Airbrush-Painting Military Miniatures and Vehicles in 1:72 Scale
A Badger 100 double-action artist airbrush with gravity-feed reservoir. Notice how small the reservoir is, yet it holds enough paint for undercoating three 1:72 scale medium tanks. The rear cover has been removed to provide easy access to the needle. The lower part of the picture shows the needle cowling (2) removed, exposing the tip of the needle (1, left of the white line) inside the nozzle (1, right of the line). Airbrushes need to be cleaned during operation occasionally, and in preparation of a change of colour. If acrylic paints are used, operational cleaning is a simple matter of wiping caked paint off the tip of the needle. Any built-up of dried paint inside the needle cowling can be scraped off with a steel awl.
Recommended Paints and Thinners
- Tamiya X20A Thinner
- Tamiya X21 Flat Base
- Pactra A48 Flat Clear
- Pactra A18 Gloss Clear
- Tamiya and Pactra Acrylics
- PRIMAcryl, AQUATEC and FERRARIO Artist Acrylics
Airbrush equipment appears expensive at first, but it’s actually a great time- and money-saving investment. If you like scale modelling, consider investing approximately $US 420.00 in proper airbrush equipment. Here is what you need:
- Compressor with large tank and regulator. The regulator is very important, it will allow you to do highly detailed work with a simple twist of the knob.
- Double-action artist airbrush with gravity-feed reservoir, medium nozzle and needle.
- Fine nozzle and needle set (optional).
- Cleaning awl.
- Acrylic paint and (non-toxic) acrylic thinners.
- Black and brown ink.
- Respirator Type FFP2, to protect the wearer from solid and water based aerosols.
There are no cheap solutions to airbrushing. Don’t waste your money on single-action airbrushes, they don’t allow the kind of detailing work you want to do in scale modelling. Forget about cans of compressed air or similar makeshift solutions, they are very expensive, and the results you get are mediocre at best. You will enjoy the freedom of using cheap compressor air to clean your airbrush, something you would never even contemplate with an expensive can of compressed air.
Do not use enamel paints for airbrush work, because these paints require enormous amounts of toxic thinners. Military modelling is an indoor hobby, and noxious vapours are known to ruin a person’s health. Enamel thinners are also highly flammable, they are not safe to airbrush indoors.
What most people don’t realize is that airbrush work is a lot easier than regular brushing. Using an airbrush, even a beginner can paint tank tracks in under 45 seconds. There is no need to mask any part of the vehicle or running gear, just turn the regulator down to 10 psi, and paint the tracks as if you were using a paintbrush. The spray is much easier to guide between roadwheels than a small paintbrush, and it provides perfect coverage with a thin film of paint. Unlike a paintbrush, the airbrush carries enough paint in the reservoir to spray the tracks of a dozen medium tanks. Unused paint can be poured back into the jar with minimal loss.
Another little known fact is that the spray from an airbrush can be regulated easily, giving the user excellent control. If you’ve only ever used spray cans, you may be loathe to consider airbrushing a true alternative to regular brush work. Take the plunge, and experience the amazing results you’ll achieve in very little time. The best way to get started is to practise the Jim Gordon technique: Weathering Small Scale AFVs.
Cleaning is quick and easy when acrylic paints are used. Paint changes are a matter of wiping the reservoir clean with a moist tissue, and spraying two or three reservoirs of water to clean the nozzle. Thick paint at the bottom of the reservoir can be released by brushing it out with a small bristle brush, and spraying more water to flush the reservoir. Dried paint residue in the sump of the reservoir is not usually a problem, it does not not obstruct the paint flow or bleed into other colours, but excessive built-up should be scraped off with a steel awl occasionally.
Airbrushing is faster and more economical than regular painting. Once you understand how the airbrush works, you will be painting five tanks in the time it took you to paint one vehicle previously. It makes sense to airbrush several 1:72 scale vehicles at the same time, because even a small gravity-feed reservoir carries enough paint to apply camouflage patterns to a dozen vehicles in one session. As a rule of thumb, the gravity-feed reservoir of a typical artist airbrush holds enough paint for undercoating three or four medium tanks.
The gravity-feed reservoir needs only a few drops of thinner and paint to become operational, it uses paint very efficiently. If platoons of five or more vehicles are being undercoated at the same time, one refill will be required which can be mixed directly in the reservoir. The paint in the reservoir can be shaded or tinted by adding a drop of black or white paint and stirring it carefully. The colour change will be effective almost immediately, because the gravity-feed reservoir feeds directly into the nozzle.
The airbrush is a cost-saver, you’ll never need to buy a can of gloss or matt varnish again, and you can spray cheap artist tube acrylic paints which will give you excellent results. Airbrush techniques suitable for vehicles may also be used to paint buildings, terrain pieces, even 1:72 scale miniatures.
