Epoxy Primer

[Hoosier Bird]

Ok guys, I've been working feverishly on the 57 driveline getting it detailed. I've stripped all the front end components, sand blasted them, rebuilt them, epoxy primed them, and then painted them with acrylic enamel with hardener. I stripped the rear end, bought new springs and basically did all the same things to this. Took everything down to bare metal, replaced all seals etc.......Now here is my question. I've been watching a couple of restore jobs being done on YouTube. It seems they strip most everything off of the car, replace the metal that needs replaced and then epoxy prime. The weird thing is that they epoxy prime over some areas with some surface rust. Not flakey surface rust but just a slight amount of surface rust. Is this kosher? Will the epoxy primer not let the rust get any worse, ever? Just curious.

 

[Big John]

I've used some of the rust paints like POR-15 with real good luck. Those are made for painting over rust and it encapsulates the rust so it can't start rusting again.

I don't know about epoxy primer though. I would think that you need to get all the rust off first.

 

[droptop]

Why take a chance of it coming through you new paint in a couple of months? Get the rust off before putting on any paint.

 

[Hoosier Bird]

The spots that they were priming were the frames under the quarters and areas like that. They could be sand blasted clean but that's about the only way.

 

[69runner]

Products like POR-15 have chemicals in them that convert the rust into another compound that is no longer rust (and you can paint over it). There are limits though. If the rust is too heavy, the treatment won't go deep enough and the rust underneath will keep working and show up again later. These products certainly have their place in the restoration process. Epoxy primers have none of these chemicals in them and have no effect on rust. A good epoxy primer has etching compounds in it to prepare the clean bare metal so the primer can adhere to it. The bottom line is that if you are going to prime an area, the rust needs to be treated to make it something else or the rust needs to be completely gone before you prime. Nothing will adhere to rust. The latter is by far the best if possible.