Tech Tip: Painting and Finishing Scale Models
There are a variety of how-to books out there that cover the painting and finishing of aircraft models, but one doesn't stand out in particular for me on the techniques that work for me. Everyone has a slightly different approach to painting a model and you still see hand-painted models beating out airbrushed models on the contest tables. For what it is worth, let me share my techniques for aircraft painting and finishing. I've seen what the artists who can hand-paint models turn out. I'm not one of them, so I'll stick to my trusty airbrush. I found my level of success versus frustration is directly proportional to the use of good tools.
1. Air Brushes
There are many different brands of airbrushes out there, but they essentially break down into two types: single action and double action. A single action airbrush maintains a constant air pressure at the nozzle when the trigger is pressed and the air pressure is adjusted at the compressor/regulator. Paint flow is adjusted by moving the paint nozzle in or out of the airstream. On a Paasche single action airbrush, this is done by adjusting (screwing) the paint nozzle at the tip.
Double action airbrushes can feel odd initially (like you're afraid to chew gun or breathe when using the brush) because you are using the same trigger to regulate airflow AND paint flow. The harder you press down on the trigger, the more air pressure is released through nozzle (up to whatever pressure level you've set in the regulator). The more you slide that same trigger rearward, the more paint can flow into the airstream. Full down and rear on the trigger and you're getting maximum air and paint moving through the airbrush. Once you get the hang of the double action airbrush, you can shift from covering larger areas with color to drawing a demarcation line for a camouflage color at the mere twitch of a finger.
I learned to airbrush with the Paasche H (single action), moved on to a Badger double action, and have had the pleasure of trying a wide variety of brands over the years. All of the airbrushes on my bench now are made by Iwata as they are well-made and haven't given me the maintenance problems of my previous airbrushes. Despite all of the hype out there on double action airbrushes, the single actions are quicker to clean and are excellent for laying out base colors and larger areas.
Years ago, I started out with one of those typical piston pump compressors that would pulse air through the airbrush, and while it did an okay job, the diaphragms would wear out every year or so, and the pump itself wouldn't last much longer than two diaphragms. Why? They are designed for 30-35 psi output and these compressors run continuously whether you're spraying or not. If you airbrush at 30-35 psi, you won't be able to paint small areas with precision but you can do one heck of a job spraying out that base coat!
If you put an air pressure regulator on them, the diaphragms will wear out even faster. This isn't a defect in the compressor; they just weren't intended for extended periods of back-pressure. When you're between sprays on your airbrush, there is nowhere for the excess pressure to go except around the diaphragm. Another 'feature' of these compressors is they are noisy. This is fine if you're single or wanting to be that way again...
Years ago, I invested in a Badger air compressor that had an air storage tank, automatic pump shut-off, and was only as loud as a quiet refrigerator. The advantages of a higher-end air compressor like this one are:
- Smooth, pulse-free airflow
- Constant regulated air pressure
- Relative silence while I am trying to concentrate on the model
After 12 years of service, the Badger compressor started locking up and I couldn't seem to connect with the Badger customer service folks. so like my airbrushes, I switched to an Iwata. You can see the beast here. After more than ten years of service, the Iwata air compressor is still running great!
3. Miscellaneous Essentials
If you have a decent compressor and airbrush, invest in an air regulator that has an easy-to-read pressure gauge and a water trap. The water trap will collect any condensed water vapor before it finds its way under your paint. This is annoying when you're shooting acrylics, and downright frustrating with enamels!
If you have more than one airbrush (i.e. a double action and single action airbrush), consider upgrading to a quick disconnect system like this. I can swap airbrushes as fast as mechanics swap pneumatic tools.
You'll need mixing cups to dilute your paints. I get the small cups that are disposable after one use from Hobby Lobby. While you're there, pick up a box of 1000 ice cream sticks. These are absolutely the best (and cheapest!) mixing sticks that are handy for other hobby applications as well.
These days, there even more choices when it comes to paint than airbrushes! Nevertheless, there are three essential types of paint for modeling: acrylics, enamels, and lacquers. Some people will tell you that they only use one type, but there is good reason to know how to use all three.
Acrylics are excellent for painting indoors. There are no harmful vapors to worry about (though you should still have adequate ventilation) and depending on the brand, the paints are nearly bullet-proof after drying. I use Tamiya, Vallejo, Italeri, and Gunze Sangyo acrylics whenever possible. Vallejo offers a wide range of colors though not many of them are truly 'color-matched' to any given color standard. The original Tamiya line was mostly generic colors as well, though they've been producing colors that now match various color standards. Gunze Sangyo used to offer an impressive array of color-matched acrylics in their Aqueous line, but they discontinued most of these in favor of a lacquer-based acrylic (isn't that a contradiction?) formulation. This lacquer/acrylic line is under the Mr. Color brand while the Aqueous line is now under the Mr. Hobby line. The Italeri acrylics are produced by Vallejo but come in larger bottles.
