If lacquer never dries/cures then why aren't people using urethane color paint?

[jchrisf]

I got to hang out with a friend of a friend who is a long time paint and body guy the other day and was shocked when he told me lacquer paints never dry.  My only knowledge of auto paint was what I learned here after starting this hobby about four years ago and everything I seemed to have learned tells me that lacquers dry the fastest.  So I asked him what he meant and he said all you have to do is wipe on some kind of thinner like lacquer thinner and the paint will come off.  He says the auto industry quit using lacquers a long time ago because of this and now only uses urethane paints.

This just got me wondering why we don't use urethane paints for our car models since we want them to look as realistic as possible and have long lasting paint.  Seems urethane paints lay down much better too.  I thought that maybe Splash, Gravity or Zero paints were urethane paints but it appears they are not.. just their 2K clears.  I guess the 2K clear will protect the lacquer underneath so it can't be damaged?  I'll have to ask him the next time I see him.  

Are urethanes less likely or more likely to damage the plastic?  He can mix any color of high grade urethane for me from 2oz and above at a great price.

[RSchnell]

Lacquer is probably THE fastest drying paint out there, it dries by oxidation & solvent evaporation. Urethanes require a catalyst which makes the paint more durable, this paint cures by chemical reaction-one of which is isocyanate, the same chemical in super glues. Urethanes are also not susceptible to humidity like lacquer and can be sprayed in any condition provided you use the correct thinner & activator. I painted Antique Cars for years- I still miss PPG's Duracryl and Dupont's Lucite. Base/Clear looks way out of place on a stock 1930s or 40s car!

There are several reasons the auto industry quit using lacquer. It's not a durable long term paint for something that sits out in the elements for years and EPA regulations.

I can't see any advantage(but always stand to be corrected!) to using 2K urethanes on a build, proper mixing would be an issue.  If you spray urethane paint on kits, you better have a darn good ventilation system & respirator, it's nasty stuff. 

 

 

[Muncie]

 

50 minutes ago, RSchnell said:

Lacquer is probably THE fastest drying paint out there, it dries by oxidation & solvent evaporation. Urethanes require a catalyst which makes the paint more durable, this paint cures by chemical reaction-one of which is isocyanate, the same chemical in super glues. Urethanes are also not susceptible to humidity like lacquer and can be sprayed in any condition provided you use the correct thinner & activator. I painted Antique Cars for years- I still miss PPG's Duracryl and Dupont's Lucite. Base/Clear looks way out of place on a stock 1930s or 40s car!

There are several reasons the auto industry quit using lacquer. It's not a durable long term paint for something that sits out in the elements for years and EPA regulations.

I can't see any advantage(but always stand to be corrected!) to using 2K urethanes on a build, proper mixing would be an issue.  If you spray urethane paint on kits, you better have a darn good ventilation system & respirator, it's nasty stuff. 

 

 

I agree

Lacquer is dry when the solvents in the thinner have evaporated.  if dry lacquer is dampened with a rag soaked in thinner, the solvents in the thinner will start to soften the paint and you will get color on the rag.  You can actually make a dry lacquer from a can into ready to spray again with enough thinner. If new lacquer is sprayed over old, the thinner in the new paint will soften the surface of the old paint makes the new paint grip better.

not a pro, but have been using acrylic lacquer on a lot of my model cars for a long time. 

 

[jchrisf]

1 hour ago, RSchnell said:

Lacquer is probably THE fastest drying paint out there, it dries by oxidation & solvent evaporation. Urethanes require a catalyst which makes the paint more durable, this paint cures by chemical reaction-one of which is isocyanate, the same chemical in super glues. Urethanes are also not susceptible to humidity like lacquer and can be sprayed in any condition provided you use the correct thinner & activator. I painted Antique Cars for years- I still miss PPG's Duracryl and Dupont's Lucite. Base/Clear looks way out of place on a stock 1930s or 40s car!

There are several reasons the auto industry quit using lacquer. It's not a durable long term paint for something that sits out in the elements for years and EPA regulations.

I can't see any advantage(but always stand to be corrected!) to using 2K urethanes on a build, proper mixing would be an issue.  If you spray urethane paint on kits, you better have a darn good ventilation system & respirator, it's nasty stuff. 

 

 

I'm wondering if maybe he meant that lacquer paint never actually cures?  This professional modeler states it in the below video at 4:10.  I don't remember him mixing anything in the color urethane paint he was using but I had a lot of info coming at me quickly so I might have missed it.  I have a 3M respirator and a Pace paint booth.  I can't smell the lacquer paints I use when I use it but I still use my respirator.  I guess with using the 2K clears I would get the protection I would want but I think I will try some urethane paint from him to see what I think about using it.

