Yes, a huge factor is the outgassing of materials. While just solidifying and a long time after that, it gases off solvents and other small particles that you c

Yes, a huge factor is the outgassing of materials. While just solidifying and a long time after that, it gases off solvents and other small particles that you constantly have to pump away and that raise your pressure noticeably. In cryogenic environments this is less of an issue because things are more sticky, but in a room temperature apparatus targeting ultra high vacuum this is troublesome or impossible.