Glass Bottles – The Horror
Cheap airbrushes feature detachable suction-feed reservoir cups or glass bottles, instead of the reliable and convenient gravity-feed reservoir found on real artist airbrushes. Detachable means just that, these reservoirs will detach when they are not supposed to. What’s worse, suction-feed is responsible for an unbelievable number of operating problems like air in the system, inconsistent paint flow, excessive clogging and paint spills, to name just a few. Suction-feed airbrushes with glass bottles are the worst, they only operate properly if the bottle is half-full at all times, they waste enormous amounts of paint, and they are a pain to clean. Sadly, many of these substandard airbrushes end up in the hands of beginners who are completely disappointed in the airbrush hobby within a day or two of using them. Do yourself a favor and buy an artist airbrush with permanently attached gravity-feed reservoir, anything else is a nightmare come true.
Of Nozzles, Needles, and Cowlings
There are only three parts of the gravity-feed airbrush which require attention from the user. The front of the airbrush is the needle cowling, a protective cover for the needle, which also funnels the spray. Unscrew the needle cowling to reveal the nozzle behind it. Notice that the needle completely seals the inside of the nozzle, and that it may be retracted to open the nozzle gradually. Also notice that the air is directed to flow over the top of the nozzle, not through it. When the needle is retracted, thinned paint flows out of the reservoir and is vaporized by the airstream. Gravity-feed, and the negative pressure created by the airstream flowing over the nozzle facilitate the flow of paint.
Pull the needle out of the airbrush now. Screw the needle cowling back on, and notice that the tip of the nozzle rests in a central opening in the cowling. The hole in the needle cowling is a fraction of a millimeter larger than the nozzle, a very important operating feature. Compressed air flows through a channel on the underside of the airbrush, it is then forced over the tip of the nozzle and out through the needle cowling. If the nozzle is perfectly aligned with the cowling, the air pressure will build up evenly all around the nozzle, and the spray will be directed straight ahead. If the nozzle is bent or if dirt partially clogs the opening in the needle cowling, the jet of air will be disrupted, and the airbrush will spray or spit at an acute angle.
Insert the needle again, and fill the reservoir with water. Start the compressor, and turn the regulator to 60 psi. Fully depress the trigger. Notice that a splatter of water is immediately ejected, followed by clean airstream shortly thereafter. This is a very important observation which will enable you to understand the airbrush better. Keep the trigger depressed, and start pulling it back toward you slowly. Notice that a fine mist of water is added to the airstream, and that the water spray increases the further back you pull the trigger. When the trigger is pulled all the way back, the reservoir empties in 3-4 seconds.
Popular Myth 1: Double-Action is Difficult
Double-action airbrushes are very easy to use, you’ll love them. Some people are needlessly afraid of double-action airbrushes, because they assume that air pressure and paint flow are controlled simultaneously, using only one trigger. Not so! Air pressure is controlled by the regulator, a valve and gauge mounted on the compressor, only the paint flow is controlled with the double-action trigger. Admittedly, "double-action" is a scary misnomer, we are really dealing with "phased action" here.
The key to double-action is to take it in two separate steps. First, fully depress the trigger to blow excess paint off the needle. Keep the trigger depressed, releasing a clean airstream until you are mentally prepared to take the next step. Compressor air is cheap, there is no need to rush anything. Second, keeping the trigger fully depressed, tilt the trigger toward you to add a tiny amount of paint to the airstream. Notice how the airstream changes colour and how the mist settles on the model. Less paint is better, it allows you to move the airbrush slowly and let the paint build up to the required intensity. Move the trigger forward to reduce paint, release it to stop air and paint completely. Remember to fire a jet of clean air to blow residual paint off the tip of the needle.
Popular Myth 2: Clogging Problems
Small scale vehicles and models may be painted with a medium nozzle and needle set, but a fine nozzle and needle may be even better. The finer needle set will require more frequent cleaning. If acrylic paints are used, cleaning is easy. Unscrew the needle cowling and pull the dried paint off the needle with your fingers. Use the awl to clean the central opening in the needle cowling, and remove any dried paint on the inside rim. Add acrylic paint thinner to the paint in the reservoir and stir with an old brush. If the airbrush continues to spit, pull the needle back manually, and press the trigger to eject a short jet of paint. Doing so will pull dried paint particles out of the nozzle. Add more thinner if the problem persists. In the worst case, the needle may have to be pulled for cleaning. First, pour the paint back into the jar, otherwise it will flow out of the nozzle and create a mess.
Popular Myth 3: Acrylic Paint Spit
Paint spit is an indication that the paint has not been diluted properly, it’s too dry, and the air pressure sends chunks of dried paint flying out of the airbrush. Very shortly, the built-up of dried paint will clog the nozzle and the needle cowling. Acrylic thinner reduces paint spit, and it prevents clogging. Tamiya X20A acrylic thinner is ideal for paintbrush use, it mixes well with Tamiya, Pactra and most other acrylic paints, with the exception of GUNZE acrylics. The new Humbrol Acrylic Paints mix very well with Tamiya thinner, and they are true to the popular Humbrol enamel colour numbers.
