What on
Stormtrooper Stunt Helmet 10th Anniversary Edition. | RS Propmasters isn't accurate?
I am not aware of much evidence to show how an individual original helmet flaked over the years. Usually the later photos are decades later. Obviously those helmets were treated pretty roughly during filming and sometimes in the years after filming.
The originals certainly did flake, even while making the film. I don't know if the original plan was to make the screen used armor the same way as the stunt helmets or not, but it would make sense for that to have been the plan. They must have realized the problem with painting Polypropylene since the TK armor, hero TK helmets, and TIE Pilot helmets/armor were all made with bare ABS, not painted Polypropylene.
My RS 10th Anniv helmet still looks the same as when I received it.