Ihavethisname

I have already stripped my 77 down once to a layer of maroon paint,used one shot PPG acrylic primer and several coats of Midnight black lacquer. All was fine until I took it outside in the sun and lots of blisters popped up. After sanding the paint off again in one of the bad areas I noticed that the blisters kept on going until I got down through another 5 or so layers of paint until I got to a greyish white layer with a marbled finish. Is this the SMC layer? I have now sanded all the paint from the car, leaving only this marbled finish. Do I now apply an epoxy primer as the first coat or two, then acrylic lacquer primer/filler,guide coated and sanded to 600 dry, seal with epoxy primer/sealer and then 4 to 5 coats of acrylic lacquer? Will the epoxy primer solve the blister problem provided I don't add any moisture through my airline and spray when relative humidity is too high? Sorry for long winded post, any input from the experts would be great!

Scott Marzahl

Sounds like solvent pops, your acrylic probably didn't seal the old paint. It was best to start with a clean body. Make sure that SMC body is wiped down real good with Acetone several times. Make sure it airs for a couple hours. Then you need a couple wet coats of epoxy primer on it and let it set up for a few days. Next I'd use a high build polyester primer, something like slicksand. Block that and if you break through to the SMC, shoot the area with epoxy again. Depending upon your top coat you may be able to shoot on top of your high build, many do say they are top coat compatible. However, its often best to seal with a coat of epoxy reduced as a sealer and then top coat the next day. You need to check with your paint manufactuer if lacquer is a compatible top coat.

zwede

On my '71 we shot PPG K-36 (Urethane high-build primer) directly on the bare fiberglass. Worked just fine.

Ihavethisname

What concerns me is that how will I ever know that there is nothing in the SMC substrate that will rear its ugly head at a later date. What I've picked up from the forum is that it is best to seal in the gremlins with an epoxy primer and shoot your primer/filler on this before the 7 day window expires. Block sand to perfection and seal with reduced epoxy primer.Dont sand this layer but shoot on colour,in my case several coats of lacquer,colour sand between coats finishing with 2000 wet.Finally rub out with suitable hand glaze. I've stripped the paint off twice now and if I have to do it again I'm going to light a fire under it!

porchdog

epoxy is the only thing that will seal the old paint down other than a polyester primer . urethane primer is just for surfacing . it has little to no sealing qualities. lacquer primer is useless .
80 grit it down good , 2 coats of epoxy , then primer and block before last coat of epoxy. personally i see no reason to sandwich primer between epoxy. i just use epoxy.

crazywelder

Okay for fiberglass, but several brands of 2k primers (K36 for example) are not compatible over SMC without an adhesion promoter, so check the tech sheets first.

I would not sand between coats with acrylic lacquer. If you use the correct temperature thinner it should flow nice. Sanding between coats just opens up an opportunity for surface contamination. Especially with lacquer, once you start, keep going. There really isn't any need to sand between coats unless your gun isn't working properly.

In your original post, I think your blister problem is either surface contamination or not removing all of the wax and grease remover prior to painting. Solvent pop is caused by too much paint too quickly without enough flash time. Lacquer is more tolerant of paint builds and it will craze instead of bubble if you lay too much on too quickly.

With todays acrylic lacquer, the base color formulas go with or without a clear requirement. Does your formula require clear? Your paint store needs to tell you. If clear is not required, you will need more paint build than the 4 or 5 color coats that you originally stated to have enough film to sand and polish.

porchdog

mr hoover is right and do not use k36 under lacquer .

Ihavethisname

OK this is what I'm going to do. I'm going to put down two coats of PPG DP40 epoxy primer after cleaning thoroughly with wax/grease remover. Then two coats of PPG one shot lacquer primer/surfacer. Guide coat and sand this. Repeat primer and sanding sequence until surface is perfect. Now can I seal this with a thinned coat of DP40 epoxy primer or is this not necessary? Finally 5 to 8 layers of PPG AAA Midnight Black acrylic lacquer with no sanding between layers of colour. Will this work? My paint shop says I don't need clear with a solid colour like black.Will I need more than 8 coats of colour? Thanks so far guys, I think I'm getting there

crazywelder

Yes, that looks good. Use the reduced DP as a sealer before the black, it will eliminate sand scratch swelling with lacquer. I would go 8 to 10 coats of black if you want enough to polish. It all depends on how well it flows out so make sure you use the right temperature thinner.

What primer are you using? I would recommend PPG Kondar.

Ihavethisname

The primer is a PPG product called "One Shot Primer Filler" - CODE 289-45711. It is a high build lacquer primer ideally suited to topcoating with the AAA lacquer finish coat. I assume it's ok to sandwich the lacquer primer filler between the epoxy primer first coat and the reduced epoxy primer sealer coat or is this dubious?

porchdog

if using solvent based wax and grease remover be sure to let it dry well before you seal the glass .

crazywelder

PPG product codes begin with alpha characters, I can't find "One Shot." I'd like to see what it is.

Ihavethisname

These products are manufactured by PPG Industries in Australia so codes may differ from those in the States. The full description on the tin is " PPG Dulon One Shot Primer Filler 289-45711". I'm in New Zealand, those two little bits of volcanic outcrop in the South Pacific. I'm assuming PPG Australia and PPG USA are related.

crazywelder

Let's not assume, since we don't have PPG Dulon here in the states and the Ausie/NZ PPG web site defaults to North America when I select Automotive Refinish. Can you email the tech sheet to me? morechevys@sbcglobal.net

I am wondering what the product difference is between our Duracryl and your Dulon? Important to know before giving advice, especially after you had problems already.

crazywelder

Tony, Got your tech sheets and there are some minor differences between the U.S. Duracryl and your Dulon but nothing that would change advice.

The "One Shot" primer seems the same as the Kondar I recommended. Most notable difference between regions is the thinner and dry times. Apparently you only have one thinner choice, where we have 4 different thinners depending on ambient temperature range. Your thinner would be comparable to our mid temperature thinner.

Your tech sheet sheet says 2-3 minutes between color coats, I would give it 10 minutes. Your tech sheet also states 6 hours to overnight before polishing. I would give it 1 to 2 weeks before you wet sand and polish. If you polish lacquer too soon it will dull, wait longer for the thinner to escape and the shine will last.

Ihavethisname

Thanks for the advice Al. I'm a lot more confident about tackling this again.

58impala

Had any probs?

neat

Update?