax Works. etc.

PO Bx 44, Philo
CA 95466
Ph 707-895-2635 FAX 707-895-9332

The playfulness of the Universe
is reflected in the dance of the stars!


#5

I have a question for those considering reusing investment. We
remove our investment with a water pistol and collect it under the
"sink" and before I just dropped my flasks in a 5 gal bucket of
water and the investment settles and is technically reusable if you
dry it out, but it has oxides, sulphides, and John Burgess only
knows what else and smells of rotten eggs (hydrogen sulphide?) and
can get very odoriferious…I dont want to reuse this anyway. I
can see it if one were casting large pieces as was discussed after
dipping in fresh investment or painting on or in a casting house
situation. Is it worth the trouble @ $.40/lb?


#6

The problem may have been from breathing the steam that quenching
produces - many people do not realize that the steam can carry
particulates that could pose a problem - when quenching a flask, one
should immerse it quickly and immediately and leave it entirely
under water until the “churning” of the steam completely stops.

Hope this helps,
linda Weiss
www.lindaweiss.com


#7
 The problem may have been from breathing the steam that quenching
produces - many people do not realize that the steam can carry
particulates that could pose a problem - when quenching a flask,
one should immerse it quickly and immediately and leave it entirely
under water until the "churning" of the steam completely stops
Linda, 
There have been tests run that show even with holding it under

water the bubbles that come up to the surface release the sub micron
particles that are so dangerous. Unless you have the quench bucket
vented properly you are asking for silicosis and possibly lung
cancer. It is much safer to wait till the investment cools and then
break out the casting with a water jet.

Jim


#8

Linda, You bring up a good point. I suggest holding the flask for a
while until the button has lost its reddness before quenching or
even a bit longer…the metal is still contracting and pulling metal
from the button anyway. The investment will break down even if just
warm. Then, as Linda says, thrust it into the water (doesn’t have to
be cold…just cool), and keep it completely under water until it
stops gurggling. I find this creates a very small amount (if any)
steam and minimizes the possibility of particles wafting up. I also
wear a full plastic face mask and that keeps the steam from hitting
me in the face and breathing it in.

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut1


#9

Hello All: Because I cast at the end of my work day, I almost always
wait at least an hour or overnight before I remove my castings from
the flask. I put the cooled flask in a bucket of water and let it
soak for a minute. Then I push the investment out of the flask with
my thumb like it was a “push pop” ice cream. I take the pushed out
investment and crumble it off the casting into the bucket of water
and then scrub the casting with water and a tooth brush. Then I
ultrasonic it in a de-vesting solution for a while. I mainly use
2.5X3" flasks and cast single custom items so people using larger
flasks would have to wait longer than 1 hour. As far as I know there
is no advantage to the casting to quench it right after it is cast. I
am not sure what that does to the grain structure of the metal if
anything. I think in many cases, the anticipation to see and begin
work on the new casting overwhelms and causes us to hurry the
process. Michael R. Mathews Sr.


#10
As far as I know there is no advantage to the casting to quench it
right after it is cast. I am not sure what that does to the grain
structure of the metal if anything. I think in many cases, the
anticipation to see and begin work on the new casting overwhelms
and causes us to hurry the process. Michael R. Mathews Sr. 

I quench soon after I cast. A few years ago I tried waiting 15
minutes to quench but when I went to pound up in size a few silver
rings I’d cast (using Rio Grande antifirescale casting grain) I had
some cracks appear like they were brittle. So I assume that quenching
soon after anneals the metal. I could/should have annealed before I
tried to size them but why take the extra step if I can just quench
while the metal is still hot to achieve this?

Annette


#11

Hello All ,

Because I cast at the end of my work day, I almost always wait at
least an hour or overnight before I remove my castings from the
flask. " 

While you can do [ or get away with ] alot with your metals , there
are suggested Temps for quenching cast metals , my understanding is
that these suggested or prefered temps are the same as the quench
temps that you would use after annealing . Quenching at “black heat”
[ when the metal no longer glows when observed in a dark place , or
about 800 - 900 degrees F.] would be the general rule , Some
exceptions ; DE-OX golds , MAY need full air cooling , check with
your supplier , RED golds esp 18K should be quenched from RED heat .
the Peach alloys , also from RED heat . Contrary to much info on
White Golds they should NOT be air cooled but quenched from black
heat . Mark Clodius