Fiberglass to Styrene Question

[TridCloudwalker]

I snagged this really cool, ridiculously inexpensive vac-formed styrene Ep.III Clone Trooper helmet, and I wanted to strengthen and thicken it up so that I can properly accurize it. Will putting a layer of fiberglass inside be safe and actually stick, or will the heat from the curing cause warpage?

If fiberglass isn't do-able, what recommendations do you have?

I'll be completely removing the horribly soft and too wide mohawk, and scratching a new one, I'll be reshaping and thickening the visor area, and I'll be sharpening the detail in the chin/mic-tip areas.

 

[Raffles]

What I'd do is score the inside with a craft knife and skin it with a coat of car body filler. Then I'd put on a few more coats and then Fiberglass.
Where'd ya get the dandy helmet?

 

[exoray]

Will putting a layer of fiberglass inside be safe and actually stick, or will the heat from the curing cause warpage?

Yes, and yes...

As for the heat from curing and it causing warpage if you don't over catalyze it and pay attention you should have any issues... Less catalyst = longer cure times and less heat... As for the amount there are so many factors like temperature and humidity that come into play, so practice is your best friend...

You might want to consider an epoxy resin vs a polyester as it's not as nasty to work with and sticks better to existing surfaces...

Do the fiberglass but have a boil of water and a towel handy, if the outside of the helmet starts too get hot, take a damp towel and lay it on the styrene to pull some of the heat off...

 

[TridCloudwalker]

BY car filler, you mean Bondo...not gasoline? That's all I ever seem to be filling my car with. lol

I got it in the Junkyard. It was the only one he had, and it (he thinks) originally came from a prop/costume seller in China.

 

[exoray]

BY car filler, you mean Bondo...

Bondo is actually a brand name of the 3M corporation, but yes it has become the generic name for polyester car body filler...

If you cut it 1 part polyester fiberglass resin and 2 or 3 parts body filler you can get a nice brush consistency mud... Make sure to double hit the catalyst for both the body filler and the resin, technically they are the same as most body fillers are just polyester resin and talc, but I prefer to always be safe as some of the newer professional body fillers are fancier formulas...

 

[TridCloudwalker]

Bondo is actually a brand name of the 3M corporation, but yes it has become the generic name for polyester car body filler...

If you cut it 1 part polyester fiberglass resin and 2 or 3 parts body filler you can get a nice brush consistency mud... Make sure to double hit the catalyst for both the body filler and the resin, technically they are the same as most body fillers are just polyester resin and talc, but I prefer to always be safe as some of the newer professional body fillers are fancier formulas...

Ooh, I like the mud option. seems a lot easier to skin the inside like that than with the normal putty consistency.

And I don't need to make it too thick. It's fairly sturdy as is, but I just want to give it some extra oomph.

 

[Jumpin Jax]

Bondo is safe if you mix it right. What I would do is use less hardener to cool the setup process; slower but you're not in a hurry. To get a smoother interior(no sharp peaks, hooks) you can lay cling wrap on top of the setting putty. It will peel off once dry and you can control how high it stacks. I don't work in FG, filler will stiffen it up just fine, it's also easier to repair than any other method I know.
JJ

 

[TMBountyHunter]

Bumping because I'm building something out of styrene and was hoping to reinforce it.

Found two more relevant threads
http://www.therpf.com/f9/can-i-back-up-styrene-fiberglass-54690/
http://www.therpf.com/f11/fiberglass-reinforcement-styrene-glues-379/

The consensus seems to be less hardner if using polyester resin, but I'm curious as to how much less? Also how much longer would the curing time be? I'm in a bit of a rush. Also from my experience the smell persists for longer when there's not enough hardner so also in he do not wan category....


Should I just go straight for epoxy instead of polyester?

 

[robn1]

...Should I just go straight for epoxy instead of polyester?

With the thin application used to laminate fiberglass I don't think heat would be a problem. I've used Smooth-On's Epoxamite (medium cure) epoxy with fiberglass and it only got moderately warm, it shouldn't be a problem with styrene.