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Bubbles on castings


#1

Dave Stephens writes:

MG, damnit forgot your real name, do you use any sort of debubblizer on
your waxes before you invest? I’ve been using denatured alcohol and still
get bubbles in the crevices, been thinking about painting on investment
in
those areas to avoid that…Dave

Dave:

I use denatured alcohol mixed with debubblizer. I make sure there is plenty
of time for the alcohol to evaporate before I invest. Debubblizer used
straight leaves a kind of gummy film on the waxes.

Another thing I do is to use hot tap water for the investment mix. I know
this goes against the books but it still works. Make sure you time your mix
as this causes it to truly start to set up in 10 minutes. By using hot
water the investment boils more violently under vacuum and helps to remove
more of the bubbles.

I used to go to great and painful measures to make sure my investment water
was 70 degrees F. I have been told that hot water actually strengthens the
investment also. Go figure.

I had to see it to believe it.

Kenneth Gastineau
gastin@mis.net