Airbrushing 101



Sunday, September 1, 2002


Do you own an airbrush? If so, do you use it regularly? Maybe you own one but you’re not quite satisfied with your results. Or, maybe you don’t have one, but have contemplated purchasing one. (First though, you'd like to learn how to use it).


If any of these statements describe you – (or even if they don’t) - then the following write-up should be helpful.


I’ve been using an airbrush in my model building for quite some time now, (probably 12 to 14 years). Even though cleaning it out when I’m finished is still a pain, I’ve discovered a way to minimize this unpleasant chore and as a result, maximize my airbrush’s punch.


In addition, the fine control over the paint and the potential for a splendid paint finish makes me wonder how I ever got by without airbrushing before. (Actually, I do remember: I often had to strip and repaint my models because of various problems I ran into while using canned spray paints; in addition, I often ran into problems when painting with a paintbrush by hand).



Different brands of airbrushes

Some of the old, traditional airbrushes that have been on the market (forever it seems) are Badger and Paasche. Some newcomers to the field are Testors’ Aztec and Iwata.



Main characteristics of airbrushes – Internal versus External and Single Action versus Dual Action

In general, there are two different characteristics that all airbrushes have.


The first is that they can be either an “Internal mix” or “External mix” type.  This terminology describes the mixture of the paint with compressed air that is traveling from its source – (whatever it is) – through the body of the airbrush.


As the descriptions indicate, the Internal Mix airbrush is designed to mix the air and paint internally, inside the body of the airbrush. What shoots out is a mixture of air and paint.


With an External Mix airbrush, both the paint and air meet at the tip of the airbrush's nozzle.


As is probably obvious, an Internal Mix airbrush gives you better control over paint than an External Mix one does. In addition, the Internal Mix airbrush allows for a more precise application of the paint.


The second characteristic of an airbrush is whether it is a Single Action or Dual Action type. This characteristic describes the function of the button that is pressed to start painting, (along with a knob that may be found on the airbrush).


With both a Single and Dual Action airbrush, by pushing the button down you start the air flowing through the body of the airbrush. The difference is that with a Dual Action airbrush, you pull back on this button to increase the paint flow, while with a Single Action airbrush you must turn a knob (located somewhere on the body of the airbrush) to increase or decrease the paint flow.



(Ok, that touches base on the airbrush itself. Now, how about the air sources?)


Air Sources

(Disposable) Air Propellant Cans

I previously mentioned that you need an air source to supply compressed air to your airbrush. There are a number of options that exist here. One is a can of compressed air. Badger, Paasche and Testors all produce them.



An advantage of using a can of compressed air is its low cost. These cans generally run anywhere from $10 to $12.  A second advantage is that they are quiet to use.



Unfortunately, there are numerous disadvantages. The first is the limited use. You’re not going to get a whole lot of air out of these cans, and you very well may end up using two or three cans to complete the paint job on your model. With this, the relatively cheap price of individual cans can quickly add up.


Next, you have very little control over your air pressure. The air initially comes out full force, until it starts dissipating, at which point your air pressure (naturally) will decrease.


Another thing that I’ve noticed when using a can of propellant air is that the can (along with probably the air) tends to get very cold. (Ice had formed on the outside of the can around the attachment that I had once used).



Air Compressors

For the modeler who is going to use an airbrush for the long haul, this is a better source of air than the propellant can.


There are many different manufacturers of Air Compressors, with different models having different features.



Advantages are you now have a practically unlimited source of air that comes out at a constant rate. (Even though the motors on most compressors are only guaranteed for a limited number of hours, I've personally gotten 12 to 14 years of use out of my Badger 180-1 Compressor. And, despite the occasional crash down onto the floor, it is still going strong).


A second advantage is that with the addition of an air regulator, the air pressure can be controlled.


A third advantage is the quietness of some of the compressors. (You may have to shop around to locate one that runs quietly, though).



A disadvantage is the price of this modeling tool. Traditional “Hobby” compressors generally run $150.00, up. I was able to locate several VERY reasonably priced compressors at the Home Depot Store. There were two models manufactured by Campbell Hausfeld, which ran $79 and $99.


