My 55 f100 has some surface rust that I want to deal with and then protect with epoxy primer before I move on to actual body work. What process do you guys recommend?

 

Scuff it down with as coarse of grit as necessary. Finish up fairly coarse like 180-220. If it is pitted put some metal etch in a spray bottle and scrub it with a brush. Use a stainless wire brush if necessary. Epoxy it and you are good. Good epoxy primer doesn't really need an etch but the rust has to be gone. I have 20 yr old paint jobs running around with no rust returning using this method. Other ways to do it no doubt but this is mine. Huge areas of bad rust and I am sandblasting if at all possible.

 

I can’t help with the rust, but epoxy before body work seems backwards to me. If you do any bondo over primer it will map, meaning show the outline of the bondo.

 

It depends where you are and how long it takes to do bodywork. In a perfect environment we would do it all shiny metal and then fill and prime. But in a cold, wet climate like here compromises need to be made.

 

Bondo over the epoxy is the way several body people and forums have told me to do it. Works great. Strip the paint to metal. Do some hammer and dolly work or welding if you have time. Prep the metal using a metal etch, them primer. then there is no fear of surface rusting. When ready for bondo, a sand with 180 and you are good to go with bondo. Once done with it you can epoxy over it or use a 2K primer. You will sand through some original epoxy buy that is OK. The way I was taught anyway, FWIW

 

Decades ago, when body filler had names like "Black Magic", filler had a bad reputation for not bonding to the prepared metal surface and for being somewhat porous. The combination of the poor bond and the porosity of the filler lead to rust formation between the filler and the metal. To compensate, bare metal was primed prior to the application of filler. So here we are in 2021...body fillers have superior bonding and are not porous. Manufacturers recommend the application of their fillers over bare, clean metal to assure maximum bonding/adhesion. Bottom line...either technique works, just understand how we got here and you will be way ahead of the game.

 

My actual intent is to stop or eliminate the rust, while preventing new rust from forming by applying the epoxy primer. When I get to the body work phase, I intend to remove the primer in the areas I'm repairing and then repriming after the work is complete. Just my thoughts until someone says there is a better way. Any comments or concerns are welcome.

Patrick

 

We all go through the same mental gymnastics you are working through. You want to get the metal clean and sealed but it will take a while to do all of the body work. Just a heads up, epoxy primer can be a real pain to sand off so you may want to explore the best combo of epoxy and filler that can go over the epoxy. Best of luck!

 

I’m no expert, I’m just repeating what I was told. I could be wrong.

 

Yes we do. When you have clean bare metal you seal it. Bondo sticks to epoxy primer just fine. I want the bondo sealed on both sides. It is draws water it causes more problems than any other body repair product I am aware of. I have seen it fail to adhere to epoxy primer zero times, even after decades. Once your clean metal is sealed you can work on it for years if necessary, You'll be scuffing it down and resealing it before you paint anyway.

 

Thanks for the advice, I will put it to good use!!