Painting with automotive grade paints?

[1969racer]

I was wondering if any one has used or tried using automotive grade paints? I'm looking for some ideas and don't want to ruin the model after all the time interested in it. The cost of the paint can get pretty expensive but I have access to it from working in the industry for over 20 years. I know the paint can be real thick when applied to a model and may cover or hide very small details. Anybody having success with this?

[Ace-Garageguy]

Lots of people have been using real automotive paint on models for many years. Just reduce it properly for airbrush application (I currently use a small siphon-style automotive touch-up gun for paint, and a big ol' gravity-feed Sata clone for 2-part primers), use a decent primer to prevent crazing of some of the more sensitive kit plastics, and TEST before you commit to painting anything you care about.

I've found I can turn down the fluid and air on my big guns to apply paints and primers to models just fine. This is freshly shot with a 2K urethane primer-surfacer, using a full-sized gun.

Follow the same mixing procedures you'd use on a real car. The chemistry doesn't change just because you're painting something small. Experiment with slight over-reduction (from what you'd use on a real car) if necessary (using the appropriate reducer or thinner for the material you're using).

TEST TEST TEST, and figure out what works reliably for YOU, using the materials YOU have access to.

There are SO MANY VARIATIONS in available 1:1 paint products, nobody can tell you exactly how to make what YOU have access to work perfectly, most likely.

There are some builders who consistently get the dipped-in-syrup look from using real-car paints, and there are some builders whose paint doesn't obscure details and looks scale-correct. It's all up to you and how you handle the stuff.

I know some builders who use 2-stage urethane basecoats, and cover them with rattle-can clears (to avoid the heavy buildup some guys get with big-car clears).

Edited October 4, 2014 by Ace-Garageguy

[1969racer]

I agree with testing first! I haven't built a model since I was a kid and a lot has changed. Thanks for your input! Hopefully my builds turnout decent and I can get some good constructive criticism from some of the outstanding builders here.

[Pete J.]

Amen to the above. Been using automotive lacquers for 20 years and love them. I thin them somewhere between 6 and 8 parts thinner to one part paint to get the consistency right. At this rate a quart of DuPont lacquer will last me for another 20 years. I have not gotten into the two part paints yet but I am sure they will work just as well. If you decide to do this I have a simple but effective process for you.

Rule #1 Pick a manufacture and get all your stuff from them including thinners. They are meant to work together as a system.

Rule #2 Get a good thermometer that also displays humidity.

Rule #3 Get a small notebook and every time you paint write down the temperature, humidity and the mix rate of your paint. Then describe what happened, both good and bad. After a little while you will have a bible that will guarantee success.

Rule #4 Thin your paints accurately when you start. This BLAH_BLAH_BLAH_BLAH about "to the consistency of milk" can lead to problems. Get a container and measure up the side like a graduated cylinder and be consistent. If you do it the same way every time you will get good results with a little experience.

[High octane]

I sometimes use Dupli-Color with no problems and it can be used with Testors, Tamiya, Black Gold, and MCW primers, colors, and clears with no ill effects. At least, I've never had any.

[StevenGuthmiller]

I've been using MCW paints almost exclusively for the past several years. These are automotive colors, I believe, from Dupont. The thing I really like about the MCW paints is, They're pre-thinned for airbrush application. Just stir & shoot it on! Another thing I love about it is that the metallic in the paint is to scale for 1/25th, unlike the Testors metallics & even the Duplicolor paints. I love the stuff & will never go back! Steve

http://mcwautomotivefinishes.com

Edited October 4, 2014 by StevenGuthmiller

[Muncie]

Some automotive paints are too "hot" and will craze the plastic - not a good start for a paint job. You'll probably need something as a bariier coat between the plastic and the paint.

Many use good old Plastikote primer T-235 - it's my go to but it is fairly coarse grained which makes a thicker layer of primer. I've used automitve sealer as well - not a bad place to start - covers everything and goes under anything. Sealer comes ready to spray and requires no mixing It goes on very thin. The old can I have is Ditzler PGG DL1970.

If you ask 20 people about paint, you'll get 40 answers. As noted above find out what works best for you.