A second disadvantage has previously been listed as an advantage. Some compressors make a good deal of noise. (Again, you should shop around for one that runs quietly).


A third is a somewhat minor attribute. However, it still exists.  Since a compressor runs off of electricity, this ultimately will add a bit to the overall expense of painting a model.



Air Tanks

These are just large, metal tanks that are filled with compressed air.



The prices of these can vary greatly. However, some very reasonable options may be available here. For example, it may be possible to obtain an old scuba tank to use. With the fitting of an air regulator, you’ll be ready to go.


In general, you can probably obtain an air tank for less than the price of an air compressor.


Another advantage is that air tanks are very, very quiet.


A third advantage is that you can paint a good number of models before having to refill the tank.


Finally, since it doesn't use electricity, you won't be adding to your electric bill with its use.



A disadvantage of using an air tank is the routine expense associated with refilling it. Ultimately, it will run out of air. This fee probably will not be all that high, though, once you find a location that can fill it up.


A potential disadvantage is that air tanks tend to be large and bulky. Also, they can be pretty heavy, which may become a factor with the regular transport that the tank will go through, with it's refilling.



Air Compressor & Tank Combination

Combined air compressors and air tanks also exist. They can be obtained from a variety of sources, like Sears, home improvement stores (like Home Depot again) and some hardware stores.



This can be viewed as the “best of both worlds.” Because the compressor runs, filling up the tank (which is the primary source of the air), these tend to be quieter than air compressors.


In addition, since your compressor is attached to your air tank, the need (along with the associated expense) of having to periodically refill the tank has been eliminated.


Another advantage is that since your compressor is not continuously running while you're painting, you are going to be using less electricity than with a regular air compressor.



Well, there's not much here. You can purchase an air compressor/air tank combination for around the same price as some air compressors. Actually, the price is often cheaper, (probably since they aren't being sold as "modeling hobby" products alone).


The size may be a bit of a disadvantage, since most of these are larger that the straight air compressor.

However, they also tend to take up less space than an air tank.



(That takes care of the airbrush's air source. How about the paints and thinners?)


Paints & Thinners – (acrylics, enamels and lacquers)

Ok, now that I’ve dispensed with the air sources, I can move onto paints and thinners. You can use all sorts of “regular” paints in your airbrush. These include acrylic paints, enamel paints and lacquer paints. I’ve even heard or folks who want an exact color match - (that may only be available in a can of spray paint) - spray the canned paint into a small container, thin it down with some thinner and airbrush it on.


In addition, there are other guys whom I know of who have used women’s nail polish, mixing it in with lacquer thinner and airbrushing it on. – (Women’s nail polish is a lacquer paint).


Nowwww, folks may look at you kind of strange at the checkout counter as you pay for your “unique” model paints. However, the numerous, different types of vibrant colors available from this source make a bit of potential uncomfortableness worth it.


Generally, regardless of the type of paint that you use, you’re going to have to thin it down in order to get it to flow smoothly through your airbrush. Otherwise, it’ll be too thick and won’t come out smoothly, (but will splatter and very well may not come out at all).


An exception to this rule is Model Master Metalizer Paints, (which are composed of small, metallic flakes floating around in a diluted lacquer medium). In addition, the newly released Alclad II paints, (that are also diluted, lacquer based metallic paints) don’t need to be thinned down before using.


General rule for thinning paints

The rule of thumb here is to use the thinner that’s the same type as the paint. However, as is the case with just about everything in life, there are exceptions here as well.


You can mix “hot” thinners in with enamel paints. These include Lacquer and Xylol (or Xylene) thinners. Be veeerrrrrry careful with them, though. Use them in a well-ventilated area. Also, you should use them while wearing a respirator.


Both thinners are very powerful and can do your body BAD if breathed in. The Xylol (Xylene) is actually listed as a nerve agent.


A reason these potent thinners are sometimes used by modelers is because of their rapid curing time. The paint will cure very quickly (in a matter of seconds or minutes), allowing multiple colors of paint to be applied onto your model in one building session.


Another exception to the “thin the paint with the same type of thinner” rule is with acrylic paints.


With Polly-Scale acrylic paints, you can cut them with regular ole' windshield wiper fluid. (When you get the chance, compare a gallon of the blue-tinted windshield wiper fluid with Polly Scale's "standard" thinner).


