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vac chamber not doing much

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vac chamber not doing much

Postby burner010101 » Wed Feb 24, 2016 3:39 am

I bought a vacuum chamber (since I'll need degassed silicone molds for when I get a pressure pot).

I mix up SmoothCast 327, rev up the pump to -29 Hg, turn it off, then let it sit in the chamber at -29 Hg for 7 minutes. Still bubbles!

Strangely, the resin bubbles like it's boiling in the chamber, but it doesn't really rise like I see in videos. Nor does it have that collapsing moment where most of the bubbles disappear.

:(
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Re: vac chamber not doing much

Postby zazie_rx » Fri Feb 26, 2016 2:50 am

The bubbles will still look present until you slowly let air back into the chamber, then you should notice it immediately smoothing out.

You're vacuuming after mixing part A and B together right?

Most of the videos you've probably seen bubbling up are silicone, resin isn't as rubbery and elastic as silicone so it won't bubble up so much. If after vacuuming for some time and you still have bubbles, then you might just have too much resin to vacuum out completely in 7 minutes. Try putting your resin into a shallower container so the vacuum has more surface area to work with.

Hope this helps
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Re: vac chamber not doing much

Postby mangozac » Fri Feb 26, 2016 7:48 am

I'm not sure that resin ever stops bubbling when under vacuum - I believe once the air has boiled out some of the resin components begin to vapourise. For degassing the resin I vacuum for less than a minute (and it's done while the resin is in the mould).

Zazie makes a good point - the degassing process is much more obvious with silicone than with resin!
Oh yeah I can make that....
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