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Does casting investment get old?


#1

Hi, I am wondering if casting investment gets old. I teach at a
community college and they have big drums of investment. I am not
sure how old they are. It seems that when I mix water and
investment, the mixture feels very thick, and I am not sure if it is
because the investment is old, if so, can Iadd more water ? If
anyone had a same experience, please let me know.

Thank you!!
Masumi Kataoka


#2

Use the powder to water ratio 38/100 40/100 42/100 happy casting


#3

I agree with mix. But I have always been told to remove the top 3
inches of investment it absorbs most of the moisture in the air


#4

On the other hand if it is properly closed airtight it can be used
without removing any. It always depends on how often you use the
investment.

It also depends on the kind of investment we are talking about.
Defer to instructions with what you have.

Best,

Russ
TJI, Inc.


#5

Last order picked up 2- 100lbs satincast 20 about 3 years ago from
Otto Frei. Have never ever done any thing other to mix up what I
need and never had any problem. I do keep container and bag closed.

Regards
Franz


#6

Investment is like a bag of cement.

Even though the ingredients all look the same they have different
specific gravities.

With time, a bag of cement will separate just sitting.

So will investment.

Investment should be mixed with a good dust mask and your hand.

Just reach into the bag and bring the bottom investment to the top.
I do this once or twice a month.

You can feel the material mix. You can also feel the consistency of
the powder.

In the old days (1970s) we used to flip the barrels upside done
every other month.

We usually bought ten barrels at a time and they would last us about
four months.

Old unmixed investment will not breath like new investment which
will cause a lot of problems.

Blow outs and porosity to name a few.

Spin and vacuum casting since 1971.

Kind regards,
Todd Hawkinson


#7

Hi,

Just use powder & water in 100:40 ratio time of investment may
reduce from 7 minutes to 5 minutes be quick in carrying out
investment.

Cheers
Umesh