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RTV mold deterioration

I have made RTV molds of finely-detailed pieces (closed filigree).
To eliminate air-bubbles during injection, I pre-paint the receiving
surface with hot wax. However, the surface of the mold starts to
degrade very rapidly and only a few usable waxes are produced. The
waxes get increasingly ‘furry’, indicating micro-tearing of the
surface of the mold. Possibly the painting is causing the wax to
adhere too closely to the surface. Could anyone suggest a product
that could deal with this problem? (I have been using Dow Corning HS
11 ). Thank you. Brent Glasson

Hi, Brent–It appears you have two things going on here. Before I go
into mold deterioration, I suggest you look into why you are getting
bubbles in your wax in the first place. You can call me on this, as
it cannot be answered without knowing a lot more about what you are

The product you are using, Dow Corning HS II is an extremely soft 16
to 20 Shor A durometer material. This may be working against you.
The mold surface should not break down, as all silicones will
withstand 500F continuous. The tear strength of the product is 125
ppli, which is substantial. The only thing that comes to mind is
that you may not have enough mold body backing the pattern. Again,
give me a call and perhaps I can sort this out with you.


Bill Mull

Zero-D Products, Inc.
38285 North Lane. #103
Willoughby, OH 44094 USA
fax 440 942 2130