# Vacuum or Pressure Pot?



## Rockytime (Jul 30, 2014)

I just need a simple answer as I know nothing about this HF business. Am I getting this correctly? Vacuum is used to withdraw air from wood so that the wood will absorb a solution to stabilize it and pressure is used for casting plastic blanks so that bubbles do not form. Also is the same HF pot used for both pressure and vacuum? Geez, so much to learn but it's fun. More opportunity to spend more money which I don't have. :>)


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## frank123 (Jul 30, 2014)

A pressure pot can be used for vacuum but it will not allow you to observe the bubbling of the air out of the wood so it is usually a bit easier to use some kind of transparent vacuum chamber rather than a pressure pot.


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## lorbay (Jul 30, 2014)

I use a 3/4" acrylic lid on my pressure pot when I am doing vacuum. 
Lin


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## Cmiles1985 (Jul 30, 2014)

Answer to your first question is: yes. Vacuum is used to pull the air out of the dry wood so that resin fills the voids in the fibers. Pressure is used to reduce the size of the bubbles in the resin so that they are not visible. The mentioned HF pot can be built for both pressure and vacuum. I love the idea mentioned above about a transparent lid...I just have a different connection for vacuum on my lid.


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## Jim Burr (Jul 30, 2014)

http://www.penturners.org/forum/f43/casting-help-please-pressure-vacumm-121522/
http://www.penturners.org/forum/f178/pressure-vacumn-pots-123171/
http://www.penturners.org/forum/f43/vacuum-pressure-systems-123812/
http://www.penturners.org/forum/f178/vacuum-vs-pressure-121979/
http://www.penturners.org/forum/f43/i-need-clear-advice-blank-making-120384/

And dozens more...


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## Rockytime (Jul 30, 2014)

Jim Burr said:


> http://www.penturners.org/forum/f43/casting-help-please-pressure-vacumm-121522/
> http://www.penturners.org/forum/f178/pressure-vacumn-pots-123171/
> http://www.penturners.org/forum/f43/vacuum-pressure-systems-123812/
> http://www.penturners.org/forum/f178/vacuum-vs-pressure-121979/
> ...



Thanks Jim, I should try using the search engine. I have read almost everything in the library, some things more than once. But never thought of the search engine.

Much thanks for your effort.


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## steve worcester (Aug 2, 2014)

lorbay said:


> I use a 3/4" acrylic lid on my pressure pot when I am doing vacuum.
> Lin



Me too. Got a chunk of scrap polycarbonate out of the bin at the plastic house, put it on a screw chuck on the lathe and spun the outside to size. The I cut a groove for a gasket and took it off the lathe and poured a 30 shore D rubber into it to make a gasket. Drilled and tapped the center to take a pipe fitting for the hose. Works fine.
 Under vacuum with Cactus juice you will get crazing from the juice degrading the plastic, but it only affects the visual not the performance.


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