Testors lacquer cracking FYI

[Ace-Garageguy]

I've seen several complaints that Testors lacquer clearcoats crack over time, so I thought I'd share some of my own experience.

A model I built in 2012 for the Revell contest required a hasty re-work of the decklid in order to get photos in for the deadline. I stripped the deck and primered it with Duplicolor, blocksanded and applied color and clear all in the same day, then wetsanded and polished it the following day.

6 months later, the paint on the deck had visibly "shrunk in", lost most of its gloss and showed slight orange peel. A careful sanding with 6000-12,000 grit paper, wet, and a re-polish brought it back up.

Now, almost 3 years later, there are visible cracks in the clear on the deck. There's probably not enough clear left to wetsand and polish again, but a scuff and respray with a couple more coats of clear should get it.

The rest of the model, which was given sufficient flash time between coats, and was also given plenty of shrink-time after primer, looks just like the day it was polished in '12.

The moral of the story: don't rush it.

Edited April 3, 2015 by Ace-Garageguy

[StevenGuthmiller]

Or you could just do like I do & don't use it. I built a '59 Ford a while back that has a 2-tone paint job. Coral & white. I sprayed it with several coats of Testors clear & everything looked fine.....for about 2 weeks. Then the cracking began. But, only on the coral color, not on the white. I'm pretty sure I clear coated the whole thing at the same time.

Most of the time, I had absolutely no issue with it. But it's given me enough problems where I'm just not going to deal with it anymore.

Steve

[bobthehobbyguy]

Ace thanks for the info. How long were you waiting for the flash time before clearing on the areas that were ok.

Steve were the coral and the white also testors, Also which clear.

General queation to all has anyone had the cracking when using just testors for all parts of painting?

[Ace-Garageguy]

Ace thanks for the info. How long were you waiting for the flash time before clearing on the areas that were ok.

At least a week of shrink-time of the primer before color, a couple of hours of flash between color coats before clear. Probably unnecessarily-long flash time, but this was the first model paint job I'd done in years, and I didn't want to screw it by rushing it.

Then I shot ONE coat of clear to seal the metallic, and let that shrink in for several days before 4 more coats of clear, about an hour flash between coats.

[bobthehobbyguy]

Thanks for the helpful info. I'm sure a majority of paint cracking issues is rushing the process.

[ZTony8]

I'm at work so I don't have ready access to a can but there may be a recoat window time on the label.

[Ace-Garageguy]

I'm at work so I don't have ready access to a can but there may be a recoat window time on the label.

Testors "One Coat" lacquers say " may be rercoated in about 20 minutes".

Testors basecoats (that require a clear) say 2 hours.

These are rough minimums for re-coating. There's no "wrinkle window" like there is with enamel products.

[bobthehobbyguy]

However the wild card in all of this is using different brands of paint. Not sure if flash times would be applicable in this case.

[Ace-Garageguy]

However the wild card in all of this is using different brands of paint.

Exactly, which is why on 1:1 jobs, where a LOT of time and money are at stake if a re-do becomes necessary, I stick to one manufacturer's product line...for the most part,..whenever possible.

So far I've never had a problem using one manufacturer's color / reducer / clear system (say Sikkens, for example) over another manufacturer's catalyzed primer system (like DuPont). So far...

[bobthehobbyguy]

I know tamiya and testors are a synthetic lacquer that uses alcohol as the solvent since its possible to strip it with rubbing alcohol. ?Whereas duplicolor is a true lacquer.. This may be part of the issue.

[StevenGuthmiller]

Ace thanks for the info. How long were you waiting for the flash time before clearing on the areas that were ok.

Steve were the coral and the white also testors, Also which clear.

General queation to all has anyone had the cracking when using just testors for all parts of painting?

The two colors I used were MCW & Duplicolor lacquer. I would usually give the paint about 1/2 hour, & the clear coats about 24 hours between coats. 95% of the time with no issues. But that 5% was enough to put the brakes on it for me. At least for multiple coats on bodies. I still use either the Testors "Ultra Gloss" or the "Wet Look" clear When I'm just shooting one coat on interior parts, etc. The rest of the time I use Duplicolor. Not quite as shiney on the finish, but I do like the fact that it sprays much thinner coats so there's no problem with detail hide even with 5 or 6 coats, plus it seems to dry harder & more durable than the Testors. On my next project, I'm going to shoot several coats of Duplicolor, then sand & shoot one coat of Testors to see if it will give me a little more shine without the possibility of cracking.

Steve

Edited April 4, 2015 by StevenGuthmiller

[Snake45]

A model I built in 2012 for the Revell contest required a hasty re-work of the decklid in order to get photos in for the deadline. I stripped the deck and primered it with Duplicolor, blocksanded and applied color and clear all in the same day, then wetsanded and polished it the following day.

6 months later, the paint on the deck had visibly "shrunk in", lost most of its gloss and showed slight orange peel. A careful sanding with 6000-12,000 grit paper, wet, and a re-polish brought it back up.

I had a near-identical experience with MM enamels (including Clear Top Coat) airbrushed with lacquer thinner, on an MPC 3G Camaro. I just re-polished the clear coat and it's been fine ever since.

Just as you did, I rushed the initial job, polishing it out after only 24 hours. Now I let such paint jobs dry AT LEAST 48 hours before polishing--and the longer than that, the better.

