POR-15 and existing paint

I have a couple minor spots with surface rust on my replacement frame. I got some POR-15 for some of the worse rust on other parts, and was going to touch the frame up but you’re not supposed to apply it over existing paint. Should I just mask and sand the spots to metal, POR and then paint? Am I going to have an “edge” that could peel if I don’t blend? IDK anything about paint.

 

See

 

In the background of the second picture you can kinda see my fuel tank skid, which needs a thorough cleaning and coating.

 

I think you are over thinking it. I use POR15 to spot paint skids, sliders etc. No problems.

Sand the loose rust the best you can. Rough up the paint where ever you are going to over paint. You just want to remove the gloss.

Clean oil and grease before painting. Mineral spirits is what I use. Let it evaporate/dry before painting. You can use methanol to clean the mineral spirits. Do not use rubbing alcohol. Too much water.

Paint, 2 light coats is good. POR should be top coated because its not UV resistant. I don’t top coat if its on the bottom of the truck.

My old IFS skid. Got touched up annually. Couple of times I just rattle canned it. Krylon and Rustolum both make a primer/top coat combo in a rattle can.

 

Por15 is really intended for painting rusty things. It doesn't offer any advantages for things that aren't rusty.

 

Just wire wheel those small spots down and rattle can. POR15 is like my last resort for a falling apart frame. Not an overall fan of the stuff and never understood the hype. It did work nice on some steel rims I had though.

 

It bonds to rust and is tough as hell, much stronger than regular paint, but works best on bare metal that has been cleaned of grease. Just scrape off the rusty spots and paint with POR. Not much UV hitting a frame so no need to topcoat.

 

If applying to bare metal, it needs an etching step to bond well

https://por15.com/products/metal-prep

 

Thanks for the replies. I’ve used POR-15 before on old cars, but on spots like a rusted trunk floor or a frame with 0 paint left. Never used it on a part that still has a factory finish. Probably overthinking it