I was watching YouTube videos on metal casting, as one does, and I came across a clip of a guy throwing his plaster in the vacuum chamber before pouring it over the wax he was casting. I was struck with a thought. When you put water in a vacuum chamber, the water is bubbling, not because you’re pulling out air trapped in the water, but because the lower pressure means that it boils at lower temperatures. So when you put plaster into a vacuum chamber, how are we sure that the bubbles forming are air coming out of the mixture, not the water or the mixture boiling away?
You are unlikely to take enough water out of the plaster to matter. And any bubbles you create of water vapor will collapse when you return atmospheric pressure. And the boiling action may help shake loose the now larger air bubbles.
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Your looking about 20,000 microns before you get boiling about room temperature. That will take a while to pull down.
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Unless you pull the s headers, use big hoses, and an Appion pump……just messing with you Tim