TUTORIALS - 10
THE
AIRBRUSH
Which one to get
and how to use it
by Roland Meunier and Paolo Pizzi
INTRODUCTION
It is often said that what separates a beginner modeler from an intermediate/advanced one is an airbrush. We believe there is a lot of truth in that, but for a different reason than the one you may think of. For an inexperienced hobbyist, the airbrush is a very scary, quasi-mythical object, sort of a magic wand that none but the restricted circle of so-called "master modelers" is entitled to handle to perform scale magic. I'm sure many of you have gone through this phase and delayed the purchase of your first airbrush for a long time, in which you wondered whether you were going to waste money on a tool you would never be able to use.
What often happens once the beginner modeler finally finds the courage and buys the thing is also very peculiar. It doesn't take long for him/her to realize that using (not mastering...) an airbrush is not rocket science and, usually after only a few days of experimentation, the first positive results come along. But now comes phase two of the airbrush odyssey: our hero can finally spray-paint a model but the finish he/she gets is not nearly as smooth as that in the work of more experienced modelers. Because we live in an impatient society and we want everything right now, we tend to forget that the best ingredients to master every hobby, art or craft are time, patience and experience, which in turn produce skill. Instead, what often happens is that people are caught by what we call "trick fever", a sort of delusion by which the great results master modelers obtain are not directly related to decades of airbrushing models but to great secret "tricks" they must have learned sometime and to top-of-the line tools which allegedly can instantly turn an unskilled airbrusher into a master of multiple shades and hues.
The truth is that some of the greatest modelers we know have been using the same humble single-action Paasche or Badger for decades and are capable of achieving finishes that most hobbyists can only dream of, even when armed with state-of-the-art $500+ super-duper-quintuple-action tools.
Learning how to master an airbrush is not something you can pick from a book: the road to modeling glory is paved by dozens of screw-ups. Just don't be afraid of making mistakes because that's really how you learn and improve. Naturally there is also a thing called "talent" which plays a part and by which some people learn faster than others. But remember that scale modeling is a hobby and not an art and with a good dose of patience and perseverance, even the most "untalented" can eventually be gratified by their creations.
The scope of this article is not teaching you how to master an airbrush but giving you pointers in the right direction. Then several models down the line, after experimenting with air pressure, thinning ratios, different types of paint and other variables, your technique will definitely improve.
STARTING OUT
An airbrush is a precision instrument and therefore a delicate one. It requires the utmost care and a religious cleaning after every session. If by nature you are sloppy and messy, at least when handling an airbrush you should completely change your attitude.
If you have never used an airbrush, our advice is to start with the cheapest set you can buy, so that you can freely experiment without worrying too much about the fate of your tool.
The simplest airbrush one can buy costs less than 10 dollars/euros and it's something you have probably handled at some time in elementary or middle school. We're talking about needle-less single-action external-mix spray-guns which usually come attached to a siphon and are extremely easy to use (see photo on the left.) A single-action airbrush has a trigger that starts the flow of the air and the paint but it doesn't control either. The air pressure is controlled by the air source (be it a compressor, an air tank or other) and the valve that regulates the amount of paint (and consequently the size of the pattern) is a simple screw that moves the paint head up and down allowing more or less paint to be sprayed. Such a tool is not capable of producing fine lines but you should use it to learn the basics, particularly painting an object in a solid and smooth color.
Before investing in a "permanent" air source, we advise you to experiment with propellant cans. This is by far the most expensive air source and it has the disadvantage of an irregular airflow when the can is near empty (and it always comes at a crucial time, you know...Murphy's Law...), but air cans are silent and the air pressure can be regulated (even if only rather coarsely, and there is no gauge, so you'll never know the exact PSI - pounds per square inch - value you're spraying at.)
If you've never used enamels, this is not the time to try them: acrylics are a lot easier to work with (easier to clean, less toxic, easier to thin) even if they don't cover a surface as well (don't worry, nobody expects you to achieve a perfectly smooth solid color finish with just one coat...)
Armed with your simple setup (airbrush + propellant can), start experimenting with various type of acrylics until you find the one you really like (unfortunately this is very much a personal choice and therefore we can't tell you which one is the best.) Start from an average "sensible" air setting (15 PSI, if you don't have a gauge it is roughly equal to the air pressure generated by your mouth blowing air) and use the paint/thinner ratio and the thinners we recommend in our tutorial on airbrushing acrylics: CLICK HERE.
