Technical Clear Urethane over lacquer ? Can it be done?

Like the title says, I have a bunch of old Kandy lacquer colors that I want to use on a project. I want to clear it with catalyzed urethane. Can it be done without reacting with the lacquer?

 

You would probably have to wait about 3 months before you cleared it if it would work at all. Lacquer gasses off for a long time. Even then I would be very worried about the urethane eating into the lacquer.

 

Lots of folks have done it
We had to back when gm still used their crappy old lacquer but the clear was sprayed over OE lacquer
The paint rep will say no. I’d test it first

 

I can't say one way or another but I do know that lacquer and urethanes don't mix with furniture finishes. HRP

 

Yes you can, I would suggest using a fast thinner for the 1st coat or two of clear.

Like @Moriarity said...Back when it came out, there were all kinds of issues! I was kind of a guinea pig for a local supplier who was always trying to get me in the 20th Century! LOL. He would give me all the stuff & say...."Try this". I think the 1st one might have been called Starthane, really hard to work with.

For a definitive answer from one of the best in the business email Tammy Miller at Revolt Auto Paint. Formerly of Tamco & Orion. She always has time to answer questions & has the knowledge to give the right ones.

God Bless
Bill
https://www.jalopyjournal.com/forum...ar-transport-hauling-open-or-enclosed.614419/

 

When I was trying to figure out the paint on my truck which is lacquer I asked numerous paint experts including Jon Kosmoski from House of Kolor (an industry friend had him call me) and to a man they told me not to do it for the reasons that have been listed against it. I heeded their advice.

 

Is lacquer clear NLA? Haven't used it in years....

 

Any reason why you want to avoid using the correct product?

https://tcpglobal.com/products/rsp-cl3245-gl

 

I’ve seen urethane attack lacquer that wasn’t thoroughly cured, the results looked similar to applying paint stripper and letting it dry.
I agree use similar modern products or do it knowing your project could turn to shit over night.

 

Just wanted to use up stuff I had on the shelf for years, instead of buying a bunch of new product.

 

Just about anything can go over lacquer. Lacquer won't really go over anything except itself. In the early base/clear days the bases were lacquers reformulated to dry flat. That gave the urethane the mechanical bond @Moriarity was talking about.

Here's your homework assignment. Spray some lacquer and let it flash about 20-30 min. Have your 'thane ready to go but splash just a wee bit of good lacquer thinner in the 1st coat. I'll say probably 10% (but you don't have to be mad scientist accurate). The thinner in the clear will create that bond with the lacquer and should have ZERO effect on the clear itself. Well, it may flash quickly but not enough to go gravel. The 2nd and 3rd coats just use the clear as intended. Lacquer thinner cuts everything and as seen while cleaning your equipment it doesn't gel or cause coagulation. Just rinses all the material away while it's still liquid. This is not a some's good-more is better thing. Be conservative with the thinner.

For those of you whose blood pressure spiked reading that, relax. It won't hurt anything and has no effect on the cross-link created by the catalyst in the clear. Have I done it? Yes, and it can only be done for the 1st coat over the lacquer. The rest goes on as intended, also remaining unaffected by the 1st coat of urethane. If you're incurably concerned by the lacquer thinner the same thing could be accomplished by adding slow dry, or high temp, urethane solvent but again be conservative. No more than 10-12%. The majority of lacquer finishes will not craze or lift under anything but slow thinner or paint stripper. You'll receive an 'F' on your homework if you don't report back...


Quick edit here, the lacquer you spray over should be of the same mil thickness a decent finish will be. No less, no more. If the lacquer needs 3 or 4 coats to cover that's what you need. And finally, new guns have way better transfer efficiency than our old beloved siphon guns. Gravity feeds pile it on so volumes and pressures need to be considered. If an old gun needed 10 coats of lacquer to cover the new gun will be 6 or 7. There's more, just ask...

 

My painting skills don't travel far beyond a brush, but I really enjoy reading these discussions.

 

I did a motorcycle years ago. Turned out real shiny with a wrinkle finish in the red lacquer paint.

 

There is such a thing as waterborne urethane clear. I understand it's compatible with pretty much everything.

But when it comes to automotive finishes, it's safest to keep types and even brands the same. Ask me how I know.

There are workarounds, but sometimes it's more work and money than if you did it right in the first place. And I think a lot of us forget to consider what might happen in the future when time comes to rework the finish. And it gets sanded through and exposes the incompatible types of paint and nobody knows.

 

Here is one:,,,, what if you spray rustoleum (alkyd enamel) reduced with Acetone over lacquer ?

 

Folks been spraying catalyzed paints on lacquer primer for decades.


Just saying

 

Back in the day we used Imron clear over Clear and Kandy lacquers on motorcycle parts, we’d spray out the all the lacquer open the booth and let it sit overnight then cut it 1000 grit and then apply the Imron clear. But I think you need to have the cut with 1000 grit before the Imron to release the trapped solvents from the lacquer.
I’ll add that different urethane clearcoats have bite differently even with a urethane bace.
As a general suggestion I wouldn’t recommend using urethane over lacquer primer or color coat.

 

I did it all the time shortly after I started painting in the mid-80’s. It was back when lacquer clear would turn yellow. I would shoot the car in lacquer then color sand it with like 600.. Then, I would shoot urethane clear over it. The clear wouldn’t stick if trying to do wet on wet like base/clear today. It worked great and was better than just lacquer. But, repairing it was another story. However, not sure it would work for what you want since guessing you wouldn’t want to sand the Kandy color.

 

Wonder if a modern clear base coat would work in between

just spit ballin

 

I found some lacquer clear in my old stuff, so will shoot the base and flake in urethane then do the lacquer candy and top with lacquer clear. Just flip what I was going to do to start with. Thanks to all who replied, I appreciate it.

 

I would be concerned with the lacquer over urethane more than the other way in that it would likely make it lift? Maybe someone else knows more about that, but that’s the experience I have had.

 

The thing about different types of top and under coats is they all expand and contract at different rates, they all cure at different rates. So even after you think you got away with being a Mad Scientist mixing paint types you still end up with a mess in six months to a year.

 

It is entertaining to read these paint threads. I read everyone and take in as much information that I can hoping that one day when I paint my car I don't mess it up too bad (paint is expensive)

 

Just follow the tech sheet info
You’ll be good

 

I used to spray lacquer clear over chromabase urethane basecoat at a body shop many years ago on school buses outside because they didn’t fit in the spray booth. Dried really quick for a fast turnaround. I always thought the solvents in urethane clear would attack non catalyst paint though I’ve never tried it.

 

I just did it about a month ago. Hasn't fallen off yet. It's Black lacquer with Urethane clear. No tricks. Just sprayed it. But your results may vary.

 

Back when Euroclear came out I sprayed it over silver base lacquer because lacquer clear was a bitch to sand and buff got the truck back a bit later as it yellowed. We used to spray Euroclear over Centari enamel super deep shine.

 

Did you click on the link that I posted?

It is clear LACQUER!

 

Yes I did, like I said I was trying to use up what I had in my paint cabinet without spending any more money.