I'm currently working on repairing some areas on the underside of my '67. Everything was sandblasted and some patches were put in. I have USC duraglass I want to use to smooth out some weld seams, now should I prime with my etching primer first, and then put the filler in, or should I put the filler in first?

Thank,
Steve

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MY PROJECTS
1967 Chevelle SS396 - Currently under construction

1970 Camaro RS Z28-
Currently thinking about it

Filler first, then primer.

Prime first. The Metal etch has an acid that open the pores in the metal to give it better bite. The acid can lift the filler. If you fill first, keep the primer away from the filler as much as possible.

Filler first, then prime.

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70' El Camino SS 396 in pieces! Astro blue, black stripes someday.

Epoxy primer first, then filler.

Steve, you can do it either way. I would recommend,(in this situation), that you do the filler work first then prime and paint. Here's why:

Assuming from your post that all your doing is filling in weld seams of patch repairs on the bottom of the floor pans. Complete all filler work, then etch prime, followed with epoxy primer and final paint,(I recommend single stage urethane on floor pans) and your done on the bottom. If you follow the paint manufacture recommendations on application times you can avoid sanding between coats, (it's wet on wet application), this will save a lot of elbow grease and you will have a first class and very durable finish.

By doing the primer work first then doing the filler work, you could bust the time constraints for wet on wet application causing yourself to go back and scuff the primer to ensure good adhesion. Sanding all those nooks and crannies ain't a lot of fun. Hope this helps with your decision.

Rob

Paint first, then prime, then filler, finally clear coat http://www.chevelles.com/forum/tongue.gif.

BOD

Follow the directions on the P-Sheets (Product data sheets). Some metal etch primers should not be sprayed over filler or painted surface. The acid can weaken the paint and filler. This is why I metal etch, then GLAZING PUTTY filler followed by sanding primer. Glazing putty can be applied to scuffed painted surfaces.


What brand of metal ecth are you using?

BEFORE YOU USE FILLER, READ THE P-SHEETS
Just make sure it can be applied over filler.

<BLOCKQUOTE>quote:</font><HR>Originally posted by AlMyPal39:
What brand of metal ecth are you using?
<HR></BLOCKQUOTE>


DuPont Variprime. And 66Rat made an excellent point, I don't want to have to sand the whole underside if I miss the window for the next step, so I hope I can use my Variprime over the Duraglass!

Just on the safe side, call up DuPont or check the P-Sheet. Better safe than sorry.

<BLOCKQUOTE>quote:</font><HR>Originally posted by AlMyPal39:
Prime first. The Metal etch has an acid that open the pores in the metal to give it better bite. The acid can lift the filler. If you fill first, keep the primer away from the filler as much as possible.<HR></BLOCKQUOTE>

No "pores" get opened, what most metal preps do is leave a phosphorus acid coating on the surface. This is NOT what you want under a polyester putty or filler. If you go to the P sheets on the filler you will not see as a "suitable substraight" acid containing products of any kind. You will see BARE metal or epoxy primer.



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1965 Buick Gran Sport Convertible
1965 Buick Skylark H/T
"Fan of most anything that moves human beings"

By the way some etching primers have a recommendation to spray OVER polyester fillers (bondo). Sherwin Williams for instance says "over properly cured polyester filler" that would be 12 hours old min.

I have did my filler work then etch primed, then urethane primed for years. But I am leaning towards the epoxy prime then filler then urethane, it just sounds like a great way to go.

But, under the car, I would go with filler then etch, then epoxy for all the reasons 66RAT said.

My next project here at home I will do that, at work, I do as the shop does. That would be filler, then a iso free 2k. I don't like it but that's what they do.

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1965 Buick Gran Sport Convertible
1965 Buick Skylark H/T
"Fan of most anything that moves human beings"



[This message has been edited by MARTINSR (edited 07-22-2001).]

Thanks MARTINSR, for clearing it up. The PPG metal etch I used said to avoid spraying on filler. I use the metal etch first, then DP epoxy primer and then filler followed by sanding primer, sealer and finally paint.