From there you can start experimenting by somewhat tweaking the variables until you find what you really are comfortable with. Remember that your initial object is to obtain a smooth solid-color surface and nothing more.
Keeping the airbrush at a distance of about 10 cm (3 inches), start spraying on a piece of paper and turn the valve ring until you get a medium spray pattern, then you're ready for the first coat on your model. Always depress and release the trigger outside the surface you are painting and move the airbrush with a steady and not too fast motion. Keep the airbrush always at the same distance from the model and moving at all times, never stop in any place or the paint will start to build up and produce a run. In order to achieve a nice smooth finish, it's much better to "build" the surface in light coats instead of trying to cover everything with one or two very "wet" coats (which are also likely to make runs.)
UPGRADING TO A BETTER TOOL
You have graduated the "basic" school and now you can paint a smooth solid color on any surface. Time to do something more complicated, but for that you will need to upgrade your setup. Don't just sell your old entry-level airbrush because you will definitely find a good use for it later. For example it can become your tool of choice to spray glossing and dulling agents, clear coats, weathering mottles etc. for which a better airbrush is absolutely not needed.
What you want now is a single-action tool with a paint-flow regulating needle. This is a very crowded category with a great number of models and several sub-types available. Let's see some of these in detail.
On the lower end of the spectrum there are external-mix (meaning that air and paint mix outside the body of the tool) tools with all-plastic bodies and no provision for multiple tips. This kind of airbrush costs in the range of 25-35 dollars/euros (for a brand name, Chinese copies can go for as low as 10-15) and it's usable for most work, except for fine lines and small details. If you are still uncertain whether to get serious or not with your airbrushing, a cheap tool can save you some money...
The Paasche H (still an external-mix type) is a modeler's "classic": sturdy and reliable, it can last for several decades as long as it is properly cleaned. Tips can be changed (half a dozen or so are available) and the smallest (No.1) is capable of tracing very fine lines. The Badger 350 is a similar model. Normally those who like a rugged tool prefer the Paasche while those who'd rather have a lighter and more pen-like airbrush use the Badger. These tools have been around from some thirty years and retail in the 50-70 dollars/euros range.
The Iwata Eclipse HP-SA (single-action) is the latest kid on the block and as such it takes full advantage of modern technology. The Eclipse SA is a computer-designed technological marvel with extremely low tolerance margins that allow for superior precision. It is an internal-mix tool: the paint is mixed with the air inside the airbrush body and the needle regulates both paint and air flow. The advantage of this system is a much higher precision, the only disadvantage is a higher cost. You don't change tip in this type but you won't need it: the very comfortable regulating ring can go from full-spray to a very fine line. High-end double-action tools (costing several hundred dollars/euros) can go smaller than that, but only professional graphic artists really need those. The retail price of the Iwata Eclipse SA is in the $/E 85 range, but you can find it discounted from several internet outlets for as low as 60-65. Worth every penny! The optional "crown cap" (an extra $/E 10, shown installed in the above photo) is a must because it allows you to do close-up work while at the same time keeping the delicate needle tip fully protected.
FREE-HAND PROFICIENCY
We mentioned before that skill is much more important than a top-of-the-line tool and in fact modelers that have taken the time to really learn how to use an airbrush can usually do a lot by spraying free-hand, when others are forced to use complex and time-consuming masking scheme to compensate for their lack of airbrush skill. Learning to airbrush fine lines and details is not at all hard, it just takes time and patience.
There are several books that teach you airbrush basic techniques but usually these are targeted to the graphic design market. You may still want to buy one of those and pick up some very useful tips. Remember though that there is a fundamental difference between spraying to a flat surface and a tri-dimensional object like a model...
We will now suggest a few practical exercises that may improve your free-hand technique. Start by trying these on a flat plastic surface. A coated piece of cardboard will do, but you must absolutely avoid any kind of paper or cellulose-based material because paint reacts in a very different way when hitting a porous surface.
#1: SPRAYING A CONSISTENT LINE
Draw a start and an end point on your practice board, separated by about 3 inches (or 10 centimeters), and try to spray a tight-pattern medium-fine line as straight and as consistent as possible. The finer the line you want to spray, the closer the tip of the airbrush should be to the surface you are painting. Crank down the air pressure as you get closer to the surface.