I curious what paints and clears you use on your models having had so much experience with real cars?

 

[Dave G.]

If you're painting classics era model cars 1960ish on back to 1908 you want synthetic enamel or lacquer ( and I prefer if to have to use lacquer that it's Duco Nitrocellulose not acrylic lacquer,different animal). 2k and urethane will never duplicate the look, least not factory stock. With enamel if you mix it right and shoot it right you can shoot it and forget it right off the airbrush. And it will just have that look about it.

Model A Fords had enamel on the fenders and lacquer on the bodies, fenders shot in house, bodies farmed out. Many cars were enamel that I thought were lacquer and vise versa after I got checking into it. Rods and customs of the 50 id someone could afford the paint job at all, most were lacquer. There was no such thing as 2k.

[RSchnell]

15 minutes ago, Dave G. said:

If you're painting classics era model cars 1960ish on back to 1908 you want synthetic enamel or lacquer ( and I prefer if to have to use lacquer that it's Duco Nitrocellulose not acrylic lacquer,different animal). 2k and urethane will never duplicate the look, least not factory stock. With enamel if you mix it right and shoot it right you can shoot it and forget it right off the airbrush. And it will just have that look about it.

Model A Fords had enamel on the fenders and lacquer on the bodies, fenders shot in house, bodies farmed out. Many cars were enamel that I thought were lacquer and vise versa after I got checking into it. Rods and customs of the 50 id someone could afford the paint job at all, most were lacquer. There was no such thing as 2k.

On Model A's, 90% of the enamel stuff was dipped including fenders, wheels, backing plates, etc. All bodies were sprayed in house as well. Here's a couple shots from the Model A Paint & Finish Guide.

[RSchnell]

2 hours ago, jchrisf said:

I'm wondering if maybe he meant that lacquer paint never actually cures?  This professional modeler states it in the below video at 4:10.  I don't remember him mixing anything in the color urethane paint he was using but I had a lot of info coming at me quickly so I might have missed it.  I have a 3M respirator and a Pace paint booth.  I can't smell the lacquer paints I use when I use it but I still use my respirator.  I guess with using the 2K clears I would get the protection I would want but I think I will try some urethane paint from him to see what I think about using it.

I curious what paints and clears you use on your models having had so much experience with real cars?

 

I use a variety. Everything from Tamiya spray, Dupli-Color touch up paint you get at the parts store, Humbrol enamel, Model Master Enamel & lacquers, Tamiya Acrylic and have recently been experimenting with Revell Acrylic paint. I use either Dupli-Color or Martin Senour lacquer primers on everything before topcoat.

[peteski]

Lacquers dry, but can be dissolved again using lacquer thinner.  That actually can be a good thing in many instances. But they do dry, and dry hard.

Enamels however nto only dry (when the solvent evaporates), they also cure exposed to oxygen.  It is a actually a chemical reaction which cures them hard, and they can never be redissolved again.  But both types of paints are widely used and both result in very durable finishes.

So the "never dry" statement does not really make sense (as far as paint's durability or hardness are concerned).  After all, when was the last time you cleaned your lacquer-painted vehicle using lacquer thinner? That is just silly.

Edited July 6, 2021 by peteski

[mr moto]

If lacquer never dries neither does any other paint.

Rubbing a finish with lacquer thinner is not a realistic test of whether or not a paint has dried. It will remove any other paint that I have ever used including two part epoxies. Lacquer thinner will even completely dissolve styrene.

[Foghorn Leghorn]

Acrylic  Lacquer never fully solidifies.

Fight me until your death.

[RSchnell]

1 hour ago, Foghorn Leghorn said:

Acrylic  Lacquer never fully solidifies.

Fight me until your death.

I've sure chipped off a bunch of it back in the day. If it never fully solidifies then why does it crack and shrink? I can always spot old restorations where someone put too many coats on and it has shrank and cracked over the years. While it's nitrocellulose based, add NitroStan Red Putty into the same category.

[Rick L]

Polyurethane enamel, better known as Polane is a two part mix along with a reducer for better paint flow. It’s more durable but it goes on thick with higher pressure and won’t be kind to your average airbrush. It’s nasty stuff to work with and won’t buff out like lacquer. 
Stick with hobby paints.

