Anyone have issues bonding to Behr paint with adhesives?

[ramdough]

All,

I have a couple things I am gluing to a Behr painted truck.


I am gluing a flat glass panel using windshield adhesive.

I am gluing a fiberglass panel in using Sikaflex 252.

I am gluing a patch of steel (sealing a hole in an unweldable location) using 3M Urethane Seam Sealer, 08362.

Has anyone had trouble bonding to the Behr Marquis paint? Any prep advice?

Thanks!


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[osteo16]

id like to know also... hate to paint it all up and then the paint de-bonds where i put window caulking or something else....

 

[ToddJK]

An easy way to find out is paint a piece of scrap metal or something and put that adhesive on it. Try it on a regular painted surface and then some on a prepped (sanded,degreased). Adhere some type of plastic that you can grab and after it's fully cured, how hard is it to pull off and then you can see if the adhesive melted, bonded,ect, to that specific paint and if a prepped surface made much of a difference or not.

With so many different types of adhesives out there and different types of paint, testing is the only sure way to find out. That's what I do and one thing that works great are AR500 steel shooting targets. Shoot them with a 12 gauge birdshot and that will sand blast them clean everytime. Just wash the lead off when done before handling.

 

[Mullaney]

An easy way to find out is paint a piece of scrap metal or something and put that adhesive on it. Try it on a regular painted surface and then some on a prepped (sanded,degreased). Adhere some type of plastic that you can grab and after it's fully cured, how hard is it to pull off and then you can see if the adhesive melted, bonded,ect, to that specific paint and if a prepped surface made much of a difference or not.

With so many different types of adhesives out there and different types of paint, testing is the only sure way to find out. That's what I do and one thing that works great are AR500 steel shooting targets. Shoot them with a 12 gauge birdshot and that will sand blast them clean everytime. Just wash the lead off when done before handling.

.
The "Tape Test" works really well for adhesion testing... Blue painters tape shouldn't pull anything (paint) even if you burnish the tape to the painted surface in 24 hours. After a few days, full tilt 2 inch masking tape shouldn't pull paint - especially in full sun.

Adhesion Promoter will help.
Wiping down the surface to be painted with MEK or Acetone using a Lint Free Cloth will help remove any oil.

 

[87cr250r]

There shouldn't be any issues bonding to the Behr paint. The problem is that the Behr paint doesn't bond well to many automotive coatings such as epoxy primer. Any adhesive is only as good as the material it's stuck to. It's always best to adhere to bare metal when possible.

 

[Ray70]

So to elaborate on the bare metal a bit, the correct way to use Windshield Urethane is to strip the glue flange to bare steel, prime it with brush on windshield primer then use your urethane adhesive over that. The Urethane is also not really meant for raw glass either, the glass should be primed as well. Priming ( and masking the edge ) also makes a cleaner appearance if the adhesive can be seen through the glass on either side.
On the steel panel, I typically use SEM panel adhesive, which is a 2 part epoxy adhesive, but the 3M urethane seam sealer is probably similar, where the correct method both for strength and adhesion is to strip a 3/4" wide contact area of both panels to bare steel. Apply the panel adhesive to both parts and use a brush or plastic spreader to flatten the bead to a 3/4" wide strip that covers your entire bare metal area. Then clamp the parts together.
Now I realize this method is used for making structural joints, where as you are only trying to cover a hole by the sound, but like others mentioned, your adhesion will only be as good as that Behr has stuck to the substrate.