That is because it has not UV protection. If you use POR you need to clear coat it or top coat it with something else.

You should at least give it a scuff with 320 grit sandpaper.
Just giving it a wipe won't be enough surface prep for a good bond.
If cost is a concern and you do not want to apply a 2 part urethane which will have the uv protection you need, then a can of red Tremclad could just be the ticket.
Stay away from the clear based tints (for exact color match) if you go any other route, the paint will not cover.

Rustolium spray can will do the trick, I did mine over galvanize and has been fine.

thanks for the tip. Yeah cost is a factor so is time. I mean the trailer is a trailer in my opinion. its not rusty, just would like to make it look a little better and maybe some more paint to protect it from rusting.

I was thinking abou the can stuff, dont really have a logical way to get the boat off the trailer and dont want to spend a year masking the boat off.

can't beat rustleum, sand and go...great stuff, use the tall can that says professional, paint is better..

Por-15 do it right once... http://www.por15.com/WHITECOTE/productinfo/WCG/

bought mine today!!

+1

I did my old trailer a few years back. It was a dull gray, with some surface rust. Scuffed it, and used a small roller, and a brush for tight spots. Came out looking nice. Added some reflective DOT tape, and called it good....

[QUOTE=MILD THUNDER;3667676]+1

I did my old trailer a few years back. It was a dull gray, with some surface rust. Scuffed it, and used a small roller, and a brush for tight spots. Came out looking nice. Added some reflective DOT tape, and called it good....[/QUO

Same here , looked like new again ..

thats what Im going to do, thanks guys. Just waiting for the weather to get better.