With the Windshield Wiper Fluid, you get a WHOLE lot more liquid at a fraction of the price of the more expensive, name brand thinner.


I've also heard of folks successfully thinning other types of acrylic paints with a combination water, alcohol and a drop or two of liquid dish detergent. This dish detergent helps break up the surface tension of the water, that otherwise might cause your acrylic paint to bead up on the surface of your model.



(Onto airbrush accessories)


Miscellaneous airbrush accessories

There are several additional items you might need to attach to your airbrush.


An Air Regulator

I briefly mentioned an air regulator earlier. This is a device that allows you to decrease the air pressure that's coming from your compressor or tank. Since an unregulated air source is generally too powerful, this tool is very helpful in giving you better control over your airflow.


A Moisture Trap

A moister trap does as it sounds. If you are airbrushing on a humid day, it's possible for some of the humidity to accumulate within your airline in the form of water droplets. When they make their way towards and into your airbrush, the results are quite unpleasant. Your paint will just stop flowing or may oscillate, until the water finally comes out, mixing in with your paint and splattering onto your model.


The moisture trap can be either a plastic or metal cylinder. It's inserted into your air line, (that's coming from your compressor), with your air line cut in two and the moisture trap attached in between.


Both the moisture trap and the air regulator can be purchased from Sears and Home Improvement Centers. The can also be purchased from specialty - (here's that word again) - "hobby shops." Also, I'm pretty sure Squadron Mail Order carries them as well.



(Ok, I've discussed airbrushes, air sources, paints & thinners and miscellaneous items that you can attach to your airbrush - It's time to get to the actual airbrushing!)


Time to airbrush -Three variables to master

There are really only three factors that you must master in order to get good results with your airbrush. They are:


Your paint to thinner ratio

Your air pressure and

The distance the nozzle or tip of your airbrush is from your model


For the first factor, I generally airbrush with Model Master (Testors) enamel paints, (although I’ve used Tamiya acrylics, M.M. lacquers and Floquil lacquers as well). I mix my M.M. paints at somewhere between 1/3 to 1/4 of thinner to 2/3 to 3/4 of paint. Also, I tend to stick with the Model Master name brand thinner.


For the second and third factors, they are both related. In general, the lower your air pressure, the closer you can get the tip of your airbrush to your model, without having the paint “pushed” all over the surface.


If you turn your air pressure down and pull your airbrush away from your model’s surface, you will probably end up with a grainy paint finish. Or, the paint may not even reach your model at all. (With the grainy paint finish, what's happening is your paint is drying just as it reaches your model's surface).


Conversely, if you increase your air pressure and pull your airbrush away from your model, you're going to get more of a full-paint coverage, as opposed to airbrushing small areas on your model, (like with the camouflage paint scheme on an aircraft or armor piece).


If you are too close with your increased air pressure, you will loose control over the paint flow and the airbrush will act just like a can of spray paint that's too close to the item that's being painted: the paint will be blown forcefully and pool on your model.


I usually turn my air pressure WAAAY down, (to between 10 to 5 pounds per square inch). For the distance, I'm usually most comfortable with my airbrush being 3 - 6 inches away.


In order to get a very fine application of paint with your airbrushed, you may have to move your airbrush much closer to your model - maybe 1/2 inch to an inch and a half. Also, your pressure will need to be turned WAAAAY down, (to prevent your paint from splattering over your model's surface).


Mixing your paint and thinner

You can both mix your paint in and apply it from a small paint jar or a metal cup. Both usually come with your airbrush.


With a bottle, you can mix up a batch of thinned down paint, apply it and put the top back onto the bottle, using it later in future airbrushing sessions.


With a cup, you pretty much mix what you need, using it in your airbrushing session. If you have any extra left, you can pour it back into the original bottle your paint came from. Even though it's diluted, it can still be be poured back in.


With the use of a cup, I tend to squirt my thinner in first (with an eye dropper), followed by pouring in the desired amount of paint. Then, using a trick I learned from a modeling bud (named Joe Smith), I press a Q-tip onto the tip of the airbrush and push down (and pull back) on the airbrush button. The air and paint go all the way through the body of the airbrush, and then are forced back into the cup, with air bubbling in the paint & thinner mixture, mixing everything together.