Common errors:
a. "Pebbly"
finish - not enough thinner in the mix.
b. The dreaded "spiders" - too much thinner
or too
much air pressure (or both.)
c. Inconsistent
airbrush motion creates widening of the line
where the side movement of the tool slows down or stops.
d. Not a straight line.
e. Inconsistent
line created by not keeping the tip of the airbrush
at the same distance from the surface.
Once you become proficient with this exercise, start changing the size of the line, going smaller and larger than before.
#2: SPRAYING ALONG A PATTERN
In the next series of exercises you should acquire the necessary skill to spray lines of different sizes along pre-designed patterns. Start with easy patterns such as crosses and zig-zag lines and then begin to include curves of increasing complexity.
#3: MOVING TO A TRI-DIMENSIONAL SURFACE
Now that you can "draw" lines on a flat surface with confidence, try in 3-D. Use a junk model (wipe the dust off first...) or a piece of fuselage, wing, whatever and repeat exercise #1 and #2 with lines of various sizes.
#4: A FIRST REAL-WORLD TEST
The soft-edged color demarcations of late WWII Luftwaffe camouflage schemes are excellent candidates for testing your free-hand skill. Naturally while free-hand airbrushing Luftwaffe camo in 1/48 or larger scale is relatively easy, it is much less so in 1/72, where masking is probably needed (unless you are a real airbrush champ...)
Try with the usual 74/75 pattern on a Bf 109G wing. Start by painting the top wing in the lighter color (RLM 75).
Draw the color demarcations on your wing using a pencil (as guides to do that you can use cutouts from a photocopy of the pattern blown out or shrunk down to match your scale) and then load your airbrush with RLM 74. Crank down the air pressure to about 10-12 PSI and move the airbrush tip as close to the wing as possible to get a fairly tight line. Now trace the lines you have drawn with the pencil, keeping the spray pattern as consistent as possible.
Fill in the color until the pattern is complete. Blending your demarcation line with the fill in is not as easy as it seems, but you will get right after repeated attempts. Don't over-spray on the RLM 75 and don't go over the demarcation too much or you will create paint buildup.
MASKING
There are several types of masks and masking materials you can use with an airbrush, depending on the type of results you want. This however is a pretty extensive issue that needs to be addressed separately. We'll cover it in a future tutorial article.
DOUBLE THE ACTION
DO YOU REALLY NEED IT?
The trigger of double-action airbrushes not only starts the flow of paint and air but also regulates it by way of a finger-controlled rocking motion.
Thus a double-action tool can instantly go from spraying a fine line to a much wider pattern. While most modelers don't really need such a tool (a good number of true masters never even bothered to buy one of these), there is no doubt that in certain instances it can be useful. For example, the above example of the 109G wing can be accomplished with a double-action tool in just one step instead of two. The modeler would have to trace the demarcation lines and then slowly open the valve and fill in the pattern. Also, double action brushes have the potential for a wider range of multi-hues and special effects. Those, however, generally require the superior airbrush skills of graphic professionals.
Double-action airbrushes are by far the most expensive. High-end tools can retail for as much as $/E 500. In our opinion, top-of-the-line double-action tools are definitely OVERKILL for modelers since I doubt anyone could fully exploit their capabilities while painting a model. If you can get a decent double-action airbrush for a reasonable amount of money, I'm sure you will find a good use for it, but only after you have acquired sufficient skill to use it.
Among all double-action airbrushes, our top pick for modelers is, again, the Iwata Eclipse, available in two versions: with siphon (shown above) or gravity feed. Although this is a fine instrument, it is priced moderately for a double action and can be purchased mail-order (or on the internet) for as low as $/E 100. In our opinion, this airbrush is superior to anything costing up to $/E 200 such as the Badger 150, Paasche models etc.
The Aztek airbrush (made by Testors) is built to an ingenious "modular" concept. It can accept side or siphon feed, a selection of tips and can perform both as a single or double-action airbrush. It also features an ergonomic hand grip and it's easy to clean. Best of all, it costs like an average single action, not even like a top-of-the-line one. But you know, as the famous adage goes: "when something is too good to be true, it probably is..." The biggest drawback of this tool is its all-plastic construction. The wheel that opens/closes the valve and switches between single and double action becomes looser and looser after only a few months of use and the plastic tips are prone to breakage (not to mention the unreliability of their plastic screw.) You can only use a plastic air hose with a non-standard attachment and, last but not least, needle tips have no protection against accidents. As you've probably figured out yourself, ruggedness and reliability are not this product's forte and therefore it's not recommended for heavy use. However we know several modelers who have obtained very nice results from this tool and they swear by that.