I still use enamels, specifically Testors Model Master paints, because I don't like to waste time mixing colors. I like to go to the shelf, get the bottle, and shoot the color, repeat as necessary. The Testors enamels are color-matched and easy to use. When I go to the store to pick up a new bottle of a given color to replace my three-year-old bottle of that same color, I know that the colors will match. For enamels, I use my paint booth to get the vapors outside.
I used to use lacquers for some of the bare metal finishes. With lacquers, if you spray indoors, it is vital you have a paint booth and adequate ventilation as these vapors will take you from zero to stupid in just a few minutes of exposure. There are more acrylic-based metallic finishes out there so you have choices.
One last point on painting. There is one school of thought out there that painting scale models with full-scale paint colors results in unrealistic and sometimes stark results. Sometimes this is good, but you should know about scale effects. We have a detailed write-up on this here, but the theory goes that the farther away an object is, the more faded paint colors will appear. Some like to use this, others not so much. The information is here and we also provide recommendations for scale effect colors in our online color profiles and paint guides.
The quickest way to botch a paint job is not to properly clean the model first. Styrene parts have varying levels of oils on their surfaces from the release agent used in injection molding. Resin parts will also have a mold release agent still on them when you get them home and this is just as catastrophic to a good paint job as oils. I've even found some form of preservative or coating on turned aluminum barrels that prevent good paint adhesion. Clean them all!
For best results, wash the model before you remove the first part from the parts tree. These oils and agents come off with standard dish soap and warm water. When you've assembled the model to a point where it is time to paint, wash it again. This will remove any contaminants that you had on your hands as well as dust, debris, etc.
If you don't wash the parts, the paint will not adhere to the surface and you'll see your paint start to come back off your model. Any dust left over from sanding or filing will also interfere with your finish, so use an old toothbrush to get into the panel lines and remove any left-over dust.
2. Paint Preparation
I generally set my compressor's regulator for 15-18 psi. This is a good pressure to move paint onto the model without drying it in-flight or splattering it everywhere. If you're not getting good paint flow at this pressure, you may need to thin your paint.
- Acrylics: I use my handy paint mixer to get the pigmentation mixed into the carrier, then pour what I need into a mixing cup. I use a home-made paint thinner (look here) with my Tamiya, Gunze Mr.Hobby/Aqueous, Italeri, Vallejo, Akan, and other acrylics. This does NOT work with Testors Acryl! Thin the paint to a consistency of milk and you're ready to shoot.
- Enamels: I mix 2/3 Testors Model Master Enamels with 1/3 Testors Model Master Thinner. The paint should be as thin as milk, so if you get a color that is thicker, just add a little more thinner. Ditto on the ventilation!
Modelers have different techniques and preferences regarding paint. Rather than try to quantify what others do, let me share my perspective from a modeler’s point of view:
Regardless of the subject, there are certain realities about painting models:
- Matte paints are easier to apply and dry quicker, but will cause decals to silver if applied directly over the paint
- Gloss coats are easier to use with decals, but dry slower
- Semi-gloss paints tend to be a good compromise with decal use directly over the paint and while slower to dry than mattes, they are usually faster to dry than gloss colors
I like to shoot matte colors in my modeling. When I get some time and modeling momentum going, the last thing I want to do is wait for a day or two for my first coat of paint to dry! Okay, so patience isn’t one of my ‘gifts’. If the only way to get a given color is to use a gloss or semi-gloss paint, I’ll plan accordingly, but this is a rare event. Because I use matte paints, I will leave the model to dry completely once the last color is down. I know the model is mostly cured when the smell of fresh paint is no longer detectable on the surface of the model. At this point, I’ll take an old t-shirt and buff the model down to smooth out any rough surfaces left by the matte paints. I’ll perform any touch-ups needed to the paint job, let that set for a short time, and then buff the new paint smooth with the surrounding surface.
Don't be afraid to experiment as you'll do this over and over again as you change airbrushes and techniques in the future. Find the finger position that provides a comfortable flow of paint without overspray or splatter. Find the finger position that allows you to paint a solid line with no splatter. Keep the surface that you're spraying perpendicular (90°) to the airbrush's airflow.
Do allow your paints to dry before moving on to the next color. I shoot flat colors because they dry quickly and can be handled within 10-15 minutes, depending on how thick a coat you've applied. If you're modeling high gloss automotive subjects, stick to the gloss colors. If your flat color feels dry, smell it. If it still smells, let it dry a little longer as you may ruin your work handling it too soon..
Once the colors are applied and it is time for decals, we must smooth out the surface. First, I use an old t-shirt and buff the model smooth. Flat paint leaves a course texture that will not accept decals without silvering. Gently buffing the paint smooth will significantly improve the appearance and reduce risk of silvering. When you're done, if you need to retouch anything because you buffed through the paint (it takes a little getting used to), touch up the paint and re-buff after it is dry. Now smell the model. If the paint still smells wet, set it aside for a few hours. Buffing can get to areas not completely dry.