Some potential airbrushing problems

There are a number of problems that one can run into while airbrushing. Some are listed below:


1. A dirty airbrush, (or one that has not been cleaned adequately), can cut down on paint flow, or prevent it from coming out altogether.

2. A bent airbrush needle can cause an uneven flow of paint to occur.

3. A damage airbrush tip can cause an uneven paint flow, or cause your paint to splatter.

4. Moisture in your airline can cause an uneven flow of paint & air, may stop your paint from flowing entirely or may cause water drops to splatter onto your painted regions.

5. Paint that's either too thick or thin; if too thick, it either will not come out at all, may come out unevenly or may splatter onto your model's surface; if too thin, you paint will end up running once applied to your model's surface.

6. You are either too close or too far away from your model. (Details on these problems have been mentioned above).



Maximizing your airbrush's punch and cleaning it out

A way to maximize your airbrush's punch is by painting numerous models and/or colors on in one airbrushing session.


With the use of an airbrush cup, you can just shoot some thinner through your airbrush when you're finished with one color before beginning the next. Airbrush the thinner through until it comes out clear. You don’t have to be so thorough in cleaning your airbrush out in between colors.


When you're finished painting for the session, once again shoot the thinner through your airbrush until it is clear. Then, dismantle the brush and clean out it's "innards." Q-tips, pipe cleaners and (generic) paint thinner can be used for the cleaning.



Practice, practice, and PRACTICE some more!

As with any type of newly learned technique or procedure, you’re going to have to practice to get comfortable with using your airbrush. And then, you’re going to have to practice some more to get good with it.



Practice exercises - painting small dots and thin lines

An exercise you can do to help get better control over your airbrush is to paint small dots and regions. See how small you can go. Also, see how sharp and defined you can make the regions.


In addition, you can try to paint small, thin lines. See if you can make them look as you're picturing them.


You'll be concentrating here on varying around your air pressure, (turning it waaayyy down), along with changing the distance from the item that you're painting. Your distance should be decreased down to a half an inch to maybe one or two inches, and your thinner to paint ratio may need to be thinned down more than usual.



Some advanced painting techniques

Painting different types of demarcation lines

There are many models that call for a multiple colored, camouflage paint scheme. There are a number of different ways these multiple colors can be airbrushed on.


If you paint your patterns free hand, the resulting demarcation (or separation) lines will have "soft" edges to them, with a gradual transitioning of a color. With this technique, you should angle your airbrush in towards the center of the region, to help get a defined separation line. Go around and completely paint your outer line, before going back and filling in the center.


On the other hand, if you apply tape or some other type of masking medium to your model, create your patterns and airbrush over this, you will be able to achieve sharp, crisp separation lines.


The third option here is to apply some tape (or paper with a sticky backing) to your model, and raise it up a bit off the model's surface. Airbrush directly down over these taped areas. The lines that result will be somewhere between the two previous types.


“Accentuating” one side of a line

This is a weathering technique that can be used to emphasize, or bring to life panel lines. By placing an index card, sheet of Post-It paper or applying some tape to one side of a panel line, tilting it back away from the line and airbrushing a (darker) color onto the line or onto the masking material you can create a shadowing, weathered effect on the uncovered side of the panel line. The panel line will be highlighted, with the darker color that's just been applied gradually decreasing in intensity the farther it gets away from the line.


“Accentuating” the panel lines themselves

Panel lines themselves can be brought to life by airbrushing a darker color directly onto them. It's best to select a slightly darker hue of your base coat(s) for this. If you go with Black, for example, the contrast will be too stark, making the effect look unrealistic.


With your airbrush's air pressure turned waaay down, your paint thinned down a tad bit more than usual and the tip of your airbrush up close to your model, very carefully paint a thin line over the panel lines.


(Note: After you apply your darker panel color, it may be necessary to go back and repaint your original base coat(s) on again, blending everything back together into a more uniform look).


"Reverse-shading (or shadowing)"

A painting technique that's recently "become the rage" is something called reverse shading (or shadowing). This is actually very closely related to the technique just described.


