Introduction

The airbrush is considered to be an integral part of modelling. I hope to share my experience in model spray painting in this article. I have over the years spent a lot of money on airbrushes and I'd say that cleanly about 40% of the expenditure was wasted. This mostly came from the mistaken notion of getting the latest and greatest airbrush only to realise later it had a bunch of features that aren't really relevant to scale modelling. So perhaps I might be able to save you a few dollars.

Technique and considerations

The first thing to realise in modelling is, as amazing as it is, it is not fine graphic art. I can't tell you how many times I've gone through the process of anticipating painting an eagle or skull motif on a 1/16 helmet or aircraft nose only to realise that you can probably find or print a nicer decal. So really as modellers we tend to have very unreasonable expectations for airbrushes.

I've been modelling for nearly half a century and I think in order of importance the airbrush is most used for

1. Fast coverage – believe it or not it is a lot harder to brush paint a model than it is to airbrush. The main reason for this is coverage. To effectively brush paint a model it's a series of applications and thinning of paint in one direction. I have seen stunning results achieved by this. For example most large figures are brush painted and the variations from bristle brush painting can actually make for a more realistic if interesting finish. Taking the analogy of a cast shadow with umbra being the centre of the spray and penumbra being the periphery, the nature of spray that is ideal for this is a wide and uniform overspray (umbra) with minimal penumbra. The best on the market is the Iwata minispray gun (not an airbrush). The airbrush is especially necessary for gloss finishes which occurs naturally in the umbra. The penumbra effect is usually matt. You will sometimes hear the umbra being called a wet coat – it is not about simply putting 'more' in the area.
2. Feathered edge camouflage – although its very appealing to do feathered edge camouflage the reality is most camouflage on aircraft is hard edge. The feathered edge is the penumbra described above. In armour and then especially in German world war 2 armour and end of war aircraft where petrol was used to thin paint and sprayed directly by crew, feathered camouflage was common. Otherwise everything was hard edged and in modelling would require some form of masking. This can be achieved both with an airbrush or with a normal bristle brush.
3. Pre-shading - Here panel lines are marked out with a dark pigment like black to give a panel enhancement. It doesn't necessarily require an airbrush and some people prefer bristle brush pre-shading especially for modern jets that have many panels.
4. Post-fading - the centre of camo patterns especially of world war 2 aircraft and olive drab aircraft can be enhanced by this technique to make the aircraft look more striking. It can be achieved using oil filters and pastels as well but the airbrush is more commonly used in this way.
5. Clear coat - while this can be sprayed from a can it is most ideal to spray this out of an airbrush to prevent bubbling and running that often occurs out of spray cans.
6. Primer application – again this can be sprayed out of a can but for smaller projects that can cause caking (material build-up) making the airbrush a more suitable tool for the purpose.
7. Natural metal finish – similar to gloss applications it is virtually impossible to apply a natural metal finish without an airbrush (foil technique excepted). Having said that the requirements for such an application is modest and a fine airbrush is not only unnecessary it is a poor choice.
8. Special effects like gun and engine soot – here perhaps a fine airbrush may be better but in reality a black oil filter or black ground pastels give better control.

This pretty much sums up what you would want to do when in comes to laying down paint in scale modelling. Often airbrushes have three choices of tips, the Badger system features typically:

• Fine (F) - pencil line to 2" (51mm) spray pattern
• Medium (M) - 1/32" (0.8mm) to 2 1/2" (63mm) spray pattern
• Heavy (H) - 1/16" (1.5mm) to 3" (76mm) spray pattern

If I had to choose critically from the above list what spray characteristics are relevant to each category, I would state that wide sprays (2 cm diameter) are most applicable to 1, 5, 6 and 7. Medium sprays (1 cm) would be relevant to (2 and 4) and Small sprays (<1cm) 3 and 8. Fine pencil line sprays are something everyone feels is important but in the its very rarely used – perhaps for example in nightfighter lace camouflage in German aircraft like on the Me262 or He 219. Notice that what is conspicuously missing is the need to paint custom graphics like nose art or something like Tiger Meet graphics.

Nevertheless it's surprising how many times we look to an airbrush smallest line of thickness as a mark of its quality – it really is not. Also many users will claim that you need to use the fine tip for fine results. I illustrate as well as model and have experience in many sorts of media. From first-hand experience I can attest that the medium being used is more relevant. Therefore if you use a fine pigment like ink or food colouring in a fine tip you'll get the finest line but it's not relevant to modelling. If you use ink with a heavy tip it is likely to flood the subject opened up. If you use acrylic or enamel however on the fine tip its likely to clog and so these are best sprayed through the medium or heavy tip.

Before proceeding a word on Air Supply

Compressors are diaphragm or piston driven with or without reservoirs. I've had all of these. Diaphragm compressors are quieter but they breakdown quickly. Piston driven are slightly nosier. Nevertheless Silair from Italy make incredibly silent and durable compressors. I've had mine for nearly 30 years and have had to change oil twice. It's that good. Don't be tempted to get other supplies like compressed propellant , tyre tubes and gas cylinders. Just don't. Save up and buy a compressor that has a reservoir and provides at least 20 psi at the nozzle regulator (not airbrush nozzle).The reservoir evens out air flow and is absolutely essential but I wouldn't worry about getting a compressor that can drive 2 to 3 airbrushes. For most of us this just isn't relevant. A lot of reviews will talk about the merits of an airbrush in getting a fine line. What is often forgotten is that to achieve that fine line, you set the airbrush to its finest setting, then you dial down the air pressure to the point that your airbrush will spray medium but with sufficient force to continue atomisation and prevent sputter. In other words the compressor is at least as important if not more so.

