Your explanation seems to imply that eventually (given a long enough pot-life and a great vacuum pump) all the resin will wind up in the catchpot and the fabric will be dry again. - I don’t think it works that way…
*(Disclaimer: I’m a newbie and mean no disrespect - please correct me if I’m wrong, preferably via tested pieces.)
My reasoning is as follows:
(Lets assume the bag and connections are 100% air tight and there are no out-gassing issues to deal with):
I think we all agree that Resin Infusion works due to a pressure differential between the pump and atmospheric pressure. At the start of an Infusion there is nearly a 1000mbar pressure differential between the part in the bag and the atmospheric pressure forcing the resin into the bag. During the Infusion, the fabrics near the resin inlet tubing will tend get flooded (over-saturated) because resin is getting pushed into the bag faster than it can migrate throughout the fabric.
If the part you are making is for a cosmetic application, then it may be better to clamp off the INLET and VACCUUM lines after the part is infused(?) Doing so will seemingly allow atmospheric pressure acting on the outside of the bag to somewhat “self-level” the excess resin near the inlet throughout the part and end up creating a resin-rich part. This part will be stiffer (due to excess resin) and may be exactly what the specifications call for, but will certainly be heavier and from what I can tell, it will also be weaker.
On the other hand, if the part you are making is for strength, then you will require a higher fabric:resin ratio.
(From what I can tell, 60:40 is optimum(?))
Anyway, once your part is fully infused and the resin intake is clamped off, the vacuum force acting on the part will continue to pull excess resin from the part into the catch-pot. The key word being “excess” - once that excess resin is removed and the part has reached a pressure equilibrium between the bag and the pump, then I believe there will be no additional resin migration regardless of how long the pump is running.
The blurry part for me (and it may be totally dependent on what type of resin and fabric you are using) is how much resin will actually be left over once that equilibrium is reached?