Reinforcing styrene armor/helmet - help/advice required


Active Hunter
I've experimented with some fibreglass resin and also some car body filler on the inside of my styrene helmet. I put a 2" square of each on the inside just to test whether they'd eat right through or whatever. Well, they both set great and looked like they were adhering well, but the car body filler came off when I flexed the helmet and the resin also lifts off when I gently tested it with a knife blade.

On the positive side, there wasn't any sign of damage to the styrene. I guess for a helmet it'd be OK if the entire inside is coated, but for something like the gauntlets it looks like it will flake off with normal flexing. The car body filer contains styrene, so I figured it'd really grab on, but it acted like the styrene had mould release on. I put both samples onto the shiny side of the styrene - could that be the problem?

Any advice, folks, please?
Shiny side? That's a good possibility for the product failure. Try scuffing it up a bit before applying. Also, I would think that a larger area would tend to make itself adhere better. Make sure that the area is also clean, dry and free of grease/oil/blah, blah, blah, before applying. If you use fiber cloth, leave a bit untreated at the edges to allow "feathering" of the contiguous applications. This way, it's all one piece. There are more experienced hands with this stuff here, so I defer to the experts.
I reinforced my styrene backplate with 4coats of fiberglass,and it worked like a charm.I did sand the entire inside thoroughly to get every nick,and cranny then wiped it down with rubbing alcohol.After that it was just a matter of glassing it up,and then trimming it down.Beware of one thing,and that is the heat generated by the epoxy curing can/could cause "droopage" on some thinner peices of styrene.

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