Melty glue, make my plastic good as new.

April 8, 2009 10:23 AM

When hard plastic breaks is there any adhesive that will 'weld' it back together so it won't just snap again at the glue point under pressure?

You know how when hard plastic breaks it usually does so in a random topographical pattern such that you can fit the pieces back together perfectly, if only there was a glue that would hold them indefinitely?
I know there are all types of glue out there for all types of solutions. I am wondering if for broken hard plastic there is any glue that will make it at least as good as new if not better.

posted by GleepGlop to home & garden (8 comments total)

plastic welding
posted by hortense at 10:27 AM on April 8

J-B Weld fixes everything. It looks like hell, but it's pretty indestructible.
posted by electroboy at 10:33 AM on April 8

Seconding J-B Cold Weld. But let it cure 24 hours.
posted by Blazecock Pileon at 10:56 AM on April 8

J-B Weld won't stick to Polypropylene or Polyethylene plastic (not surprisingly as practically nothing does).
posted by Mitheral at 11:34 AM on April 8

I have used this to fix a broken side mirror on my car. It is very strong, and depending on how much you can apply, and how much leverage the repair will be under, it may work for you.

It's a bit messy, and your repair may not end up looking like whatever unbroken object you started out with.
posted by Danf at 12:06 PM on April 8

Cyanoacrylate-based glues (e.g. superglue, krazyglue) work well for gluing some types of plastic under some circumstances (e.g. no shearing, but don't want to make a mess all over the part, need fast cure). J B Weld is awesome. The general case answer to this question though is to check This To That.
posted by jeb at 1:40 PM on April 8

Interesting, well that J-B weld looks like the LePage epoxy that I had picked up at the hardware store, so I guess I'll give that a go, thanks!
posted by GleepGlop at 2:11 PM on April 8

This may be too late for you, GleepGlop, but maybe will be useful to others. Mr. Informed recently broke a knob off our early-1980s stove (so, no way of replacing it!). This knob had a hard plastic shaft that broke off nearly flush with the surface of the stove--much to our dismay as it controls the exhaust fan. Any join had to be strong, because the knob needs a firm twist to start the fan or turn it off. The two pieces still fit together perfectly as you described. After considering other solutions (epoxy paste, a metal pin, etc.) I tried using Gorilla Glue superglue and let it set for a few days. Can't say if it "welded" the shaft back together, since I can't see under there, but the join is strong enough to use the knob again.

(Note that regular Gorilla Glue doesn't bond to hard plastics and will foam up, making it hard to make a neat repair; this superglue was one of the few glues in the hardware store that WILL bond hard plastic, and it was easy to control.)
posted by Ms. Informed at 7:43 AM on April 9