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Old Investment

Hello all - Has anyone had any bad experiences using old investment?
I have a large coffee can full of investment (in a zip lock bag)
packed away in my closet in the house, which is about 7 years old. I
used it in my Jewelry class and now I’ve purchased a used Kiln and
would like to start casting again. Would anyone know if that is
still good or should I throw it? Thanks for your help.

I usually wouldn’t take the chance with old investment. but if the
items you’re going to cast aren’t very important, and you are sure the
investment has been tightly closed away from humidity, you can first
shake and mix well your investment in its own bag or box. this will
allow all its microscopic components to remix after they have been
separated and settled from being unmoved for so many years.

Fady Sawaya
3D jewelry designer

I’ve sucessfully used “vintage” investment. Are there any noticable
gritty hard lumps? If not, test a small amount to see if it sets up
(hardens) normally, and if so it will probably be ok. But if all you
have is a coffee can full, why not get some new investment, and use up
the old stuff a little bit at a time with the newer material. You
might also reserve the older investment for those special cases where
you have to do investment soldering (holding small items in alignment
while soldering).
Alan Heugh

I couldn’t say whether the 7 yr. old investment will produce a good
pattern or not, but with investment being approx $.50/lb (.03/oz),
why subject something you have spent time creating to such an unknown
variable with such a large percentage of failure? My opinion, toss
it - or cast something that isn’t too terribly important just to see
what happens for future reference. And, of course, let us all know
how it turns out.

On a related subject, does anyone have any creative ideas about what
to do with used investment? Could this stuff be good for the lawn?
I go through only about 250 pounds of this stuff a year, and, having
a bit of pack rat blood, tossing anything that may have an
alternative use goes against the grain.