plexiglass cracked dome repair

[anadem]

Please can someone point me to info on repairing a cracked plexiglass dome?

In this case the appearance isn't important, it's just a question of sealing it. There are two cracks - small one is radial, about 4 inches, the longer is circumferential two inches in from the edge and about 12 inches long. I can't replace the dome at present, unfortunately.

(Search found a reference to an article "Choosing and Using Sealants" by Don Casey, but it seems to have gone.)

thanks!

[timebandit]

I used some stuff in a clear squeese tube, just put in in the crack for a temp fix. It has been there for 2 years and is still clear and almost undetectable. I am sorry I dont remember the name but I think I got it at a hardware store. It might have been something by GOOP.
You will know it because you can read through the tube it is that clear.

[sailingdog]

Plexiglass is an acrylic, and as such has several good solvents that will repair the cracks. I'd contact a sign supply company, like Hart Supply, in Hingham, Mass. and ask what acrylic solvents that have a filler they have available.

I wouldn't use a sealant on the Plexiglass itself. Many of the sealants, except for the silicones, will attack the Plexiglass themselves, due to their chemical composition. The silicones aren't really adhesive enough to work in this type of application IMHO.

[Milla]

Hi.

We used to repair plexi glass on Glider (sailplanes) hoods with ordanary epoxy - but also drilled a smal hole at the end of the "hair" crach to "stop" the crack and stress problem in the plexi.

[jones2r]

If the epoxy repair sounds attractive to you, Loctite makes a two-part, clear product that, while not flexible, is not totally rigid (if that makes any sense). It should make a minimally obtrusive repair. I've gotten it from Ace Hardware.

IIRC, the solvent that Dog mentioned is methyl chloride (working from memory here). It "welds" the base material.

[anadem]

Thanks everyone ... I'll try get a solvent. Past experience with epoxy on plexiglass has been that it doesn't bond well. I was tempted to try some kind of silicone/acrylic caulk but if I can get solvent (and not poison myself -- iirc methyl chloride is nasty) that will prolly make the best bond.

Thanks again for all the ideas.

[sailingdog]

Anadem-

They do make a version of the adhesive that has some acrylic dissolved in it...and will do a better job of patching the crack.

[the1much]

a dude told me about stuff specialized for lexon, plexi-glass, and plastics,," methylene chloride" it comes in a bottle with a needle tip. says it welds it. this is the thread,, i havent tried yet but am going to monday. http://www.boatdesign.net/forums/showthread.php?t=19698