Self etching primer question
 

Hi

I have only used Self etching primer a couple times. My question is do I bondo first, then put the self etching primer on. Or do I spray the self etching primer on first then bondo over it. I think I should do the self etching first, but my paint supplier said to bondo first. He said bondo is made to stick to steel.

Thanks
Dean

dont use the self etch on anything but raw steel it wont stick well to the plastic fillers or other primers etc.. I would sand to metal, epoxy prime then rough areas for filler and fill. Self etch probably wont be needed.

check the p sheets when in doubt

Your paint supplier is correct. Rough up the surface first taking all the paint off. Bondo, sand smooth, then self etch. Or you can use a high build primer as Slick Sand and then no etching primer is needed.

Jim

This is the correct method! Most self-etch primers can be used over aluminum and galvanized as well. If your model year P-car has a galvanized body, great care should be taken not to break thru the galv if at all possible, just rough the exposed steel/galv area and use the self etch over that with as little overlap as possible onto surrouinding painted surfaces.

The self-etch that I use (PPG) specifically says to avoid using bondo under or directly over this primer, but instead to top coat it with epoxy 1st.

Bondo itself is not moisture resistant, in fact it absorbs it. Even in simple humid conditions, placing bondo directly over bare steel will allow rust to start; that's where the bondo-blisters you see on many poorly refinished cars come from.

On galvanized car bodies; very few plain primers properly adhere to zinc, self-etch primer or a wash-off conversion coating are a must.

Dean: I used this product on a 912 that I took down to bare mental about 15 yrs ago.......My mistake was, that I waited a few weeks to paint over the primer. I never got a good bond and you could take your fingernail and scrap the paint off the primer. I was told that I should have applied the top coat within 24 hrs.......

Things might have change, but be sure to check this out with your paint supplier.......g'luck....

This project is non galvi steel. I used to use a wipe on product on bare steel. I liked it cause I didn't have to clean the gun.

Thanks for the response.
Dean

The acid in the self etch can actually eat the filler. Don't use on anyhing other than raw steel.
2X primer .. then body-work ... then sealer... then base .. then clear... is the correct process these days.