Edited October 4, 2014 by Muncie

[StevenGuthmiller]

Some automotive paints are too "hot" and will craze the plastic - not a good start for a paint job. You'll probably need something as a bariier coat between the plastic and the paint.

Many use good old Plastikote primer T-235 - it's my go to but it is fairly coarse grained which makes a thicker layer of primer. I've used automitve sealer as well - not a bad place to start - covers everything and goes under anything. Sealer comes ready to spray and requires no mixing It goes on very thin. The old can I have is Ditzler PGG DL1970.

If you ask 20 people about paint, you'll get 40 answers. As noted above find out what works best for you.

I agree with Steve! If you're going to use automotive paints, prime, prime, prime!! Nothing will ruin your attitude quicker than a destroyed kit body from crazing! I usually use 4 or 5 coats of good primer. Use what works for you but I would always rather error on the side of caution in this case. Steve

[Ace-Garageguy]

I've been using MCW ... Another thing I love about it is that the metallic in the paint is to scale for 1/25th, unlike the Testors metallics & even the Duplicolor paints. I love the stuff & will never go back!

http://mcwautomotivefinishes.com

QUESTION: I've heard before about the "scale" size of the flakes in the metallics and pearls, but for some reason, it hasn't really registered in my tiny little mind until just now. I'd really like to start using this stuff if that's the case, as the size of the flakes in everything I've been using drives me nuts.

Do you have any more information about this ??

[StevenGuthmiller]

QUESTION: I've heard before about the "scale" size of the flakes in the metallics and pearls, but for some reason, it hasn't really registered in my tiny little mind until just now. I'd really like to start using this stuff if that's the case, as the size of the flakes in everything I've been using drives me nuts.

Do you have any more information about this ??

All I can tell you Bill is what I've learned from experience from using the stuff. I assume he just uses a finer particulate metallic in his paints being as they're formulated exclusively for model cars. I've found that the metallic in the Testors paints is, for the most part, wildly out of scale for 1/25th scale, & most of the duplicolor paints that I have used are better, but still not accurate. Just take a look on my Fotki page. Almost all of my builds have been painted with MCW paints, at least all of the metallic painted ones. Some of them, like the '58 Impala, painted "Cay Coral" metallic, are almost hard to pick out the "flakes", but the metallic "sheen" is still there making the paint look much more realistic. Steve

http://public.fotki.com/stevenguthmiller/

[Ace-Garageguy]

Just take a look on my Fotki page. Almost all of my builds have been painted with MCW paints, at least all of the metallic painted ones. Some of them, like the '58 Impala, painted "Cay Coral" metallic, are almost hard to pick out the "flakes", but the metallic "sheen" is still there making the paint look much more realistic. Steve

http://public.fotki.com/stevenguthmiller/

Thanks, Steve. I looked, and that's exactly what I've been hoping to find. Thanks again.

Beautiful work too, by the way. I could spend hours looking at those pix.

[StevenGuthmiller]

Thanks, Steve. I looked, and that's exactly what I've been hoping to find. Thanks again.

Beautiful work too, by the way. I could spend hours looking at those pix.

Thanks Bill! Many times, what I'll do is basically use Duplicolor paints as my "base coat". if i can find a similar color in Duplicolor to what ever MCW paint I'm using, I'll use the Duplicolor for the first couple of coats & then the MCW for my final coat. Saves the "good stuff" for another build, plus if you're painting the body along with under hood, chassis, interior parts, etc, a 1 ounce jar can be a little light sometimes. There's nothing worse than running out of paint in the middle of a project. Steve

[DiscoRover007]

Automotive primers are cheap and awesome. The biggest issue with Duplicolor paints is that they are extremely sensitive to humidity. So the paint fogs very easily and you pretty much have to paint it in direct sunlight to get a clear shine. However if you clear coat with say testors one coat clear. The shine returns regardless. I've also noticed that Duplicolor paints show mold lines very easily. Even you sand down your mold lines and prime the body properly they can still show through. I believe the term is ghost line. I rarely get this problem with Tamiya cans. I'm guessing the Duplicolor stuff has more solvent and perhaps etches the primer.

So basically if you use duplicolor you need to work overtime on mold lines. Don't just sand them down. Even if you think it's smooth. Fill them with putty or super glue and then resand.

