E-mailed customer service. He stated that POR-15 is not UV resistant and clear coats will not work.
He stated that they have a line of pigmented second coat paint and the POR-15 should be covered with that.
I used Rust Bullit on a dune buggy chassis I just finished. It gets really good reviews.
What are you planning on the use of the por-15. It is not UV proof. I have found the best use of it is in door bottoms, trunk floors, rocker panels, ect. I clean up the rusty area as good as I can. Blow out any dirt or loose rust,scrape it, ect. Then I pour it in/on the area, use a foam brush or whatever works to get it into the tight areas. I then use a air hose and blow it into the cracks, under the flanges or brackets or anywhere I can not see. I like to see it run out. Remember to cover anywhere you do not want it. Including yourself. It does not come off after it dries. I use a rag to wipe off the excess where I do not want it. You can use laquer thinner to clean up before it dries. As to top coating it. It is very, very, hard after it dries. It is also very hard to scuff it. Inside trunks or bodies out of the sun it does not need much of a top coat. You can top coat with about anything, such as krylon or any other cheap paint. It would be good to use on a chassis and then top coat it with something that has the look you are wanting to achieve. In my opinion, it is a very good rust preventive in tight unseen areas.
I was going to use it on the chassis and axles. Parts that are exposed to UV.
I have over-coated POR-15 with most any outdoor metal paint with UV protection.
Restomotive Labs said to apply the over-coat just when you begin to feel a good drag with your finger/ before the POR gets completely dry. I have followed their instructions and it works well.
Just because, I would buy their top coat. It wasn't available when I was doing my top coating.
The topcoat is not a true black. It's more of a brown cast and will not keep its gloss. It is tough though.