The difference here is that this darker color is applied onto your panel lines BEFORE you apply your basecoat. After it dries, your lighter colored basecoat is applied as usual.


If done correctly, the darker panel lines that were originally painted will end up "peeking through" your basecoat(s), giving the panel lines a darker, weathered look.


Weathering panel and color regions on your model

This weathering technique is related a bit to the shadowing of panel lines. You again want to shoot for very subtle color changes.


What's involved here is the painting of a lighter color of your basecoat onto the center regions of a panel section or colored area. Conversely here, the outer areas of these sections can be painted a darker color, to give a similar contrast in color.


By carefully applying a lighter hue of your basecoat to your center regions or a darker hue to the outer regions, and then going back over and "dusting" the original base color back onto the entire region a very nice, subtle highlighting/shading/weathering effect can be obtained.


Shadowing and highlighting your entire model using a "misting" technique

Another airbrush technique that you can use is the misting on of a slightly darker or lighter shade of your basecoat over your entire model. Using a lighter color over a darker basecoat (correctly) can add a nice, lighter bleached look to your model. Conversely, misting on a darker color will give your model a more dark & dirty look.


What's involved here is moving your airbrush waaay back from your model, (somewhere between 12 and 24 inches), turning your air pressure up a bit, and lightly dusting your color over your entire model.

Applying “in-scale” paint touch-ups

An airbrushing technique (or trick) that I learned many moons ago deals with “in-scale” paint touch-ups.

With actual military aircraft and armor units, their painted surfaces constantly get damaged with the heavy, extensive use that they go through.

Panel covers are constantly opened and closed, surfaces are scratched and dented and paint gets chipped. In addition, it may be necessary to replace existing outer parts with new ones, (that may have a slightly different color).

In the natural environments of these weapons of war, the exact, originally applied color is often not available. However, it’s still important to cover any exposed bare metal areas, (for the obvious reason that the metal will otherwise corrode and rust). In this situation, any old green or brown or gray or black (or any other color) will do.

If you’ve ever attended an airshow, you’ve probably noticed that up close and personal, military fighter aircraft often have different shades of green or gray or blue applied.

The technique of applying a slightly different hue or shade of an original color can also be applied to your small-scaled representatives of the real thing.

This technique works best, though, if applied to a large-scaled aircraft or spacecraft, like a 1:48 scale aircraft or a 1:35 scale armor piece. This is because realistically, you wouldn’t be able to make out these slight, subtle color changes with, say a Star Trek spacecraft.

Basically, what you want to do is get a similar hue or shade of your basecoat color and carefully apply small, tiny patches or strips to it.

Let’s say you’ve finished your Colonial Viper in a Light Ghost Gray basecoat. You could go back and apply small, thin regions of Gunship Gray to some regions, and a Camouflage Gray to others.

Subtlety, variation and restraint are the keys here. You are shooting for barely noticeable, arbitrary color touch-up variations; you want the color additions to blend in with the original colors and you want these areas to be very small in nature. However, you still want them to be (barely) detectable to the human eye.

Try to picture, if you will a small, in-scale person touching up the paint on some areas on a X-Wing fighter that may have been damaged in a recent battle. How large do you think these touch-up areas should be?

(Once again), it will take a good amount of practice to get some really good results from this technique.



Airbrush Web Sites:

Found below are some of the different airbrush Web Sites that exist. I’ve visited all of them, and in addition to the (obvious) parading around of their products, there is also a surprisingly amount of helpful information contained within them.




(Testors - Aztec)





In order to get a really nice looking, smooth paint finish on your model, the airbrush route is often the only way to go. Adding to the mix - (please forgive the pun here) - the fact that quite often, a customized, unique color combination can only be applied with an airbrush, (and applied in some pretty spectacular ways) makes using an airbrush indispensable.


Often though, learning and mastering a new, mysterious modeling tool can be daunting and intimidating.


By taking it slow and practicing with your airbrush, any initial hesitation and reluctance at using it should quickly be replaced with a joy at newly discovered possibilities that an airbrush can open up.


(Back to the Tips n Techniques Page)



Copyright © 2012 by Anthony I. Wootson. No material may be reproduced without permission. Unauthorized duplication is prohibited.