I have a ring of expanded polystyrene foam, which has snapped. The cross-section of the ring, i.e. the surface area of the break is small, about 2cm square.
What's going to be the best adhesive to repair it?
Daniele
PVA is probably as good as anything. You can't use anything with an organic solvent or you will end up with a horrible gooey mess.
as an avid model plane man,. you have three or four options known to work.
1/. PVA. yes simple white glue. It will however take a week to dry because polystyrene don't let the water out, so we genereally use it to attach things like balsa to polystyrene, where its light and very strong.2/. foam safe superglue. This is model specific as its a fast superglue that does NOT turn poly into a soggy puddle as most superglues do. I never found it very effective
3/. Epoxy. It doesn't bond that well but it bonds stronger than the poly. It is however heavy and much harder than the poly, so we tend not to use it that much.4/. Hot glue. This is the best of all. 240v generator and a hot glue gun gets a foam model back in the air in minutes, even if it looks like Frankenstein's monster.
It has good flexibility fast grab and set and is not too heavy.
The finished joint is more less like a lighter and more flexible version of epoxy, and like an epoxy repair, the next time it crashes it always breaks somewhere else :-)
do not attempt any solvent based glues - they all attack the styrene, as does Cyanoacrylate superglue and polyester resins (car body filler)
Glues based on PVA and other acrylic type stuff work, but take a long time to get the water out of. So e.g you can use decorators caulk to blend with poly, but it takes forever to turn rubbery.
Well I'm surprised, but I'll give that a try. The foam-safe CAs seem to be very expensive.
Daniele
Evo stick? Pretty sure I've seen that on the back of polysytrene tiles. I'd do a test first though just incase the solvent does what solvents do...
Trouble is it has no structural strength, so gluing seems not to work. Most glues seem to be mild (or not so mild) solvents and then the fix looks messy and ugly. Brian
Be careful. some sort of petrol like solvents dint attack poly, but glues with them in are well nigh impossible to source due to sniffing etc.
And the evostik on the back was a water based contact...
Evode used to make a PVA based adhesive. The normal rubbery impact adhesive uses organic solvents and will dissolve expanded polystyrene.
I was thinking something like that. I have never tried it and can't imagine having to but if you spread the glue on surface A and let it dry, as long as you keep off the dust, you can leave it indefinitely, the same with cyanates I believe. (That actually worked on a burglar for me.)
Can you spread some on a stretched skein of film such silk and then apply that to the broken piece "B"?
I imagine tape would do as well but I'm not sure what you requirements are. No piccies?
largely polystyrene of the expanded kind fractures on the joints between the bubbles. It is not suitable for tape repairs.
Neither is contact particularly good - you need a gap filler.
in my case hot glue is no 1, followed by lightweight polyfilla to make good the fracture line at the surface, and then re-covering with whatever you used to make a decen't finish in the first place. Tissue or brown paper and pva plus an acrylic coat is then suitable for most paints.
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Evo Stick certainly used to do a polystyrene ceiling tile adhesive, but it was nothing like regular Evo Stick. The ceiling tile adhesive worked very well, but may have relied on drying through the ceiling.
I had an expanded polystyrene carving kit (hot wire, glue, etc) as a child. That came with small tubes of glue which worked, but I've no idea what it was.
one of the UHU derivatives works too..cant remember which.
I can confirm it worked very nicely, thanks! Not beautiful, but it seems pretty strong.
Daniele
Why the generator and 240V hot glue gun? Why not a lighter gas powered one?
SteveW
Or a 12v one. Or an internal battery one.
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