Photograph

The pressure-gauge, holding a deep vacuum in this picture. The scale is in bar, from 0 to -1 bar, the maximum achievable, and representing the inside pressure in the resin trap. What is a deep vacuum? Well, at least 90%, but preferable more, lower than the outside pressure. Presuming outside pressure is 1 Bar = 1000 Mbar = 29,53 Hg, this is at least a pulling of 900 Mbar = 26,58 Hg But the deeper the better.