When to Add Body Filler and Metal Filler????

[RTR]

I have had a few peices sandblasted an they are ready for the primer. A couple peices need some body filler to smooth out and I am going to use some JB weld on the rims to fill in some pitting.

My question is......should I prime all peices first then do the body filler or should I do he body filler before I prime. ?? What is the common practice for that?
 

[davediehl@hotmail.com]

Always fill using clean metal.
 

[CNKS]

I apply it to bare metal. Others put it over epoxy primer if they think rust will form before they are done, they then apply epoxy over the body filler. In any event put it only over epoxy primer or bare metal. Epoxy is the ONLY waterproof primer. In my opinion it will adhere better on bare metal, that is what the instructions say to do on the can or spec sheet.
 

[Stephen Newell]

I like to epoxy prime first and then use body filler.
 

[Jason S.]

You will get 100 answers on that one. Everybody has their opinion on that. I never fill over bare metal. I rough it up good but I never exposed the bare metal because then it is exposed to moisture and then you fill over top of it. Did you ever read a can of Z Chrome body filler? It's made by Clausen the same people that make Rust Defender primer. It said right on the can they recommended heating the metal before applying filler to eliminate moisture. I watched a program on a shop out west that builds street rods and customs. Do they go to bare metal? Nope. They use a red scotch brite to rough the primer up and fill over that. Personally I wouldn't do that. I prefer a piece of 80 to 120 grit myself. I can say in 20 years of doing it I have never had any crack out on any cars or trucks I've done.
 

[B-maniac]

There's a couple reasonsfor priming first. One is that filler has zero corrosian resistance and the other is if you are filling over a pitted sandblasted surface , you probably will never get the filler to completely penetrate into those minute pits completely which will leave a small void to start rusting. Primer will penetrate and seal all the pits. Overkill??? Maybe , depends on your weather conditions , shop conditions and how long you plan to keep the tractor and intended use. A coat of epoxy will in no way impede the adhesion of body filler. It's just long term insurance. Your call. RB
 

[CNKS]

B-I'm not disagreeing with you as you have a good point. But, I use body filler to fill pits in bare metal. I sand everything off and leave the body filler in the pits. One of my tractors had that done 8 years ago, with no sign of any paint lifting. I also think that epoxy will seal the area underneath and it's not going to rust anyway. The tractors are inside in a dry climate. I have never used epoxy first on anything. My point is that as long as epoxy is used it makes no difference whether it is above or below the body filler. It could make a difference if another type of primer is used, as far as I know none but epoxy is waterproof. The above is presented without proof. But sometimes I think that everyone concerned about rust, except me, live in a swamp--just a slight exaggeration.
 

[showcrop]

[CNKS]

"Is it possible for metal in the bottom of a pit to be clean?"
It is if treated with Picklex or a similar product.
 

[B-maniac]

CNKS, I too have done it both ways and never a problem either way. That's why I mentioned the word "overkill" and climate conditions. I not only don't have moisture/condensation problems but when I use filler I apply a very thin first coat and squeeze it back and forth in all directions before building up. It's hard to assume everyone asking for advice on here has done this stuff as often as you and I and others so they may want to go the extra step.
 

[GordoSD]

Why would you use JBWeld on the rims? Bad idea. If you are filling pits the filler will be fine. If you have "holes" in the rims then you better start welding.
If you use JBWeld it will be near impossible to get them sanded smooth.
 

[CNKS]

JB Weld has its place. I use it for the deep pits on the "battery under seat" tractors that have had battery leakage, I don't trust body filler for pits that deep. It takes a LOT of sanding. I then cover the scratches with body filler -- it comes out ok.
 

[GordoSD]

The platform or the box?. Should never be pits that deep on tin.
My guru body man, 50 years in business and startes with lead, swears you can us the filler as deep as you want on"non flexing parts". Wheels would qualify as would platforms. trust me and try one. Save you lots of work.
Or you could break out the torch and the lead sticks and steel paddle
 

[CNKS]

The platform, either way will probably work, but I have now been working on my Super M for more than a year, another half day doesn't matter much.