Well I can remember it was a VERY meticulous process to get every molecule on one reagent to react with and neutralize its *opposite and leave nothing of itself behind.
So splash and wash is going to leave excess 99.9% of the time and why the second step of neutralization is needed. (I am not a Chemist though I play one in my garage)
On your test I suggest one piece thats ospho'd, neutralized, and then left out with the others.
I saw an HD Springer Front end forks I did a year or two ago for a friend the other day.
They sat in my attached garage for many months then in his inclosed but open and leaky shed since. All they need for epoxy prep right now is some light surface rust scuffed and removed. (YMMV)
The real test I have not seen is one between a proper PPG, SPI or BASF epoxy primer and any of the MCU (moisture cured urethane) Epoxy products. POR15 and the like.
Which has the best flexibility after it's cured?
If it bends and cracks it's going to rust. If it bends and holds it will Resist russty formations at its foundation.
Hmmm
