[stone7777]

Sorry, I could not find a thread on this.

I plan on painting over an old lacquer paint job.

I really like the Summit Acrylic Urethane system.

Is there any issue going over the lacquer with a 2k Urethane Primer?

[Tim66]

I would prime it with a lacquer primer first, dust coat. Sand, Then go with dry coats first of urethane,sand and then wet coat.
The idea of putting on dry coats at first is so that the lacquer does not bleed through and lift.Good luck,Tim.

[paint guy]

I would never repaint over lacquer, and once I explain a common failure mode of lacquer finishes as they age, you'll understand why. Lacquer paints (for purposes of this discussion, it matters little if the lacquer is nitrocellulose or acrylic) will, upon aging, exude certain chemicals to their surface. These chemicals are commonly referred to as "plasticizers" and the process is referred to as plasticizer migration. The plasticizers are used in lacquers because resins commonly used to formulate lacquer paints are by nature, somewhat brittle. Consequently, as migration occurs, and it does in all lacquers, the films tend to become brittle ("short") over time, cracking and checking with age, and creating a couple of problems when recoated. The first could be that you end up with what is essentially a short, brittle lacquer "primer" base under a much more flexible topcoat. This is not a good situation for intercoat adhesion and expansion/ contraction of the differing paint films due to ambient temperature fluctuations. Also, even when overcoated, plasticizer migration will continue, and while this may not be as big of an issue migrating into and thru subsequent lacquer films, it would be detrimental to intercoat adhesion with a paint film of dissimilar chemistry. By definition, a lacquer dries by evaporation only, and as such, should be infinitely re-dissolvable with lacquer solvents. In other words, you should be able to literally "wipe off" your lacquer paint job with strong solvents and enough rags. Your Summit Acrylic urethane forms a film by (at least some) cross-linking, providing a much denser film, and this is one reason why any plasticizer trying to escape the lacquer may cause the urethane to lose adhesion. In short, I would remove all of the old lacquer, and re-prime with a high quality epoxy as a foundation. Good luck.

[stone7777]

Does the age of the paint matter.

Would the 30 year old paint be more stable (more time to dissolve)?

As you know stripping the door jambs, inner trunk lid etcetera.

Because I am only trying to buy 5 years until I can do a 100% full restoration. I was hoping to be able to paint without stripping everything.

My question is, will the paint lift?

[paint guy]

The age of the paint does matter. 30 year old lacquer could be getting short and start cracking if it hasn't already. If it has, do not paint over it. If your objective is 5 year longevity with a "scuff and shoot" and there is no cracking present, there is a good chance you could acheive that. Lacquer won't lift, no worries there.

[hobi]

Originally Posted by paint guy

The age of the paint does matter. 30 year old lacquer could be getting short and start cracking if it hasn't already. If it has, do not paint over it. If your objective is 5 year longevity with a "scuff and shoot" and there is no cracking present, there is a good chance you could acheive that. Lacquer won't lift, no worries there.

I AGREE WITH PAINT GUY I HAVE BEEN AND STILL DO SPRAYING LACQUER FOR OVER 30 YEARS, I HAVE NOT FOUND ANYTHING YOU CANT SPRAY ON TOP OF LACQUER AS FAR AS CHEMICAL REACTION OR LIFTING OR BITING IN TO EXISTING FINISH. IT IS THE STRONGEST FINISH I HAVE EVER USED AS FAR AS WHAT YOU CAN TOP COAT WITH, BUT IT IS BRITLE IT DOES CHECK AND IT DOES CRACK. I WOULD SAY FEATHER OUT THE AREAS THAT ARE CRACKED OR LIFTING OR CHECKING OR BETTER YET STRIP THEM, THEN USE WHATEVER PRIMER AND BODYWORK METHODS YOU HAVE PLANNED AND TOP COAT WITH URETHANE I WOULD GUESS YOU WOULD GET 5 YEARS OUT OF IT DEPENDING ON WHERE YOU LIVE, BUT IF YOU DONT THE GOOD NEWS IS YOU CAN START YOUR RESTORATION EARLIER.

[Ken K]

You are playing with fire trying to paint urethane over lacquer. You can get what is called a lacquer reaction. Urethane paint or primer over the top of lacquer can cause the lacquer to wrinkle up and you will have to strip all the paint off anyway. You might get lucky and it might not happen but do you want too take that chance?

[hobi]

Originally Posted by Ken K

You are playing with fire trying to paint urethane over lacquer. You can get what is called a lacquer reaction. Urethane paint or primer over the top of lacquer can cause the lacquer to wrinkle up and you will have to strip all the paint off anyway. You might get lucky and it might not happen but do you want too take that chance?