So how do we choose an airbrush

A few basics that characterise an airbrush. Double action brushes in one action are able to release paint and control air. They provide the best control and thinnest lines. Single action brushes have one action for air (usually not finely tunable) and one for paint. The paint control is usually a twisting needle which can be outside the airbrush ( external mix) or inside (internal mix). While it is traditional to think of these as the coarsest of airbrushes, the legendary Paasche Model A is an external mix airbrush and has the finest line of any airbrush. There are very few internal mix single action airbrushes and the best one is the Badger 200 which I had many years ago and regrettably sold thinking I could do better with a double action brush (no, they perform the same for modelling).

So with all this as a primer which do you need? Well first look at the list above. To be honest everything in the list can be handled by a standard external mix single action airbrush. The exception to this is pre-shading and soot spray which as I've mentioned can easily be handled by oil filters and pastels. Certainly a Badger 200 could handle it. Don't forget that the head assembly for the 200 is the same for the 150 and 100 all of which are capable of fine lines. One might argue that you need the freedom to press and pull for fine lines but this is not true at all. Don't forget that many double action airbrushes have a thickness stop which effectively converts a double action to a single action airbrush to achieve fixed thin lines. The difference is in the mix. So an internal mix single action can easily do a pencil line but an external mix like a Paasche H may go down to 1.5 mm. That is still more than adequate for modeling. Its only in freehand graphic illustration that double action is important because you often want to create artistic soft effects like shadowing. That is not relevant to modelling.

In my studio, I have a number of airbrushes. The external mix airbrush Paasche H does most of the heavy work. The design is 80 years old and it is bullet proof. For detail work and touch up I use a Badger 100G which has a small gravity feed cup that makes it very easy to clean. For the nigtfighter camo and graphic illustration (on canvas) I use a 100XF sidefeed. I have seen no reason to buy another airbrush after nearly 40 years of airbrush model building. But if I were to buy one today I might get a Sotar 20/20. I am tempted by the ability to get close to the canvas and to physically wipe off tip build up but really there's nothing more to offer. The crown head of the Badger series offers this feature anyway.

Why not the Steenbeck or Iwata? In one word logistics. All my accessories are interchangeable between the Paasches and Badgers. They both are well supported in Singapore and globally. Furthermore they carry a lifetime manufacturers guarantee. In other words if they fail for any reason you can send it back to them and they will repair for free and you just pay for the worn part. It makes no sense under these circumstances to get another brand.

I have not tried the other brands but off and on many companies have tried their hand at airbrush manufacture. The brands that have made it to Singapore are Toricon , Harder & Steenbeck and Iwata. These are premium airbrushes to be sure but poorly supported and their parts are really expensive. Similarly , Tamiya and Testor (Aztek) have marketed their own. I would be hesitant about these – as we learned from Testor such airbrushes often fall out of favour and are poorly supported. They also feel cheap. To be sure feeling cheap really does affect the way an art tool performs as anyone who paints with sable brushes will tell you. By the same token the China made rip-offs of Iwata and Steenbeck may feel the same but often the fittings and thread sizes have been altered for their own purpose and not inter-changeable with the original design. The materials are inferior and you'll see this in the needle nozzle relationship. There is no aftersales service. They are cheap and you get what you pay for.

Modifications to airbrush

Over the years I've added or developed a few modifications to my airbrushes.

1. Spray delimiters – these are stops on the trigger that limit your spray width. Its useful for specific times when you want long runs of similar width lines like German lace camouflage. It came standard on the 100XF and on the Paasche V you could buy an adaptor. I got a similar design as the Pasche made for my Badger 100G and it now has similar functionality as modern airbrushes
2. Increased capacity cups – I made an extension cup for my 100G to increase its capacity to 7.5 ml. This was made from aluminium on my lathe and fits right into the original gravity mount cup.
3. Paint lids- I've made many paint lids out of aluminium. To be fair though there's not a lot of use for them.
4. Spare handle – the Paasches have fairly light bodies. This causes them to have a tendency to tip forward. These metal handles cause the airbrush to sit better in the grip.

Conclusions

There is a lot of hype about the latest airbrushes and what their capabilities are. The fact is by graphic artist standards, scale modelling is really quite crude especially when it comes to the requirements of an airbrush. No serious military modeller would purely airbrush a 1/16 military bust but perhaps anime character busts are different. In any case they really don't need a really fine airbrush to be painted.

I have learned that the most important priority in airbrushing is the best air supply you can afford followed by the airbrush that suits your needs that has good local support and after sales service. Don't do this in reverse by buying the best airbrush out there only to realise you now can only afford a cheap compressor and the airbrush parts are expensive and hard to come by. Something like a Badger 200 with a good compressor would last you for decades. Ultimately, I've always maintained that a poor craftsman will always blame his tools.

REFERENCES

1. Don's Airbrush tips: https://sites.google.com/site/donsairbrushtips/
2. Multiple Youtube videos
3. Multiple dollars spent on airbrush equipment over a 40-year period

FIGURES