I recently got a bunch of signatures from a bunch of pros on my helmet. It was a very expensive helmet so before you say, "Just put it in a box in your closet." I really can't because I just bought it last year and I don't have the money to buy a brand new one. Plus I still want to use the helmet anyway. I was just wondering if there was a way to protect the signatures, something that won't fade, smear or take off the signature (obviously) and won't wreck the graphics on the helmet itself. The signature was done in sharpie, not sure if it matters or not. I've heard people say clear coat nail polish, clear coat spray paint, mod podge, etc is a good way but idk.
Generally sharpie is pretty good with staying on plastic in the first place but if you really want to preserve the sigs in mint condition...
I worked in a paint store and would reccomend a rust-oleum clear coat. Matte if your helmet is matte, shiny if it's shiny.
They also have a clear coat specifically for plastic but I have no experience with that. Both nail polish and that glue stuff will make the surface of the helmet look really weird and uneven but the spray paint should do the job.
Make sure to tape any parts you dont want covered and then spray in bursts from like a foot away until the helmet is covered. Do that for at least one more layer and u should be good.