Seam Sealer and POR-15 - which first?

[ktm]

I am in the process of removing the undercoating from my rear wheel well. I am encountering the factory seam sealer at the fender/body seam. I plan on applying POR-15 in the wheel well once finished.

I know I need to replace the seam sealer, but I am concerned that the POR-15 will not adhere to it. Conversely, I am concerned that the seam sealer will not adhere to the POR-15 if I were to do the reverse.

Any suggestions?

Thank you,

Bo

[JLPurcell]

Talk to you local paint supplier. Unless something has changed you should use the seam sealer then the POR-15. The seam sealer is designed to have such material adhere to it. I have not painted a car for a few years so check with your supplier. Dupont puts out educational videos on use of their products. jlp

[EScanlon]

One of the main problems with Seam Sealer is that if there is any moisture caught between the metal, then you'll have corked it in place....and you'll get rust.

POR has a product call POR Patch, which is basically thickened POR and comes out of a tube. You could use this first and then paint POR over it, or you could do the POR paint first then the Patch (that's what I did). In either case, the POR is in contact with the metal and will absorb/react with the moisture in the seam.

You can still use Seam Sealer afterwards or even undercoating.

There's been some talk about Zero Rust, but I'm not familiar with it. Maybe someone could toss in their experience with it. After all, the Preservation part of the club encourages that we find the BEST method of rust-prevention.

So, anyone out there want to chime in on Zero Rust?

Enrique

[ktm]

I have some POR patch in the drawer. Thank you for the recommendation.

[jmortensen]

I would pull the sealer out of the seam and see if there is any rust in there. In my car the seam was pretty rusty. I used a pick and a wire wheel to remove the sealer from inside the fenderwell and inside the cabin (inside the cabin is a real PITA by the way) then sprayed a rust neutralizer, PickleX 20 in the seam. Then I stitch welded the two together. Next for me is going to be several coats of very thinned Zero Rust, and then I haven't decided whether I want to do seam sealer again or not. Seems like everywhere the sealer was rust wasn't too far behind...

[JimmyZ]

Applying seam sealer to bare metal is not good practice. This doesn't stop lots of shops from doing it though. If you want the repairs/car to remain rust free then paint first. You can always take a scotch-brite and scuff the notch before applying sealer if there may be an adherence question.

If it were me I'd clean and treat the metal then epoxy prime. Sealer goes over the primer which in turn gives some protection in the event of a crack in the sealer. Follow with some color then apply shutz. (3M product) Applying shutz reqires a shutz gun and a can of shtuz totaling $60. It would then look authentic. I beleive that when I striiped my fenderwells this was what I found they had done at the factory

POR is extremely tough stuff but make sure that you apply it thick enough. Make sure that the metal is well prepped and NO moisture is in your lines etc when applying it.

MHO

Jim

[a7dz]

I just completed the bottom of my car. I did strip the seam sealer sand blasted the complete wheel wells prepped the surfaces per manufactures spec's. (Degreased and etched) I used the POR patch as my seam sealer then painted POR 15 over it. Yes I did take a little disc grinder and smooth out some roughness in the POR patch and you can not tell it is there. I did both sides of the seams as best as I could reach them and completely satisfied with the end result.