Flex 30 not curing fully

Good questions.

Here is the process I would recommend since you have Pressure:

1) Shake both A and B.
2) Preheat your mold (130F for 15 minutes or if it is silicone ... 1 minute on high in the microwave per lb of silicone)
3) Measure equal amounts by weight
4) Mix thoroughly for 1 minute or
5) Pour slowly into your mold to avoid introducing any new air bubbles
6) Pressure cast for 45 minutes at 30-50 psi.
7) Remove from pressure and post cure for 1 hour at 125-130F.
8) Allow to cool
9) Demold

The lower Flex series (30 & 40) will pick up dust/lint more than the stiffer Flex series (60-80). The lower Flex series urethane rubbers have more surface tension and pick up debris more easily but should NOT be "tacky" or "sticky". I would describe it more like static cling than tacky.

By all means, use pressure to ensure the best physical properties of the Flex.

Lastly, if you are casting a thin or small piece, it takes longer for it to cure as it doesn't generate as much exotherm on its own. So preheating your mold and post curing becomes more important.

Mike