Yeah, the application system is probably the tricky bit, rather than the paint.

> Any dissolved gasses or moisture can usually passively sort themselves out due to their differing masses, but again, not in microgravity.

This is a solved problem with the ECLSS system [1], required from humans releasing ~3.3 lbs of water per day, and exhaling gases that must not accumulate or form dead zones, and normal VOCs scrubbers [2] due to most modern materials releasing them.

I suspect it would be more of a "how many extra filters do we send" type problem and cycling the collected water a couple more times.

[1] https://www.sciencedirect.com/science/article/abs/pii/S13640...

[2] https://www.researchgate.net/figure/Typical-concentrations-o...