UKC

The foam insert has detached from the plastic shell, and I know that I need to be careful what glue I use, as solvents will dissolve the foam.

What glue should I use?

In reply to KA: I'd ask the manufacturer.

In reply to KA:

Polyurethhane woodglue (builders merchants) would be a reasonable choice, Epoxy (Araldite, everywhere) would also work. Neither should harm your helmet assuming it's either EPP or EPS foam in a Polycarbonate or Polystyrene shell. The Polyurethane glue remains flexible once cured and sticks to most stuff.

On the other hand a decent double sided tape is likely to be adequate and it's cheap/clean.

No guarantees though, if you're worried about it call the maker/distributor (who'll likely suggest replacement).

jk

In reply to KA: ...and not affect the plastic of the helmet either....even if its polycarbonate rather than polystyrene there was a (occasionally bonkers and occasionallt useful) thread about helmet stickers and solvent glues. The formulations of the glues which stick foam to cycling helmets etc seem pretty specific to the manufacturers - anyone know if silicon sealant is OK - gives off acectic acid when curing but that should be ok?

In reply to jkarran: ....you beat me to it...just typing as you posted...good to know that epoxy or PVA poly vinyl acetate will be ok...whats' your take on silicone sealant - same by product as PVA when curing?

In reply to timO:

Don't know about silicone, to be honest, I don't like the stuff so I don't use it but I doubt the small amount of acid given off will do much harm. It's not like you need a lot to put a helmet back together. I don't think PVA will stick very well to the shell but I'd not be concerned about it attacking the plastics.

Superglue (or at least the gelled stuff) is great for putting foam model planes* back together after a heavy landing.

*read 3d EPP jigsaw

jk

In reply to jkarran: Thanks for that, so the Evostick Wood Adhesive I've got in the house should be fine?

In reply to KA:

dont use glue.
use that double sided self amalgamating tape stuff plumbers use. its a little thicker than a layer of glue, but way more solid with none of the worry. totally water.

i did a canyoning helmet 3 years ago and its bomber.

used it on ice tools as well - fantastic even after 2 long seasons, but sticks to everything else as well.

In reply to KA:

I asked Petzl this after the inside of my helmet detatched - they just replaced it for free.

In reply to KA:

If it says Polyurethane or PU on it then yeah, it should be ok. Try a little bit out of the way on the shell and the foam first to be sure. This'll also verify it does actually stick, some plastics can be a real pain!

jk

In reply to jkarran: Thanks for the help! I'll give it a go.