Since we are being cheesy here...
There used to have a helmut working at my office, he was such a nice little german guy. But he did have an annoying german accent with all that 'gher-uuom-laud' stuff, and I now understand why somebody would want to paint him, maybe red or something, but i think the chemical thing would be a bit too much for even the little krout to handle.

But seriously, I met mark martin, #6 Rousch Racing and had him autograph my helmet last summer, he signed it in HUGE script across the back. I sprayed some clear coat poly over it so that it wouldn't rub off. I put it on real thin, 3 coats.....
It seems to have done ok. You won't have any problem painting it. It'll be fine.
Hey, I'm just having fun, eh?