Don, there are two factors to consider. First the viscosity of the
resin, which is probably published on the label. Second, it is a good
idea to think in terms of a vacuum pump capable of 27 inches Hg and
more. I don’t know what can be achieved with a hand pump.
Here is some of what we have learned in making and selling high
strength Silicone RTV mold rubbers. Many, many jewelers do not have
vacuum pumps that dependably achieve 29 inches Hg. There are many
reasons, not limited to improper care and maintenance and home built
systems that have not been well constructed. They just don’t pull
enough vacuum for the typical high viscosity of most high strength
silicone RTVs, which tend to have viscosity levels as high as 1000
We recently introduced our LOVIS silicone RTVs, which have viscosity
of only 200 poise. The folks who did not have success with silicones
are now de-airing comfortably at 27 inches.
If the resins you wish to de-air are 200 poise and lower, you will
be OK at around 27 inches, but you will have to find out what the
hand pump is capable of doing first.
Finally, I can’t think of any situation where it is good practice to
do your work in a half-butted manner. Go for the dependable vacuum
pump and forget the hand job. You will have far wider capabilities
and less to worry about.
Zero-D Products, Inc.
precision engineered materials solutions