SPECIAL EFFECT BASICS
A. ANGLE OF INCIDENCE
Spraying with the tip of the airbrush perpendicular to the surface produces a uniform pattern which can be tightened or loosened by moving the airbrush closer or farther from the model. By varying the angle of incidence, however, you can obtain a range of interesting effects. Spraying at 45 degrees, for example, produces a tighter bottom end and a looser top end of the spray pattern.
B. TRANSPARENT COATS
Transparent coats are useful for a multitude of purposes, such as contrast reduction, paint fading and weathering.
Contrast reduction is a technique especially useful with smaller scales (a must with 1/700 scale ships, for example) whereby the contrast between the lighter and the darker color is reduced to achieve a veritable "scale effect" (lightening the colors only may not be sufficient) or to simulate the action of the elements on aircraft paint, which often results in contrast between colors being greatly reduced (think of two- or three-gray modern US navy carrier aircraft that almost appear as if they were painted in solid light blue/gray.)
Fading panels simulates the action of the sun on certain areas of an airplane. By over-spraying the darker color with a transparent mottle of the lighter one, you will achieve contrast reduction and the impression that the darker color has faded.
When aircraft are cooking in a tropical sun, the terrain reflects its hues on the airframe, especially when it's made of a solid color (like sand.) The human eye perceives this slight hue as a very transparent "overcoat" and this effect can be successfully reproduced in scale by over-spraying the model with a transparent mottle of a light sand color.
Transparent coats are achieved by boosting the thinner-to-paint ratio up to 90%, depending on how transparent you want your over-coat to be. Acrylic colors are much better suited to this kind of treatment. Some modelers use lacquer thinners in place of acrylic thinners when spraying transparent coats.
C. PANEL LINE SHADING
Closely related to the above is panel line shading. To simulate the accumulation of soot and the darker color of panel line edges, sometimes it is useful to spray fine lines along panel lines of a slightly darkened and very transparent color. This technique requires a very steady hand and a good basic airbrush skill. Some modelers use aids to keep the lines straight in the form of removable hand-held masks kept a few millimeters from the surface (such as paper or cardboard cutouts.)
D. LUFTWAFFE CAMOUFLAGE SPLOTCHES
One of the reason why WWII Luftwaffe fighters are so popular among modelers is the extraordinary beautiful camouflage schemes worn by these aircraft. Typically, the fuselage sides feature spots of a very transparent color (sometime more than one.)
The recipe for good transparent splotches is once again a high percentage of thinner in the mix (well above 50%), combined with a very low air pressure (10 PSI or even less) and spraying from a very close distance.
CLEANING THE AIRBRUSH
No matter how tedious it may appear to you, cleaning the airbrush every time it is used is an absolute must. Acrylic paint is of course a lot easier to clean, sometimes soapy water is all you need. Never use tap water though, because it may leave calcium residue in your tool, depending on how "hard" is the water in your area. Always use distilled water to be absolutely on the safe side.
Start the cleaning by spraying rubbing alcohol or an ammonia-based glass cleaner for acrylics or an industrial grade acetone-based paint cleaner for enamels, lacquers or mineral spirits. Don't forget to protect your lungs when spraying harmful substances: do it outside in a well ventilated area or wear a protective mask. Use a very high air pressure setting (50-60 PSI) and keep opening and closing the regulator valve as you spray.
In phase two disassemble your airbrush and immerse the parts in a mix of glass cleaner and soapy water (acrylics) or an industrial grade acetone-based paint cleaner (enamels, lacquers, mineral spirits.) Leave the parts in the cleaning bath for at least an hour and then scrub them as needed with an old toothbrush. Naturally the needle needs a much gentler treatment...
CONCLUSIONS
We hope these brief how-to notes have been useful to you and have contributed to making the airbrush a less scary tool. Once again, we encourage all beginner modelers to purchase an airbrush and start experimenting with that. It is not as hard as it may seem and practically anyone is capable of achieving satisfactory results, as long as there is a great deal of patience and religious cleaning is practiced every time.