[Skip]

Typically any type of paint will be off-gassing the volatile solvents for quite a while, Enamel being the worst. The solvents are trying to go both ways as they dry, into and through the primer in the case of a "Hot" solvent like lacquer thinner especially when over reduced. I have not had this issue on paint jobs I've done since using the dehydrator to heat cure the paint, prior to that I have experienced slight panel warpage with lacquer. With enamels the main issue that I have encountered is the uncured mid-layer where that coat was not allowed to cure out and remains soft forever because its trapped between the cured topcoat and substrate. Normally this has happened when I've tried to build up the paint too quickly rather than being patient and doing things the right way, patience is not only a virtue but pays off in the long run nearly every time!

[StevenGuthmiller]

Typically any type of paint will be off-gassing the volatile solvents for quite a while, Enamel being the worst. The solvents are trying to go both ways as they dry, into and through the primer in the case of a "Hot" solvent like lacquer thinner especially when over reduced. I have not had this issue on paint jobs I've done since using the dehydrator to heat cure the paint, prior to that I have experienced slight panel warpage with lacquer. With enamels the main issue that I have encountered is the uncured mid-layer where that coat was not allowed to cure out and remains soft forever because its trapped between the cured topcoat and substrate. Normally this has happened when I've tried to build up the paint too quickly rather than being patient and doing things the right way, patience is not only a virtue but pays off in the long run nearly every time!

The only problem is, What's patience? How long do you let things cure before you re-coat. The directions on these Testors cans say any where between 20 minutes & 2 hours. Is that rushing it? Is 24 hours rushing it? Two days? A week? A month? Should I follow the manufacturers recommendations, or should I figure it out for them? This is part of the reason I've stopped using most Testors products. If they can't even give accurate instructions on how to use their products, I'm certainly not going to research it for them.

Steve

[bobthehobbyguy]

Steve the point is that testors is giving you the the recoat times when using their products. Not to belabor the point but you are using mcw and duplicolor along with the clear.

In that case you need to figure out what works. The recoat times are only relevant to using testors throughout the entire process.

[StevenGuthmiller]

Steve the point is that testors is giving you the the recoat times when using their products. Not to belabor the point but you are using mcw and duplicolor along with the clear.

In that case you need to figure out what works. The recoat times are only relevant to using testors throughout the entire process.

Ok. But does it really matter what your undercoat is as long as it's cured? Something makes me think if it's a curing time issue, that the Testors base coats would be even worse. The MCW & Duplicolor paints dry much faster than the Testors. The main thing is, I can't figure it out. I do one build with no issues, & then the next one, done identically except for the color itself, will be a problem. The inconsistency has driven me away from their products. I understand that the Testors lacquers were developed as a system, but if that limits me to using only their line, I'll pass.

Steve

[bobthehobbyguy]

I think the inconsistency is related to temperature and humidity. You'd have to monitor them everytime to see which is the most critical.

All paints are designed to be used as a system not just testors. As with most things we need to find what works for us. I'm sure there is someone out there that can get away with spraying lacquer over enamel but they will always run the risk of undesirable results.

[Ace-Garageguy]

Ok. But does it really matter what your undercoat is as long as it's cured?

Steve

It sure as jell does on real cars. I shot an acrylic urethane over a fully-cured acrylic urethane that had been shot over some cheapo (also fully-cured) mystery primer on a Pantera. When my fresh paint hit the properly-prepared recoat areas, the old topcoat wrinkled as if I'd hosed it down with hot paint stripper.

It took just about every trick I knew to get the new paint to lay down over the old stuff, and that included stripping all the wrinkled areas to bare metal and starting fresh, plus GENTLY blending all over the rest of the car.

No profit on that job.

[StevenGuthmiller]

It sure as jell does on real cars. I shot an acrylic urethane over a fully-cured acrylic urethane that had been shot over some cheapo (also fully-cured) mystery primer on a Pantera. When my fresh paint hit the properly-prepared recoat areas, the old topcoat wrinkled as if I'd hosed it down with hot paint stripper.

It took just about every trick I knew to get the new paint to lay down over the old stuff, and that included stripping all the wrinkled areas to bare metal and starting fresh, plus GENTLY blending all over the rest of the car.

No profit on that job.

That really didn't come out the way I meant it to Bill. My point was directed at the Testors clear lacquer. I've sprayed this stuff over almost everything, from enamels to acrylics with no adverse affects. A cured automotive lacquer base should have no problems handling a mild clear lacquer like Testors. I've had no problems with the Testors clear except this cracking thing & I don't know what to do different to prevent it from happening again. That is, short of going back to the old days of Testors clear enamel & letting it cure for a month between coats, & I surely won't be doing that. And I'm not going to give up my MCW paints & start using only Testors primers, color & clear. I will find ways to use it, I just no longer will use it for multiple coats on bodies any more. I just don't trust it.

Steve

[Skip]

Another point that's been touched on is Temperature and Humidity. Testor's is establishing their flash-off times in a controled environment, read that laboratory. Everything is repeatable down to time, distance, temperature in the lab and in the can, humidity, viscosity... They may even be using a hand picked can followed through the whole manufacturing process. (That way if anything fails its documented and they know where to start looking.) So any time you vary from their recommended temperature and humidity you will have to adjust flash-off time accordingly. Any time you vary from the labs surface prep (primer), you most likely will have to adjust accordingly as in experiment until you come up with a system which works.

[bobthehobbyguy]

Here is an interesting link to various paint problems.

http://www.painterssupply.net/paint_troubleshooting_guide.html

The key to getting good paint is good preparation, use compatible materials(use one manufacturers paint system ), allow for proper flash times, paint in the proper temperature and humidity This provides the best chance for success. Doing anything else is courting disaster.