BEEN SPRAYING LACQUER A LONG LONG TIME STILL USEING IT. NEVER HAD A PROBLEM PUTTING ANYTHING OVER LACQUER, NOW PUTTING LACQUER OVER SAY ACRYLIC ENAMEL OR LACQUER OVER URETHANE ILL AGREE WITH YOU BUT YOUR WRONG ABOUT YOUR STATEMENT I KNOW IVE BEEN DOING FOR 35 YEARS

[paint guy]

Lacquer is infinitely recoatable, I have never seen any type of "lacquer reaction"
when overcoated with any type of paint. Strong solvents may partially dissolve it, but it shouldn't "lift". Alkyd enamels can and do lift when overcoated with paints that contain strong solvents because they form a film by oxidation. True lacquers dry by evaporation and will not lift, at least not any I've seen in almost 4 decades in the paint industry.

[Ken K]

I have to disagree. You can have a lacquer reaction. You can spray acrylic enamel on lacquer without problems, urethane is another mater. It's happened to me and I know painters who won't try to put urethane over lacquer. The first thing they do on those TV shows is send the car to get media blasted. GM used lacquer until sometime in the 80s. There are pictures on this site where someone got bit. Larry the guy who passed away in a motorcycle accident had a Firebird where he had problems.

[Ken K]

No one is going to use Summit paint on a nice car anyway, maybe a beater, a rust bucket or something that is left out in the elements. What happens when something goes wrong? Will they refund your money or tell you that you don't know what you are doing?

[hobi]

Originally Posted by Ken K

I have to disagree. You can have a lacquer reaction. You can spray acrylic enamel on lacquer without problems, urethane is another mater. It's happened to me and I know painters who won't try to put urethane over lacquer. The first thing they do on those TV shows is send the car to get media blasted. GM used lacquer until sometime in the 80s. There are pictures on this site where someone got bit. Larry the guy who passed away in a motorcycle accident had a Firebird where he had problems.

SPRAYED URETHANE CLEAR PPG 4000 PPG DELTRON DCH 3085 HARDENER OVER PPG DURACRYL DDL 9300 BLACK LACQUER LAST NITE ON A BLACK 1969 GTO 1/4 PANEL AND BLENDED THE DOOR NO PROBLEM BEEN DOING IT 30 PLUS YEARS NEVER ONCE A PROBLEM GOING OVER LACQUER IM DONE HERE

[stone7777]

Sorry Ken K,

Just because I am going to paint my car on a budget does not mean it is a piece of junk.

In addition, hot rodding has been built on the back of garage paint jobs and guys who do there own work.

We can not all be fat wallet snobs.

A million guys want the full frame up restoration, and guess what, they are still in the garage with boxes on top.

[hobi]

Originally Posted by stone7777

Sorry Ken K,

Just because I am going to paint my car on a budget does not mean it is a piece of junk.

In addition, hot rodding has been built on the back of garage paint jobs and guys who do there own work.

We can not all be fat wallet snobs.

A million guys want the full frame up restoration, and guess what, they are still in the garage with boxes on top.

Amen x 2 I would rather paint my car at home with budget material and probably do a better job than a shop your going to spend more time on prep that's the key and the summit material will be fine. The best material in the world does not make someone who cant or does not care have a better outcome keep going man that is what this hobi is all about

[paint guy]

stone7777: From a chemistry point of view, the 'lacquer reaction" deal makes no sense to me, but if you want to check for yourself that you won't have any recoat problems, here's how: Prepare your surface (lacquer, primer, whatever it may be) then pick a small area and apply your topcoat. Wait 10-15 minutes or so, if no wrinkling, lifting or any other type of "reaction" is present, you'll be good to shoot the whole car. Good luck with your project.

[Ken K]

Pictures please.

[hobi]

Originally Posted by Ken K

Pictures please.

I don't think you want pictures from me my material says summit on the can.

[Bob Scott]

I've used Summit SS acrylic urethane on 4 different cars in the past 5 years and have been happy with the results. I also used Summit epoxy and urethane primers on all of them with no issues. The paint also seems to be holding up well. I've attached a picture of one. These cars are every day drivers and do sit out in the weather a lot because my garage space is limited and I always have a project going on. Total expenditure on materials is less than a gallon of paint at the local Dupont jobber.

[69Customs]

I used summit's acrylic urethane on mine and for the money you can't beat it! Worked great. I went over 3-4 different previous paint jobs. Sanded them down where needed and used them to level it out. Then sealed with epoxy primer. Couple coats of 2k level. Then sealed again and top coated. That was 3 yrs ago and no problems.