Well everyone seems to think it was a gelcoat, but in fact it was not. And if you're after a "look" then you should explore everything that makes it look a certain way....in this case, beating and scratching it up etc.
Ok so we all know they added the grey out of neccesity after the black. For me I used a paint marker cause I was just too lazy to mask it off but the result was positive.
So in order heres what I did;
1.) Apply thick auto paint with a brush. I only did this for the type of brush stroke lines I wanted to achieve.
2.) Spray the face with the bumper coat.
3.) Apply the aluminum paint with a brush making it blend with the bumper coat. (of course we let the paint dry before the each coat)
4.) seal it with clear or smoke. Brush on smoke where you want it to be darker.
5.) Add wax. The wax gives it a neato look, but its a little more slippery to hold. I discovered this by accident but it has a positive result. remember not to get it on too thick....just so you know its there.
6.) If you do the black my way, do it last. I then used rubbing compound to the left cheek and buffed it with an air wheel.
This is pretty close to what i remember as I do not have specific system, I just go until I'm done. I weathered it somewhere in there but do it before the wax.
Hope that helps!
Having said all that, I expect finished pictures of your helmet for all of us to enjoy in return when you're done!!