Re: Pressure tank wanted

From: Kirk Alcond (
Date: Fri Apr 18 2003 - 01:23:18 EEST

Hi Scott,

I have had better luck with the reverse approach. Instead of forcing the
material into the mold suck the air out of the mold and the pour material
will fill the empty space. First, you put your pour material into an
oversize container and place it in a vacuum chamber. Draw a vacuum on it to
off-gas or foam-off all the unwanted bubble forming gas. Then you place
your RTV mold in the chamber, pour in the cleaned pour material and draw a
vacuum on it. Any air in the mold will be vacuumed out and you will have a
perfect casting. You don't need a super high powered vacuum chamber to do
this. You could make your own using an old refrigerator and an old air
compressor pump hooked up in reverse. After testing it to make sure it
works, install a 1/2" thick lexan window and lights so you can watch the
foaming process. For experiments you can use a bell jar over a small vacuum
former table. This is just a suggestion, but I have had great results with it.

Have a "Creative" day!
z Kirk
Kirk Alcond, UCLA Architecture, Shop Supervisor,
Phone: 310-825-1626

At 03:34 PM 4/16/2003 -0500, you wrote:
>I'm interested in buying a used, 30 gallon(ish) pressure tank for the
>purposes of pressurizing RTV molds. I'm having a heck of a time locating
>any. If anyone has any leads, please let me know.
>Scott Moeller
>Progressive Engineering, Inc.
>7741 Commercial Lane
>Allenton, WI 53002
>Phone: 262-629-4610 x35
>Toll-free: 866-629-4610
>Fax: 262-629-4625
>E-mail: <>
>web: <>

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