Ok, ANOTHER thread with ANOTHER question...


After reading some of the restoration threads, I am concerned I may have done some things wrong. I had watched a few You Tube videos where guys would get the car to bare metal, then would treat for rust or fix a panel (in my case weld up holes), the apply body filler directly to the metal after sanding with 80 grit for adhesion. Then came etching primer and fill primer. This is the method I have been using.


However, I have been reading recently where you work the metal, apply primer first, then apply body filler on top of the primer. Then use more primer then block sand, etc...


Comments please? I still have a lot of prep to do, but am at a point now that if I have to redo something, now is the time!


Thanks!
Bill

 

There are different types of body filler which are formulated to be applied over bare metal or paint / primer. When I painted my 71 98 I used at least 3 different types of filler:

Fiberglass filler:


Metal Filler:


Glazing putty:


I wish I could give you more direction; however, I painted my 71 98 by taking an auto body course at a local vo-tech. The instructor was truly a master craftsman and guided me in purchasing supplies and applying it.

 

I was always taught that Bondo goes over clean bare metal, but it does not surprise me that with the newer formulations of filler and paint, some can go over primer, too.

- Eric

 

Most fillers are fine on bare metal but modern fillers have become really good over time and will stick to 80 grit prepped paint. At work I still do my fill areas bare metal but feather the filler into the paint.

 

I'm old school, so it was always filler on bare metal. If you want the extra protection, and perhaps extra adhesion, you can put fillers over epoxy primer. I would not do it over any other primer, esp. an etch primer. You can have problems with the acid reacting with the hardener in the filler. Putting etch over filler is probably OK, but I can't personally recommend it.

 

FWIW - My MatrixPaint supplier recommends filler over primer but not etching primer.

 

Thanks for the replies! I will continue the way I have been doing it then.


Bill

 

Body filler can/should be applied over a cured epoxy.
I'm sure many of us working on old body work when grinding off old filler found surface rust under the filler. The point is filler does not seal out moisture and in many cases absorbs it. The epoxy is there for corrosion protection only.
If entertaining this method there are right and wrong ways to do it and right and wrong fillers and epoxies to be used.

Do it correctly it will last the life of the repair

NEVER apply any fillers/putty's over an etch primer. It will soften the filler and never setup