Back to Ganoksin | FAQ | Contact

Disposing of investment sludge

(Why does it seem that almost all my questions are about how to get
rid of things? )

I’ve got a 5 gallon pail half full of investment sludge left over
from de-investing casting flasks. I set this pail out in our garage
for three months, hoping the water would evaporate, and leave me
with a bucket full of plaster I could knock loose and dump out. The
water never evaporated completely. How do I dispose of this gunk?

–Kathy Johnson
Feathered Gems Jewelry

Hi, If you are casting gold, don’t be too quick to throw that
’sludge’ out! There is more gold than you think in the investment.
In any case, you can spread it out on an old piece of canvas and let
it air dry. If it is gold casting investment, you can save it and
send it in with your next bench and floor sweeps shipment to your
refiner. I don’t know if jewelry refiners will accept it, but I know
for a fact that Ney/Degussa in Hartford Xonnecticut will gladly
accept it. I have been dealing with them for over 30 years now and
have never had a complaint. My Rep even ships it for me at his


Kathy, Pour the water off the top of the plaster, then stick a thick
roll of newspaper into the plaster. The newsprint will work like a
wick to draw remaining water out of the investment, leaving it
semi-solid. If you remove the roll of newspaper and let it dry
another day of two, you can knock it all out of the bucket and easily
dispose of it. I use heavy 3 mil contractor trash bags to dispose of
the semi-solid investment from there.

Mark Moretti
Fredericksburg, VA