5. Gloss Coat
Once the model is dry, apply a gloss coat over the whole model. Make sure any windows, open interiors, etc., are masked off first. You can use Tamiya or Mr. Color clear lacquers, Tamiya or Gunze clear acrylics, or do what I do - Future Floor Wax. I dilute the Future 50-50 with my home made acrylic thinner and apply it to the model. When it is dry, I buff the surface again to eliminate any irregularities in the clear surface. Reapply the Future mixture until you get a uniform gloss finish. Is it true that Future works on floors too?
With the clear coat down, I’ll take whatever time is needed to apply the markings and stencils, then let them dry completely (usually overnight). Apply your decals using a good setting solution. Microscale has a good two-part decal setting system that used to be available at most hobby shops. If you can find Micro-Set and Micro-Sol, it is still a good system. I've become a fan of Gunze Sangyo's Mr. Mark Setter and Mr. Mark Softener.
Once the decals are dry, make sure there isn't any silvering in the clear edges of the decals. Re-applying the setting solution to problem spots will usually help. For stubborn decals, I keep a bottle of Solvaset handy. Usually an application or two of that will get the most stubborn decal to conform.
I will clean up any decal adherents that flow off the decals while drying, then apply another gloss coat to seal the decals. When that coat is dry, then I’ll apply whatever matte or semi-gloss coats are required before moving on to weathering the project. Apply another coat of Future 50-50 mix to seal the decals.
One note on decals themselves. One of the reasons we buy aftermarket decals is to get either better quality or different subjects (or sometimes both) than what comes in the kit. One of my pet peeves is multi-layer decals. This is where a decal company will print a piece of art like a unit shield, multi-color national markings, or other complex graphics onto two or more layers of decal film. Once you get these home, you find out that you get the privilege of laying each layer of decal one atop the next until you complete the marking. I've heard a variety of justifications for this process but none of them impress me when I see other companies that use the same decal printers (Microscale, Cartograf, etc.) to print the same or similar markings all in one layer and all in perfect register. If you want to spend that money to create more work for yourself, go for it, but I won't waste my time.
In some recent experiences, I had a British roundel where I had to lay the red dot atop the rest of the roundel. After it had all dried, I wanted to airbrush some touch-ups and the sticky-note that I put over the roundel pulled up the red dot. Decals do not stick to decals as strongly as they do to paint. After trying another multi-layer decal out on a test-build, I applied the clear coat protection over the model and discovered in the right light a lump on the surface of the model that was the three layers of Microscale decals. Never again...
7. Panel Lines
To bring out the panel lines, you can use a brown or gray-based oil color. For the recesses around flight controls and flaps, I use a black oil color. I buy small tubes of these oils from Hobby Lobby and a can of Odorless Mineral Spirits from my hardware store (much cheaper there!).
I mix a very small dab of oil into a mixing cup of Odorless Mineral Spirits until the thinner is no longer clear. Use a thin brush to apply the oil to the panel lines. Don't worry about any messes until after it dries. If the panel lines are a little too light in spots, apply a little more. If it is too dark or there is a slight mess in a spot, use the damp Q-Tip to clean up. Dried oils respond well usually to water, but you can also use the Mineral Spirits. Don't attempt to use oils directly on flat paint as you'll see the oils run all over the coarse texture.
8. Final Coat
For glossy aircraft (airliners, VIP aircraft, etc.), I apply the same clear coat mixture to the surface to seal the oils.
For tactical aircraft, I take a combination of 1/3 Future, 1/3 Tamiya Flat Base, and 1/3 homemade thinner and apply that to the surface. Tamiya Flat Base is a milky acrylic that is not a color but will turn any Tamiya gloss color flat when mixed together. It does a great job of turning Future flat too. By adjusting the proportions of Future to Flat Base, I can get semi-gloss and variations of flatness that makes the model look like it has been re-painted in the field without even altering the color.
Another favorite flat coat option when you can find it is Gunze Sangyo Aqueous (Mr.Hobby) Clear Flat. I thin this with my home made thinner and it works great (here is an example).
Well that's essentially it. We didn't get into weathering, but we'll go over that another time. These are the steps I use to turn out my models, but as I said in the beginning, there is no one right way. Read how others go about finishing their projects and adopt bits and pieces from each modeler to come up with your own technique. Of course, don't get too comfortable with your techniques as someone is always coming up with a better paint, tool, or technique and you'll wonder how you modeled this long without that new feature. Consider this a starting point if you don't have one.
Now that you've read my painting process, and many folks follow a similar process, you’ll have to realize that if you agonize over the accuracy of a given color, you’ll literally change that color as you transform that paint from a flat to a gloss and back again. If you’ve done any pre-shading or fading/weathering, then all of that effort for pure color accuracy goes out the window. The best thing is to relax and embrace the reality that paints will fade and colors change depending on the colors underneath, the thinners used, etc. - and that is on the real aircraft/armor/whatever subject! You can go here to read up on colors and use our Modeler's Online References for color profiles and recommended paints for your next project.
Now go build something!