Plastic Welding

[mkory]

I've got a really bad crack going through the bottom lip of my bumper (right under where a fog light would go) on my car. I've got a friend that does some schooling at one of the local colleges during the day and he said they could plastic weld it, but first, they need to know the kind of plastic my bumper's made from. Does anyone know what kind of plastic the bumpers made from?

[mkory]

It's a '95 with the stock bumper.

[[Zero-S]]

Urethane.

[rivetapproved240]

i had the same problem. i have a 95 as well and all i did was sand it, ad jb weld ( not jb kwik) clamp it so that it wont move until it dries. let it sit over night. (apply the jbweld to the area where it wont be seen. ) get some kwik steel and apply it to the part of the crack that can be seen, smooth it out with wet fingers. and then sand and paint. (i wouldnt advise sanding the jbweld. only sand the kwik steel.) prime it and paint it. its a lot simpler than it sounds.. i do this about every 4 oil changes so that it looks new.

[mkory]

Well, I was going for some kind of plastic welding that I could use on the inside of the crack, that way I wouldn't have to sand and repaint it. I don't mind seeing the crack but I don't want to let it get any worse.

[Ligouri Rd]

There is no plastic welder that will work with that plastic. Urethane is a therosetting plastic, it is molded from a resin and a catalyst. Once the plastic is chemically formed nothing will desolve the bond. Thats why paints don't stick to it so well. Your best bet if the crack is not to wide is to try to clamp it so that the crack is hardly visible. Use jb weld or fibreglass and resin on the back side. Make sure you spread the glue (and glass if used) out as far as you can. The only way that stuff can stick is by having a big surface area to grab on to. Hopefully when you are done the crack will be small enough not to notice. Don't be too suprised if the glue works its way loose in a few years.