Test unknown substances before mixing them in your airbrush, otherwise they may turn into an awful slime which is difficult to clean. Paints used for undercoating should be diluted with 50 % thinner. Put the thinner into the reservoir first, then add paint. Paint used for camouflage patterns should be diluted with 60 % thinner. The more you thin the paint, the easier it sprays. Do not use water to thin acrylic paint, it reduces paint adhesion on the model. Water should be used for cleaning only.
Undercoating is not strictly necessary. If the model is cast in a dark plastic or if the overall vehicle colour is a dark green or khaki, apply the vehicle base colour directly, without undercoating. Acrylic paints will give you excellent coverage, you don’t need to undercoat them. If the vehicle is to be painted in a desert colour, undercoat in dark green to provide some pre-shading. If the desert sand base colour is sprayed on in thin layers, the dark undercoat will remain visible in the recessed lines. See Jim Gordon’s technique for details. Undercoating should be done with the airbrush held at a distance of approximately 8 cm from the model. The spray will be wider and it will cover the model more quickly. Turn the regulator to 60 psi for undercoating, and thin the paint 50/50.
The key to detailing is a clean airbrush. Nozzle, needle and needle cowling should be cleaned thoroughly in the course of an important change of paint. Turn the regulator to 10 psi. Put thinner in the reservoir first, then add paint, using a mixture of 60/40. Spray camouflage lines as if you were using a felt-tipped pen. Never point the airbrush at the model when you begin to draw a new line. The needle still holds paint from the last line, and it will splatter when the airstream is released again. Instead, aim the airbrush at your hand or a piece of paper, depress the trigger and blow the old paint out of the needle cowling until the stream of air turns clean. Point the clean airstream at the model, aim the airbrush and begin pulling back the trigger to mix paint into the airstream.
Draw the line slowly, releasing more paint if the spray is not strong enough. Make it a habit of testing the first lines on a piece of paper, and always blow out the old paint before aiming the clean airstream at your model again. The closer you hold the airbrush to the model, the thinner the line will be. Conversely, the closer you get, the less paint you should release from the airbrush. Study this relationship by spraying ink on paper.
Masking is a clever way to control the spray in airbrush work. Masking is time-consuming, and some people use it unnecessarily. In most cases, a piece of paper or cardboard can be used to shield parts of a vehicle which need to be protected from the paint spray. Do not use masking when a simple turn of the regulator screw can control the air pressure. If air pressure is reduced to 10 psi, the spray will be easy to control by hand. Masking is necessary to achieve hard lines between sprayed colours. Masking tape can be used to section off certain parts of an airplane’s wing and contain the spray. However, even if an item is masked, excessive air pressure will force paint underneath the masking tape, ruining the work.
The use of templates to spray certain camouflage patterns like the «Mickey Mouse» ears seen on British vehicles in the Normandy campaign is a form of «negative» masking. Such templates may be punched out of cardboard, using leather punches of various diameters. The templates are held against the vehicle to spray the ears on, using 10 psi air pressure. Four or five templates punched into a narrow strip of cardboard are enough to create amazing variety. Spray the outline of the pattern, then fill in the centre portion with freehand airbrush work.
Masking is very important in figure painting. The fastest way to paint cavalry is to airbrush the horses with shades of brown, and to stripe the legs with white paint applied at 10 psi air pressure. Drape a paper hood over the horse, and spray the rider in the uniform base colour. Even the shabraque can be airbrushed at 10 psi air pressure, using a small L-shaped piece of paper to mask parts of the horse immediately adjacent to the shabraque edging.
Gravity-feed airbrushes are user-friendly, and you will enjoy mixing all kinds of things in the reservoir as soon as you understand the principle of air flow and paint thinning. Dirty tank tracks are an excellent study project. Play around with the following Tamiya recipy:
- 10 drops X-20A Acrylic Thinner
- 6 drops XF-52 Flat Earth
- 3 drops X-21 Flat Base
- 1 drop black ink or paint
If you are experienced and a little daring, add small amounts of flour, talcum or baby powder to texture the mud. If the powder is stirred well, it will spray nicely. Talcum powder gives vehicles and guns that realistic textured look.
Flat and Dead Matt
Tamiya Flat Base is a matting agent which may be mixed with acrylic paints and varnishes to create a dead matt surface. Flat Base is particularly useful for that dusty finish on tank tracks and desert vehicles, it will make the viewer thirst for water. Pactra Flat Clear is probably the best matt acrylic varnish on the market today, and it may be turned dead flat with a few drops of Tamiya Flat Base. The advantage of Pactra Flat Clear and Gloss Clear is that airbrushed layers of these varnishes dry almost instantly, requiring virtually no interruption of the painting process. Again, Tamiya X20A is ideal for stretching most acrylic paints even Pactra varnishes. Thinner is much cheaper than paint, it prevents paint spit and clogging, and it speeds up the drying process, because it evaporates more quickly than water.
Airbrushing is a cost-saver for serious modellers, it reduces paint usage overall, and it uses cheap thinners to stretch paint. Airbrushed models appear much more detailed than hand-painted ones, because ultra-thin coats of paint do not obscure surface detail. If you are serious about the modelling hobby, and if you value your creative work, airbrushing is for you.