Acrylic Enamel over Lacquer?

[markeb01]

I've spent a few hours researching the archives and could still use some help.

I painted my 60 GMC stepside with black PPG acrylic lacquer about 10 years ago over the well sanded original paint. This was my daily driver for years and the finish has deteriorated and is badly chipped needing a repaint. This is a hobby car that (now) sits in the garage most of the time protected from the elements. I realize the best plan would be to strip everything and start over with urethane, but I’m retired with back and knee problems and I’m just not up for disassembling the entire truck again to get all the lacquer off.

I’d like to sand off most of the easily accessed paint and spray the exterior and jambs with single stage hardened acrylic enamel (black again) to avoid the rub out process of another lacquer job.

Question –is there any 2k primer surfacer that can be used over the lacquer where the chips require repair. I don’t want to ever use lacquer primer again due to the shrinkage, gassing, etc. In the jambs where the paint is good, does it seem likely catalyzed acrylic enamel could be sprayed directly over the existing finish, or would it also tend to lift the lacquer.

If my only option is to do a complete repaint with lacquer, is there any 2k primer I can use to avoid using lacquer primer.

Thanks.

[barthmonster]

I'm no expert, but in the jambs you should be okay the lacquer is cured. Remember, back in the day enamel always went over the top of lacquer (lacquer primer) and it was fine, except for the shrinkage that you already mentioned.

I feel for you with the knees and back. These chips will need feathered out, then filled with primer or glazing putty. The first primer that comes to mind is a polyester-primer, they don't have shrinkage. It's really a sprayable bondo, and some are rated to go on bare-metal. Clausen's All-U-Need is supposed to be pretty good...

http://www.smartshoppersinc.com/Auto...en_Primer.html

If you have a suitable mask, I'd urge you to consider a Urethane product of some kind, they're much more durable...
Kirker is $48 a gallon...

http://www.smartshoppersinc.com/kirk...urethanes.html

Good Luck !! Hope this helps a little

[recoatlift]

if i recall correctly the old adage, 'you can put enamel over lacquer, but you can't put lacquer over enamel.'

[Phil V]

The problem with spraying anything over lacquer (paint or primer) is that the thinners/reducers from the paint/primer sprayed over the lacquer will be partially absorbed by the lacquer. The lacquer will slowly off gas those thinners/reducers while a catalyzed paint sprayed over that lacquer will fully chemically harden (trapping the off gassing thinner/reducer at the top of the lacquer paint/primer and under the new catalyzed paint. This CAN cause a serious delamination problem where the catalyzed paint will come off in sheets or large chips very easily. Any type of lacquer (paint or primer) is a very poor foundation for anything sprayed over it (other than more lacquer).

I have stripped whole cars with razor blade and blow gun in a couple hours that were painted with hardened acrylic enamel over lacquer primer. That same scenario would apply to urethane paint sprayed over lacquer primer (or lacquer paint).

[markeb01]

Thanks for the input and the weblinks. For the price it seems worth experimenting with the Clausen/Kirker products. As expected there's no easy answer with the existing lacquer finish.

Phil you've convinced me anything catalyzed over the lacquer is a bad idea. I may just touch up the jambs with more lacquer or air dried enamel, then strip all the surface sheetmetal and start over. I'd rather do more work now than to have to do it twice. Thanks again.

[recoatlift]

my major concern is what's underneath? lacquer primer over bare steel scares the begeezeus outta me. that would be a major weak link....adhesion probs.
in your case [age, aches,& pains...hey, i'm 64] i understand the work load.
i'd feather the chips & imperfections, spray can etch my bare spots [ i really prefer loading my gun with etch...film build.] but the rattle can is better than nothing. they also make dtm [direct to metal] primer in a spray can. now you can spray a 2k primer surfacer over the vehicle. please note i never spray 2k primer over bare steel. finish sanding in 600 or finer, tack off & then go directly to color. no need for a sealer as the 2k sanded surfacer is an excellent sealer in itself. tack the base every time. spray color to hiding. proper flash time & now clear.

[Len]

Enamel over lacquer is ok as long as you're not looking for a "first class" finish. Lacquer primer OR paint is a poor foundation for anything. Urethane over lacquer can be a disaster because the urethane tends to melt the lacquer and if you're going to use urethane I'd recommend removing the lacquer.