Depends where it is. Most sheet metal I cut out and weld in patch panels. For areas that aren't easily accessible, POR-15 is my go to product. Brush it on nice and thick.
I've been searching and watching rust prevention reviews for a few days, when it's time to blast my frame, people opinions are everywhere. Tops are Epoxy prime & paint, KBS seal & por 15 & maybe similar Eastwood products. Think I'm leaning towards KBS,same as por, a bit more affordable and they come in different colors.
When my build was at that point, everyone was talking about/recommending por-15, so that's the way I went and never had a reason to even try others. Brushing is just fine for it, as it takes 4 hours to fully set up in "normal" conditions (lower humidity), so all the brush marks flow out and will end up like a sprayed finish. Also, you want to make sure you get extra material brushed on in seam areas as it will seep down into the seams for added protection. You can't do that too easily with a spray. I strongly recommend buying lots of smaller cans because once you open the can, it's got a short shelf life. I used a glass jar with a smaller neck so you can wipe off excess from the brush without getting it on the threads for the lid. Make sure the lid and can are perfectly clean before you close it up, and use a piece of saran wrap under the lid.
Would killing the rust first, be better than encapsulating it? I used the cheap concrete etch from Home Depot. It makes rust a black color. After that you can wire brush it down and do it again for sport, then encapsulate. I have seen some things encapsulated only to keep eating itself away and only the encapsulator is left hold rust together.
. Do you need to wash that concrete etcher off first, before painting or applying any type of encapsulator?
From what I have read some people leave it on, check the videos on youtube, some good some not so good. but it turns the rust to black iron oxide or something like that, here is thread on it https://www.jalopyjournal.com/forum/threads/surface-rust.1197695/ similar to the OSPHO metal prep, I would wash it off but use self etching primer over that area to prep it. Also you need to be aware of the concrete or the floor and other metals you dont want etched.
I used 3-4 coats of Eastwoods Rust Encapsulator. Not cheap stuff. 3 years later, the rust is no longer, um, encapsulated. Rust spots creeping up thru product. Would not recommend.
Also if you have new patch panels make sure to clean the metal and maybe etch it and use a etching primer. Otherwise there will be no grit on new steel for the POR-15 to stick to. Just use a good primer over new steel.
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