PVA is 2-4 mils thick in a heavy application (0.002"- 0.004"). It can be applied thinner to aluminum (0.001-0.002"): http://www.rexco-usa.com/documents/TDS_Partall%20Film%2010.pdf If 0.002" is a concern to you, go ahead and not use the PVA. PVA guarantees a release every time.
So does waxing the bare aluminum beam and not going through the extra step with PVA. I've seated more than my share of beams and they all released with a slight tap with a rubber mallet.
