Can JB Weld structural plastic adhesive be used as body fill?

I am repairing a cracked plastic bumper cover. Most of the work is done from the back side using JB Weld structural plastic adhesive and fiberglass drywall seam tape. There are two holes that need to be filled. I used the JB Weld structural plastic adhesive as a filler but am concerned the primer and paint won’t stick to it. I am thinking of cutting it out, backing the hole with the fiberglass tape, and filling the holes with Bondo Bumper Repair Kit, 00280, .34 fl oz. What are your thoughts?

I am not familiar with this product from JB but I seem to recall their standard epoxy that has been around forever is paintable.

If you are talking about this, it is paintable. Make sure you aren’t bonding to one of the incompatible plastics listed or it will just peel right off.

I am not sure about this one. There is no mention of it being paintable.

It is always better to use the product specifically designed to do the task… Use the Bondo Bumper Repair kit.


I have a feeling this thing is never going to look real good so just try to prime and paint the repair . If it does not work then do something else.

I’ve used the JB Weld, straight w/o filler on very small areas and it is paintable but it does tend to sag and because it’s harder than the filler mix, more difficult to sand smooth.

I’d suggest trying the Bondo product first.

So Bondo it is. I will cut out the JB and start over. Not the answer I wanted but it is the right process for the long run.

If you had paid attention to the earlier comments on your post to use special bumper cover filler, you would have used the Bondo product to start.


Both are paintable but depends on where you’re using it.
I suspect the straight JB plasctic, with possible fiberglass mat, makes a stronger bond so with a split and on the back just gloop it on.
On a visible area area, probably the Bondo.

Good luck and have fun.

He said in his original post that he had already used the JB weld and would cut it out and redo it if need be.

Make sure you use the correct paint for the bumper. it is different than the rest of the body paint.

He asked about this in an earlier post before he started the repair and a couple of us told him to use a filler specially made for bumper covers. But he used JB-Weld anyway and posted in this thread if he really should have done that.

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Yeah I dunno, paint for the bumper would just have a flex additive in it to prevent cracking. I don’t think you’d be able to get spray cans with it. I just used the standard mix on bumpers and never really had a problem. I’ve never priced the flex additive but after buying paint, hardener, fish eye, primer, sealer, clear, and reducer, never been in the mood to spend more. For me anyway not for sale so I’d just complain to myself.

All paint has flex additive in it (or doesn’t need it) now. I went through this a number of years ago when I repainted my '93 Saturn racecar after an accident. Base coat-clearcoat paint. Sprayed the same material on the bumper (urethane), fender (SMC) and the hood (steel).

There are a couple of online vendors that will sell you correct color and formulation in a spray can. Clearcoat, too.

Plastic bumper cover progress.

I used the JB Weld structural plastic adhesive because none of the recommended products were available and/or cost too much.

Multiple YouTube videos used this product and fiberglass cloth or nylon drywall seam tape to repair the plastic bumper cover from behind.

This JB Weld product is a paintable epoxy gap filler so used it to fill the two holes in the photos.

Using SEM flexible primer, U-Pol chroma base paint in an aerosol can that was custom made from the cars paint code, and finishing with U-Pol clear coat.

Hope this answers some questions and/or comments made here.

I couldn’t have done this job (was going to use fiberglass) without the help from this forum.


Looks nice. Sem is good stuff. I used their ready made bumper paint before and worked good. I’ve also used their vinyl paint. It can be ordered in a multitude of colors for interior use.