Best way to reinforce a resin helmet?

[Ackbar16]

I was hoping some folks here could give me some advice on how to reinforce the thin areas on my resin Deathtrooper helmet? I can’t decide if I should fiberglass the interior, or if adding a few more coats of resin would be best.

As you can see from the picture of the interior, there’s an area that is so thin, there are actually tiny holes. Nearly every crease on the face is paper thin, and I’m afraid to put any pressure on these areas. Would a few more coats of resin on the inside be enough, or would fiberglass be a better option? I have the supplies for both, but don’t really have much experience with either.

Any advice would be much appreciated!

 

[TazMan2000]

Resin may work, but some resins may not stick, unless you sand down the area, and even then there still may be a problem.

I would used several thin layers of two part epoxy.

TazMan2000

 

[shenphong]

If the rest of the helmet is pretty solid, use apoxy putty to fill in the thin areas. You can fiberglass it as well, or combine the two, but if the rest of the helmet is solid, it isn't really needed. What TazMan said, if you try to add resin, depending on brand etc, you risk it not bonding.

 

[Gerard2567]

Use the same material it was made from.
Urethane resin. Just make sure to sand it heavily to give a surface that a next batch can stick to. Fibreglass/polyeater resins in my experience dont stick well to urethane resins because they're just two completely different animals.

Epoxy putty or bodyfiller may work but again, focus on preparing the surface to be reinforced. Otherwise your reinforcement will be for nothing.

 

[Darth Lars]

There are different types of urethane resins, and the resin that had been used to rotocast that helmet may not necessarily be a variety that when already cured bonds to new resin. I think very few varieties of resin do, at all: providing at best only a close mechanical fit that is likely to break eventually. If you really want to use resin, for whatever reason (to carve out sharper details, maybe?), I would want to ask the maker of the helmet about the properties of the variety he used.

I have done similar reinforcements of a rotocast Clonetrooper helmet, using patches of fibreglass. Epoxy resin is what to use for reinforcement, as polyester resin again does not adhere as well.
I applied clear packing tape on pieces of fiberglass weave so that I could trim the edges and make each patch fit where I wanted to be put. I brushed thick epoxy inside the helmet where the patch should go and stuck it there, pressing with my fingers. When it had cured, I pulled the tape, which (because it is of PE) came off cleanly and brushed on more epoxy. When that had cured, I used a sharp knife to cut off any edge of fiberglass that had risen anyway and used putty to blend the edges.

 

[Ackbar16]

Thank you for the replies everyone. I currently have Bondo putty, Bondo fiberglass sheets, and the resin to go with it.

Based on the suggestions here, there’s a chance the resin might not bond properly? So I’m thinking the Bondo putty might be the best option to start. I really like that fiberglass technique, and may use it in the future. I’ll give the putty a try this weekend, and see if everything works out.