Shrinking your pressure pot?

[jeporter02]

Has anyone found a hack for reducing the available air space inside your pressure pot? Here's the problem: I cannot get a compressor for a variety of reasons, so I'm left to fill my pot with a tire inflator. It works fine, except that it takes about 4.5 minutes to get to pressure. Even with a 12 minute open time if I use Alumilite Slow, that doesn't leave me much time to mix, pour, and get it set in the pot. I tried filling the pot with water, and setting my casting on a floating shelf of sorts. This did a great job of reducing the available air space - the pot pressurized in about 40 seconds - but the shelf was (unsurprisingly) unstable, and at some point, either when the air was coming in or during the casting, the mold ended up tipping and spilling. So I'm back to the drawing board, but thought I'd check with others to see if anyone else has tackled this issue successfully, before trying a few other ideas. Thanks!

 

[Edgar]

I put block of wood in my pot so I wouldn't have to reach to the bottom of the pot to set the mold inside. While not for the same reason, you might try wood instead of water - it would definitely be more stable.

 

[Curly]

Any solids should work. A disc of plywood on top of marbles, pebbles or rice should do it I would think.

 

[Amanap]

How about a bowl like an ice cream bucket or Tupperware bowl with a lid. Fill with water and poke some holes in the lid so the pressure will equalize.

 

[sorcerertd]

If you don't mind extra weight, a couple bricks would work and will still provide a stable surface in the pot.

 

[PatrickR]

i would use sand.

 

[its_virgil]

Water is not a good idea on several levels but especially if casting with Alumilite Clear Or Clear Slow. Both are VERY sensitive to moisture.

 

[Painfullyslow]

Sand is likely your best bet. Easy to add, easy to remove. If you are concerned about dust you can always lay something on top of the sand surface but it should not be a problem as long as you are careful when inserting your mold. Worst case scenario you get dust on the top of the curing blanks which you turn off anyway.

 

[JohnU]

I'd worry the air pressure would blow the sand around the tank and in the mold. . . I've blown resin out of molds inserting pressure. An early lesson. Also, Sand is heavy and may sink into the resin. Definitely not good for clear casting.

 

[PatrickR]

i would definitely cover the sand with a piece of plywood cut to fit. We should all be applying and releasing the pressure slowly especially with the molds elevated close to the in/out ports.

 

[JohnU]

i would definitely cover the sand with a piece of plywood cut to fit. We should all be applying and releasing the pressure slowly especially with the molds elevated close to the in/out ports.

I totally agree with you, but it only takes one grain of sand to get where you don't want it in a clear cast to ruin the blank. I wouldn't put thousands of them in my tank to worry about them. Maybe I'm just over cautious knowing my own luck. Lol. I think I would find something more on the solid side.