[StevenGuthmiller]

Automotive primers are cheap and awesome. The biggest issue with Duplicolor paints is that they are extremely sensitive to humidity. So the paint fogs very easily and you pretty much have to paint it in direct sunlight to get a clear shine. However if you clear coat with say testors one coat clear. The shine returns regardless. I've also noticed that Duplicolor paints show mold lines very easily. Even you sand down your mold lines and prime the body properly they can still show through. I believe the term is ghost line. I rarely get this problem with Tamiya cans. I'm guessing the Duplicolor stuff has more solvent and perhaps etches the primer.

So basically if you use duplicolor you need to work overtime on mold lines. Don't just sand them down. Even if you think it's smooth. Fill them with putty or super glue and then resand.

I can usually avoid those "ghost lines" by using very light coats for the first couple of coats. Once you get a "base" down, it seems you're less likely to have that problem. The heavier the coat of paint, the more likely you'll have "etching" problems. Even the duplicolor primers will etch the plastic if the initial coats are too heavy. Steve

[Ace-Garageguy]

>>>>Steve: I had the opportunity to see the MCW metallics on a couple of models today at the ACME meeting. Really good looking paint, right-appearing metallic texture, etc. The one guy I talked to extensively also says that the MCW metallics are PPG lacquer-based, and for some reason, they are much less sensitive to getting blotchy when polished (without being cleared first) than other metallics. Is this consistent with your experience?

Speaking of ghost lines, I've found that a heavy wet coat of primer over bare plastic does pull them up, but also tends to hold them down if it's allowed to dry completely, sanded flat, and re-shot with lighter coats. Sometimes multiple coats and sanding are required (I recall the Revell '50 Olds hood I de-peaked took 3 or 4 primer-sand-primer-sand-primer-sand cycles to kill the line), and to avoid filling fine details that may be adjacent to mold-line or other work, a "soft" masking technique needs to be used to protect them from primer buildup.

[StevenGuthmiller]

Bill. As far as polishing MCW metallics goes, i really can't tell you. I always use clear coats over my color coats. I just like to have the assurance that I won't burn through my color coats when I'm polishing. I usually use 3 or 4 clear coats over my paint. I really stopped having issues with mold lines when I started using my current painting system. I start with a couple of coats of Testors lacquer primer, followed by 3 coats of duplicolor primer in progressively heavier coats. Then paint & clear. I like to use the Testors primer first because it's designed for plastic & therefore less likely to give me problems with crazing. Sort of seals things up, if you will, before the "heavy" stuff. Steve

[PARTSMARTY]

I've been building for about 52 years and was a g.m. parts man for about 36 years.i've used and have tons of g.m. colors.basic primer-color and enamel clear.don't be worried that after color there may be no shine.will come back with enamel clear like model master.one thing I like about auto paint is it doesn'y attract a lot of dust.hope it heilps.

[Art Anderson]

QUESTION: I've heard before about the "scale" size of the flakes in the metallics and pearls, but for some reason, it hasn't really registered in my tiny little mind until just now. I'd really like to start using this stuff if that's the case, as the size of the flakes in everything I've been using drives me nuts.

Do you have any more information about this ??

Both Dave Dodge of MCW and Jameston Kroon go with finer metallic powders than used in the 1:1 colors when mixing their colors (Dave started doing that perhaps 20 years ago or so. With "bronzing powder"--the old technical name for all metallic powders--going back well over a century--this stuff comes in a pretty wide variety of "fine-ness". Witness the metallic silvers used on say, Mercedes-Benz cars as compared to the metallics used say, by Detroit over the years. Ever notice how "smooth" M-B's silver colors have always tended to be?

Dodge told me once when we were discussing this in my hobby shop (Dave started MCW while living in Valparaiso IN where he was a counter man at the local NAPA store there that he had to alter the mixing formula's when doing this, as merely changing the grade of metallic powder often changed the shade of whatever color of paint he was trying to mix, which does make a bit of sense, but he managed to get it pretty right.

Art

[Art Anderson]

As for "ghosting" of mold parting lines, or even where filler has been used to smooth out plastic body surfaces, this is where an airbrush and patience come in.

