Page 180 - Casting of Angels- Dave Parvin

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Making a Vacuum

Chamber

by David E. Parvin, A.L.I.

n the last issue of Sculpture Journal, I discussed I went to a restaurant supply store. I was told that larger
the advantages for using a vacuum or pressure pressure cookers are getting hard to find because too many of
chamber or both to achieve castings that are them blew up and nobody wants the liability of selling them.
bubble free and with better detail. But in order to Since we are talking about creating a vacuum, the much more
reap the advantages, one has to have the equipment. In this genteel imploding possibility doesn't seem real dangerous.
issue, I will explain how to construct economically a very But, I guess, nobody wants to bet the company's future by
functional vacuum chamber. In next month's issue, I will do making a vacuum cooker ... The good news is that there is a
the same for a pressure vessel. The month after that, I will put tremendous selection of professional stock pots available in
it all together and describe how to achieve results that would both aluminum and stainless steel. They go from way too
be impossible otherwise. small to large enough for two full grown people to climb into
All that is needed are some sort of a container, a few (not that they would want to). An aluminum one about 12 x
fittings and connectors, some pressure hose, and a vacuum 12 inches is about $50.00; stainless steel is about three times
source. Once you have the components, except for the time it as much and no better for our purpose.
takes for the rubber seal to cure, the assembly takes just a few To complete the pressure chamber, you only need a
minutes and costs as little as $200.00. This article is not strong, transparent lid that has been drilled and tapped in
meant to be a blueprint but does provide enough information three places and has an air-tight seal. The lid should be 1 inch
to allow almost anyone to make a functioning system. I thick Plexiglas about two inches wider then your pot. (The
suspect that most of you who may live in remote areas with first lid I tried was only 1/2 inch thick and noticeably bowed in
limited access, I have proved phone numbers and/or e-mails under vacuum. I suspected that it would have eventually
to make your acquisition less frustrating. failed). As you can see in the photograph, the three
attachments to the lid are the hose to the vacuum source, a
vacuum gauge, and a pressure release valve. Notice that the
attachments are on the outside of the lid just inside of the rim
of the pot and about 120 degree apart. Holes drilled near the
outside are less likely to weaken the lid than if more to the
center. The hose, gauge, and release valve are probably
available at your nearest Ace Hardware, Home Depot,
Lowes, etc. for about $10.00, $8.00 and $2.50 respectively.

The author's home-assembled vacuum chamber
There are several possibilities for a container. The one
pictured is simply a pressure cooker about 12 x 12 inches
minus the lid. Since I have had this for at least 10 years, it
seemed only appropriate that I check current prices. I went to
my closest Target store and to my surprise, the only pressure
cooker available was much smaller, too small. So I tried
Sears, ditto. The same at Wal-Mart. However, Wal-Mart has The amazing Air Vacuum Pump
a 16 quart stainless stock pot for $34.95 that looks as if it
would do just fine. Sears had a similar one only the price was
about $10 more. Then I hit the mother load.
Sculpture Journal – September 2003 www.artcastingjournal.com