Better Beaters - Building Cars and Daily Drivers

 Glue-O-Rama! 

Take your choice!

If you're talking about plastic, the subject of glue can't be too far away. You know that those plastic bits are eventually going to break!

So many types of plastics, so many adhesives that just won't stick. The hope is to find something that will.

There are the old standbys:

Super Glue from a whole different bunch of manufacturers.

JB Weld.

E6000 (or any clear silicone )

There are quite a few two part epoxies, glues, and fillers. They are strong, but will they stick to the base material?

There are spray adhesives for fabrics and vinyls.

Oftentimes a splint can be made to help hold the two broken parts together, I like to use aluminum flashing, it can be easily cut and formed, with basic hand tools. Then it can be attached by small screws or pop rivets. 

I'm not a big believer in duct tape, but there are times when it can be suitable to the job. 

3M double sided tape can be a quick and effective fix. 

There are special plastic bumper adhesives.

All of these repairs call for a lot of ingenuity. It helps to have several of these adhesives on hand. Usually you've disassembled something, find broken mounting tabs or pegs, and you need to fix it right away so that you can reassemble the components. 

A typical piece of plastic,

I decided to do a test of some of the commonly used adhesives to see if they would work on an automotive plastic panel. I chose the damaged front license plate mount that I replaced on my Navigator. This is a tough plastic part, somewhat flexible but quite strong. I think that it is made of PVC and it seems typical of plastic parts found  in the cars interior. 

The waiting test subjects.

I used a hacksaw to cut several bits of plastic from the edge of the piece. The test will be to see which adhesive will hold it to the parent piece. 

There are four candidates. 

I had this sitting around.

#1 is a glue used to join PVC lawn irrigation pipes. It's a two part process, first a primer is applied. After that dries, the glue is applied to both parts. I thought that the pipe material would be similar to the plate mount.

The best super glue that I've found.

#2 is Loctite Super Glue. I have found this to be one of the best of this type. It also comes in an easy to  control  squeeze bottle. My first impression was that this probably wouldn't stick very well.

 

#3 is JB Quick Weld. JB Weld is a known quantity and is quite versatile for repairs. Usually to rigid surfaces.

This one surprised me.

#4 is E 6000. This is a flexible silicon caulk-like adhesive used by many crafters. Both my Wife and Daughter use it when making jewelry and other assemblages. 

May the best glue win!

Surface prep consisted of wiping down all surfaces with rubbing alcohol. I did not roughen up the surface to provide a better bite. This might have affected one of the adhesives more than the others. (Looking back, roughing up the surface should have been a part of the prep for any adhesive.) 

The PVC pipe glue had been sitting in my garage cabinet for a very long time, possibly twenty years! The primer seemed fine, the glue was a bit gelatinous and might have been past it's prime. It was still very aromatic. The primer seemed to melt the surface of the plastic a bit. After I applied the glue, it didn't seem to set up at all.

The Super Glue was easy to apply, I may have applied a bit too much and it took longer to set than I expected. 

I mixed up the JB Weld right on the test surface, I also probably applied too much material as it took longer to set. 

Finally I applied the E6000. I didn't have a very high expectation for it's success. The application area was pretty big so I thought that it would probably hold, but maybe not as strong as I would like. 

The Super Glue set up the quickest. It felt quite secure. The PVC pipe glue didn't set up or hold at all. The JB Weld began to set after about ten minutes, the E 6000 after about 20 minutes. I decided to let the JB Weld set for another half hour. The bond seemed pretty strong.

I tested the bond by twisting the glued piece back and forth. I didn't go crazy, as this wasn't a destruction test.

The E6000 stated that it would need 24 hours to cure fully. I left all of the samples sit over night.

The Super Glue was very impressive. I've had experiences where Super Glue won't even dry on certain plastics. It felt as tight as it had felt the night before.

The J B Weld stuck to the test piece pretty well.

The JB Weld seemed pretty tight, but as I twisted it harder it broke loose. It might have held better if the surfaces had been roughed up before application. However it did stick to the little piece as it broke free. The E6000 really surprised me, it seemed to be holding as well as the Super Glue. It finally broke free after more vigorous twisting.

It appears that Super Glue could bond broken edges, this wouldn't be a very big surface area and it might fail under stress. The joint could be built up by sprinkling baking soda on the joined area. That could be repeated until the desired thickness was achieved. It seems that JB Weld might be used in the same way to reinforce the broken edges. JB Weld is a liquid epoxy that is very hard and strong when it dries. 

I don't know if the E6000 would be as effective in joining two broken edges, however if the break could be backed up by some type of material, say, fiberglass cloth, it might form a strong flexible repair. My test was joining a flat piece of plastic to another flat surface, this provided a very large area for adhesion. 

If fiberglass cloth was used as a backing material, POR 15 paint might also be an effective adhesive. Especially as the cloth could be saturated with the POR 15, and that stuff sticks to everything! The entire repair would be tough and flexible. This could be a real plus when repairing a somewhat flexible panel. This is the type of repair that is recommended by the manufacturers of POR 15. Weathered plastic panels, or old hard board panels can be given several coats of the paint. It will form a tough plastic skin. Voids in rusted metal are bridged by the saturated fiberglass cloth. Several successive coats increase the strength. 

I've used the POR paint and the epoxy for repairs. That stuff is very tough.

I'm going to do further experimenting with POR 15 in a future post; Glue- A- Rama Part Two.