I’m still grappling with the problem of bubbles in my castings. The accepted wisdom indicates that you want to set polyurethane castings under pressure so the bubbles become very small. I think the Smooth-on site suggests 60 psi (413 Kia).
Not having anything that holds pressure, and not wanting to spend a lot of money, I took a trip down to the local Sally Ann and came back with a pressure cooker. Now pressure cookers are only supposed to work at a pressure differential of 15 psi or so – far below the recommended 60 psi. I reasoned that for my little castings, maybe 15 psi would be enough.
I circled around Rona and Lordco and came away with some useful fittings, which I plumbed into the lid. Then with a careful eye on the gauge, I started to fill it up.
Yep, the pot was $7 for a reason: the gasket was shot, and the pot didn’t hold air at all! A paper gasket didn’t make a good enough seal either. Back at Lordco, a helpful man sold me a probable-looking tube.
Now the pot holds air just fine, but the lid is permanently attached to the pot. Maybe I should have plumped for a proper pressure vessel after all.