Last summer I cleaned the rust off of the trailer and painted it. Here is how I did it. Note: Amateur at best and no previous experience.
Scaled and wire brushed frame.
Painted with phosphoric acid
Wire brushed
Painted with Phosphoric acid again.
Painted with Rustoleum paint. Two coats.
Applied roofing sealer to undersides as undercoating.
It's only been a few months but so far so good.
I sent 30+ years in the business, and in my opinion, this is probably the best economical way of doing this job.
I would add, I prefer using the Valspar system, because they have an optional hardener. Even though it does complicate the application by
requiring personal protective equipment, (which you should be using anyway), it really helps with adhesion, and gloss retention.
The cost of using all quality automotive products can be so high, it is not usually worth it on something that takes a beating, like a trailer does.
The last time I did my flatbed 3 years ago, I used all high end automotive products, it took $600 to buy all the sand blasting media, sandpaper, 2 part glue, 2 part calk, 2 part etching primer, 2 part filler primer, basecoat, clearcoat, and vinyl stone shields. This is a 4x8 trailer, with a wood deck, and the deck was not included.
If you use low end automotive products, it will be cheaper. But my experience is that it really will not last any longer than the industrial enamel, (Rustoleum).