[StevenGuthmiller]

The real answer is......who cares!!?

we’re painting model cars. 
They’re not going to be exposed to any harsh environmental conditions.

They will sit for decades on a display shelf or be hermetically sealed in cases for all time, and if they ever are to be rebuilt, the easier the paint is to remove, the better.

Use whatever paint you’re comfortable using.

Regardless of what type it is, if you do it right and care for your models afterwards, they will very easily outlive you.

It’s just a bit humorous to me that we’re having a discussion about what the durability properties of different paints are, and yet a growing number of people have no compunction whatsoever with using a complete durability mystery like Molotow ink on their models.

In my opinion, if there was ever a potential for the complete failure of a product, Molotow is it. 😏

 

 

Steve

Edited July 7, 2021 by StevenGuthmiller

[Dave G.]

12 hours ago, RSchnell said:

On Model A's, 90% of the enamel stuff was dipped including fenders, wheels, backing plates, etc. All bodies were sprayed in house as well. Here's a couple shots from the Model A Paint & Finish Guide.

I watched a Ford documentary on this and they specifically said the bodies were done in a separate facility. Perhaps my term farmed out was out of line but they were multi color options and combinations ( 6 or 7 ) but all dipping was black apparently. Thanks for the book pages though, they only covered so much in the hour or so long video..

[Paul Payne]

Don't damage your health, don't damage the environment, and find colors you like. Remember, if you build in 1/25th scale, a single coat of paint is 25 times thicker than the same coat on a 1/1 vehicle!

[peteski]

6 hours ago, Paul Payne said:

Don't damage your health, don't damage the environment, and find colors you like. Remember, if you build in 1/25th scale, a single coat of paint is 25 times thicker than the same coat on a 1/1 vehicle!

Unless you use "model paint".

But on a serious note, I don't think that it is always the case (at least as far as I'm concerned).  I believe that paint on 1:1 cars is applied in a thicker layer than what we do on our model cars.  Well, some modelers do lay it on rather thick (especially the clear coats), so the model looks like it is dipped  in honey. At least I always  strive to minimize paint thickness.  I avoid primer as much as I can. Not using water-based hobby paints allows me to often skip the primer.  Then I don't apply 20 coats of paint to build up thickness - I apply as few coats as possible.

[StevenGuthmiller]

13 minutes ago, peteski said:

Unless you use "model paint".

But on a serious note, I don't think that it is always the case (at least as far as I'm concerned).  I believe that paint on 1:1 cars is applied in a thicker layer than what we do on our model cars.  Well, some modelers do lay it on rather thick (especially the clear coats), so the model looks like it is dipped  in honey. At least I always  strive to minimize paint thickness.  I avoid primer as much as I can. Not using water-based hobby paints allows me to often skip the primer.  Then I don't apply 20 coats of paint to build up thickness - I apply as few coats as possible.

The number of coats of paint that you can apply depends a great deal on the paint that you use. As I’ve said repeatedly, (probably ad nauseum to some of you) I routinely use as many as 6 coats of primer, 5 color coats and up to 5 clear coats. I use almost exclusively automotive primer and acrylic lacquer paints and clear, and I think that anyone viewing my builds will recognize that there is no detail hide or other issues commonly associated with heavy paint whatsoever. There are reasons why I use this number of coats of primer, color and clear that I won’t discuss here, but let’s just say that it’s because of problems with painting and finishing that I see others experience often on this forum and others. 😉

 

 

 

Steve

[peteski]

1 hour ago, StevenGuthmiller said:

There are reasons why I use this number of coats of primer, color and clear that I won’t discuss here, but let’s just say that it’s because of problems with painting and finishing that I see others experience often on this forum and others.

I don't have any problems with my paint jobs, and I never sand/rub out/or polish them, except for couple times I had to remove some small speck of dust that landed in the paint.

[StevenGuthmiller]

1 hour ago, peteski said:

I don't have any problems with my paint jobs, and I never sand/rub out/or polish them, except for couple times I had to remove some small speck of dust that landed in the paint.

I didn’t mean to insinuate that you have any problems with your paint jobs Peter, I’m only referring to the “why did the plastic craze”, “why did I rub through the paint” and “why can’t I get my paint stripped” type of questions that along with other questions, pop up quite frequently on the forums. 
I’ve had all of these kinds of problems over the years, which is how I’ve come to use the paint regimen that I use. 
I just wanted to stress that it is possible to use a lot of paint without the model looking like it’s buried in paint, and that there are some pretty strong advantages that can come from using many coats of paint.

 

 

 

Steve