A little lesson I learned over the years is what lacquer thinner really does to the surface of styrene sometimes: Lacquers (even shellac) all are a "penetrating" finish at least to some extent. That is, if nothing else, a second, or further coat of lacquer laid on top of the first one will actually soften and partially dissolve the first coat (technically, you could take lacquer thinner to a real car painted with lacquer, and wash all the lacquer off the body, and respray it!). Most of the commonly available industrial lacquer thinners will also "penetrate" styrene (on pure styrene plastic they will do that with a vengeance!) and polystyrenes, causing it to swell up (when lacquer "crazes" a model car body, that is because it penetrated the surface of the plastic, causing it to swell up, but only on the surface, and having no place to go, the surface of that plastic simply has to wrinkle up!) This is rather prominent with any auto body lacquer paints, but the likes of ModelMaster and Tamiya lacquers are made using so-called "non penetrating solvents", meaning that while those solvents will penetrate previous coats of the same finish, they almost never attack the styrene/polystyrene that model car kit bodies are molded in--hence "non penetrating".

Now, a bit more technical: Even if the lacquer in question doesn't seriously craze the surface of the model body shell, it often will "release" some of the built-in stress of the plastic having been injected into the molds under tremendous pressure (upwards of 40-tons pressure) which are locked in as the plastic is chilled to harden the styrene parts so they can be demolded. This is what, in my observation over the decades I've been using lacquers on models of what causes sanded off mold parting lines to actually swell up when lacquers are sprayed on say, the body shell. Of course, as the lacquer thinners evaporate in drying, that swelling tends to shrink back, but still leaving a mark. So, what to do?

This is where an airbrush is unequaled, in my experience! I always use a lacquer primer when painting a model car body shell. I thin the stuff to at least the consistency of 2% milk (by observation in the color jar--I have no viscosimeter here), and spray the primer in fairly light coats. The first pass or two on the body shell will generally result in a light "frosting" of the surface (meaning I can see VERY fine crazing, just enough to be visible, but not so coarse as to be a problem), more so on old AMT bodies having been molded in a much harder grade of styrene, far less on more modern model kit parts made with softer grades of plastics (some brands of Japanese model kits tend to have that much harder grade of plastic which can craze much more easily). By laying on thin coats of primer, I've noticed that the "frosting" or fine crazing tends to stop, which I term in my own mind as "shock-proofing" the surface of the styrene, which allows me to get a decent, if fine "build" of the primer. After the primer has dried, I can sand the body surface to a satin finish, and almost always shoot color coats over that with impunity--no more problems.

Now, if I've done any filling, with either putty or CA glue (I tend to use both!), that alters the equation a bit. Lacquer-based putties (the "Spot & Glaze" stuff) will change that tendency of the plastic to "swell" ever so slightly, while any dissimilar fillers (CA, catalyzed putties in particular) DO NOT SWELL UP, as they are not penetrable by lacquer thinners, while the surrounding polystyrene will and then shrink back. What to do?

This is where the airbrush really shows its advantage: Airbrushes are simply miniature (or sub-miniature) spray guns, nothing more--nothing less. They can be used to spot-prime a troublesome area on a model car body, just as in a body shop, a production spray gun gets used for the very same thing. I simply spot prime such areas, let the primer dry, and wet-sand out the primer, then re-spray. Eventually that swelling up of the plastic areas is overcome, and the primer surface blends across the boundaries of filled areas of the body shell. An airbrush, well used, has the capability of doing this kind of work while not creating heavy buildups of material in the process as well.

For wet sanding primer in this process, I tend to think in miniature here: 400-grit wet or dry sandpaper is to a 1/25 scale model surface as a very coarse grinder is to the real car--so I use the coarser polishing cloths from Micro-Mesh--seldom coarser than 3600-grit. This allows me to work down the surface imperfections caused by lacquer thinner penetration around filled areas, and across mold parting lines without simply burying the surface detailing on the model car surfaces. In addition, by essentially polishing out the primer to a satin sheen gives a very smooth surface for airbrushing the color coats--often times I can get away without doing any color sanding of the color coats overall, just where there might be some surface roughness (slight orange peel, for example).

Art

[Pete J.]

Excellent description Art! Anyone who wants to use auto lacquers should read it carefully or learn the hard way!