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I sandblasted all of my panels on my 56 chevy. When I was done I put an etching primer on them because I knew it would be a long time before I got back to them to do the body work and I didn't want them to rust anymore. My question is can I put body filler right over the etching primer?

That is correct, however make sure the surface primer has enough bite for the filler to adhere to. Good luck with your project.

Tony

Be sure to store your rig indoors. The etch primer is porous and needs the final coat of 2k primer to be bullet proof.

Stuart

Tony When you say make sure it has enough bite do you mean rough up the primer with red 3-m pad or light sand paper?

Kevin:

Yes, that is correct, per the experts. I am restating what I have been told. Good luck.

Tony

Thanks for the help.

Kevin

kevint,

If you coat with etch primer, then sand through the primer (accidentally) when roughing for bondo, you are back to square one with no bare metal protection. I don't think you are suppose to apply etch primer OVER bondo.

If you etch prime, then coat with a 2k primer, your finish is solid, and you merely rough the 2k a tad for bondo...no sand through problems. You can then spot coat over your bondo with 2k again.

This is how I understand it.

Stuart

I was told in one post to never put filler over etching primer. They tell me it will not stick. I understand it is best to put down a layer of etching primer, then 2k primer, then the filler.
here is the post:
http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=4;t=003984;p=1#000005

Michael1964,

Good point! I did some additional reading on this topic, and it looks like you are right. I have been putting filler over etch primer, and all seems well, but I just might start coating the etch primer with 2k primer, and finish with filler over that.

Stuart

I worked as a heavy collision tech for several years and used my fair share of plastic fillers.I never put filler over primer, paint or anything other than bare metal. If you stop to think about it, plastic filler is only as strong as what it is bonded to. I have seen panels sustain collision damage that were repaired previously with filler bonded to metal, and the filler didn't even crack. I have seen panels with filler over paint get hit and the filler breaks or falls off the panel.I know body men who have done it both ways, but that is my experience with body filler.( my 2 cents worth)

I dont know of any paint manufactor that suggests you apply filler over etch primer. In fact the beroxide in the filler's hardner can react with the etch primer causing the filler to lose adhesion.

Another thing is that sandblasted metal might have more tooth then what the etch primer can fill. Meaning even after you spray your etch primer you can have some spots of bare metal exposed because the etch primer can not fill that tooth left from the sand. Most manufactors want alteast 180 grit prior to etch primer.

Personally I would scuff that etch primer with a red scuff and apply two good coats of epoxy primer over that etch. Epoxy has far better adhesion and corrosion protection then etch primer. Plus epoxy primer is NOT PORUS like that etch primer. Etch primer can absorb moisture throu it, epoxy primer will not.
Plus you can apply filler over epoxy primer with NO PROBLEMS. Many car manufactors like Mecerdes Benz, Lexus and Madza recommend filler to be applied over epoxy primer.

An epoxy primer that would work with that etch primer would be PPG's DPLF line. But before you buy any epoxy make sure it can be applied over an etch primer as some can not, but DPLF can...Eric

sevt_chevelle is correct epoxy is the only type of primer that you should use filler over. Most of them recommend the epoxy dry 24 hrs. before appling filler, also I scuff it before putting filler or primer over it if it has been on more than 3 or 4 days.