OT working with acrilic plastic

Today I had a little problem develop in my bathtub in the form of a small crack. The tub is acrylic plastic, and the crack is about 2 inches long. First off, I drilled both ends of the crack to stop the spread, and I went down to Home despot and bought some sheet acrilic made by "Plaskolite". My plan is to prep the area around the crack, and using some 5200 marine sealer/cement I want to glue the sheet down over the cracked area. Looks don't matter, since we want to eventually remove the tub altogether, and put in a tile shower. all I want right now is to get a good seal to keep the sub floor from rotting out. The area isn't perfectly flat, so my question is, can I heat the acrilic sheet with a heat gun and then form it to the profile of the area that I want to attach it to? Any thoughts would be appreciated.

G'day Loggerhogger

Yes, heat guns can be carefully used to heat the acrilic to a softened state. Don't over soften it, as it will make moulding it tough. Don't forget to mark the patch and the tub before you remove it, so you can put it back on the in same place.
Use chlorilform to glue the pieces of acrilic together. It melts the surfaces and molecular structures together, so they become one piece.

Easy done.


Cheers,

Phill.

Mek and acetone are 2 other solvents that will solvent weld it.

I'd stay with the 5200 rather than a solvent bond. The reason is that the solvent bonds may crack when the material flexes. Be careful with the heat. Since plastic is not a good heat conductor, the surface closest to the heat may overheat and bubble before the back side gets hot enought to conform to the tub curves. You would probably want to tape the edges of the plastic down and leave it for a couple weeks to ensure curing of the 5200. Good luck. WWQ

Bill made an excellent point about the 5200--it is slow curing. One week minimum, but, as he suggested, two is better.

Another product that will work is the marine caulk "Life-Calk." It will remain more flexible after curing than 5200. If your patch is in a place where it gets stepped on or otherwise flexed, it may work a little better. But the 5200 also retains some flex after curing.

I found some quick cure 5200 that cures in 24 hours. I am thinking of using acetone to clean the surfaces before applying the glue. the instructionson the glue said to avoid the use of alcohol since that will affect the cureing. Unless I'm mistaken, acetone is petrolium based so I should be ok...Right?

Thanks to all for the replies.

Sea Farmer said:

Bill made an excellent point about the 5200--it is slow curing. One week minimum, but, as he suggested, two is better.

Another product that will work is the marine caulk "Life-Calk." It will remain more flexible after curing than 5200. If your patch is in a place where it gets stepped on or otherwise flexed, it may work a little better. But the 5200 also retains some flex after curing.

Click to expand...

Life Caulk is a polysulphide and doesn't have much of an adhesive bond, unlike 5200 which is a polyurethane.

Either 3M 4200 Fast Cure, or 5200 Fast Cure should do the job in a reasonable timeframe.

Acrylic bathtubs are usually made by putting a very thin acrylic sheet into a mold and then building it up thicker with a number of layers of glassfiber matting and epoxi resin.
So, the underside of your bathtub is likely to be conventional fiberglass and epoxi resin.
If you can get to the crack from underneath that would be the best place to do the repair with resin and glassfiber matting. You may not be able to get near the crack if like in my bathtub there is also a plywood board to add strength. Bathtubs without such a board are very fragile. My brother, a bathroom fitter and tiler had just about finished the final tiling on a job when the owner, fitting a curtain rail, dropped a claw hammer into the tub.
It went straight through.

Davycrocket

Davy, this one doesn't have any fiberglass what so ever in it. It is a piece of molded plastic about an eighth of an inch thick. I'll never buy another one.

Not to go down a rat hole, but aren't these things (and shower stalls) supposed to be installed on a puddle of cement to add some bottom reinforcement?

Walt

Normally they are, but this one had a molded plastic base that was glued to the bottom with feet that was supposed to support the bottom without having to use cement. After we got it installed, we could feel soft spots which I filled by injecting filler foam under the tub through holes drilled up from the crawl space. the crack occured in one of the last soft spots which I could not get to from down below, so before I glued the acrilic sheet down, I drilled the ends of the crack to stop it from spreading, and then used the holes to inject more filler foam and support everything. As stated before, this was supposed to be a self supporting tub acording to the instructions, but it failed miserably. I know that the repair sounds kind of hoky, but it is only to keep from rotting the floor out until we can get the money together to replace the whole thing with a walk in tile shower. Ah! the joys of home ownership!!