Worth my time to POR 15 over paint?

[SeanH]

Hey guys,

I was reading the PDF at the link below, and it says at you can use POR 15 over paint, but the wording makes it sounds like that basically renders the POR15 innefective as it only functions when in contact with metal.

"CAN I APPLY POR-15 OVER OTHER PAINTS?

Yes, but you will lose the important benefits of POR-15. You must remember that ordinary paints are weakened by exposure to moisture. POR-15 can't stop rust if it isn't in direct contact with the base metal."

I'm not painting at this stage of the rebuild, but would still like to get some extra rust protection in the wheel wells. I was planning to POR 'em, but am now wondering if this isn't really worth it.

Your thoughts?

http://www.por15.com/Data%20Sheets/POR15ApplicationInfo.pdf

[john_a]

POR15 over paint is crap, it won't stick well to anything but your hands or rusty metal, and getting paint to stick on top of it sucks as well.

They sell a tie coat paint to go over the POR15 if you want to top coat with something else, but by then you've got a lot paint down that does not surface well, nothing you'd want to look at.

POR15 over paint or clean metal SEEMS like it goes on fine, but it does not make a strong chemical or mechanical bond to those substrates, and you are likely to see large chips later from small impacts. Fine for rusted areas you can't otherwise repair, but as a preventative measure it is not going to perform as well as a real paint system starting with an epoxy primer against cleaned & etched metal.

[robsanab]

i agree with john... have had success and failure with it on two different cars... seems to be very finicky stuff. When i tried over roughed up cleaned paint it did not stick... came up in strips.

had better success with ZeroRust in a can.

[bluedevils]

get eastwood rust encapsulator, works great over or under paint. As a principle, all rust fighting paint should be put over bare metal.