any way to tell a Polycarbonate,plastic,fiberglass helmet from one another?

[modifiedamerican]

i have a old vintage motorcycle helmet. but the padding and everything is missing on the inside and im not sure what it is made out of. i no painting fiberglass,plastic is no biggy but from what people have told me and from what ive read, u dont want to paint Polycarbonate. my question is, is there anyway to tell what my helmet is made out of it? thanks alot!

 

[4eyes]

Is it smooth on the inside, and edges. Or can you see fibers?