Airbrushing Part 1 - The Airbrush

Airbrushing Part 1
The Airbrush

In a highly instructional series, JAY BLAKEMORE offers insightful tutorials on choosing and using airbrushes and compressors, based on his 40 years of experience. Here he begins with the basics.

Above: Airbrushes are manufactured all over the world and come in many shapes and styles, which can make choosing one difficult if you don’t know what you’re looking for.

Airbrushes are not a new invention but, over time, they have evolved from initial crude spraying devices, although the latter’s origins are disputed. A spraying device, described as an ‘atomiser’, was patented in 1876 by American Francis Edgar Stanley, who used it in his photographic studio to colourise photographs. A similar gadget was patented in 1878 by fellow countryman and prolific inventor Ebner Piller, who also used his ‘paint distributor’ to re-touch photos. The rights to the latter were eventually sold and re-patented by brothers Charles and Liberty Walkup of Rockford, Illinois, who renamed their device the ‘air-brush’.

Above: Single-action airbrushes, such as this Iwata Revolution SAR, are easier for a beginner to become competent with, though not necessarily the best choice for the modeller.

Considered an aberration by ‘real’ artists and art critics alike – the American surrealist and photographer Man Ray being dubbed a ‘criminal’ by critics for holding an exhibition of his sprayed work in 1918 – the popularity of the airbrush really only began to grow in the mid-20th century among poster illustrators, advertisers and animators such as those at Walt Disney Studios. Those days are long gone, and the airbrush is now considered an indispensable tool among artists wishing to create photo-real images or realistic models. There remains a clique of die-hard modellers even today, however, who insist that real modellers would never stoop so low as to use an airbrush. I would respectfully disagree, suggesting that any tool which helps a person achieve his or her goals is worthy of consideration.

Types of equipment

Airbrushes are manufactured all over the world and come in many shapes and styles; there are numerous terms used to describe them, which may make choosing one seem rather complex. In fact, things are far simpler than they might appear, as all airbrushes basically have the same function; they just achieve it in slightly different ways. The similarities are that all airbrushes use a separate air source to atomise a liquid – which in these tutorials we will categorise as paint – and propel those atomised particles onto a surface. This differs from an aerosol spray-can which does the same thing but contains both the propellant and liquid in a single gas-filled container. There are different types of airbrush, however, and it will simplify things if these are broken down into distinct categories. We’ll begin by looking at the terms single-action and double-action.

Single-action

This type of airbrush is the simplest to use, as by depressing the control lever (often called the trigger, especially in America) the operator releases both the paint and pressurised air in a single motion. Simple is not necessarily better, however, as this single action does not allow scope to vary the amount of paint or air released. In their favour, though, single-action airbrushes tend to be less complex than their doubleaction counterparts and are therefore generally cheaper to buy, and this may appeal to those on a limited budget.

Double-action

Also known as dual-action, these airbrushes allow the operator to control both the airflow and paint flow by way of the lever. The first action of pressing the lever downwards releases compressed air into the airbrush, while the second action of pulling back on the lever releases a controlled amount of paint. The more firmly the lever is depressed, the greater the air flow, while the further the lever is pulled back, the greater the flow of paint. Such manipulation takes time and practice to master, and this in itself often puts people off buying a double-action airbrush. Both single-and double-action airbrushes have their uses as far as modelling is concerned, though the latter type gives the operator far more control by manipulation of the lever alone.

Above: A selection of gravity-feed airbrushes (these are all double-action units). These would be an ideal choice if using a low-powered compressor or one without an air storage tank, as paint flow is aided by gravity.

Gravity and suction

Airbrushes can be further subdivided by the way in which they deliver (or feed) paint to the point of dispersal prior to release, and these too can generally be split into two categories – gravity and suction types – with a third, intermediary version being side-mounted.

Gravity-feed

These airbrushes contain the paint or product in a cup positioned on the top of the airbrush and, as the name suggests, utilise gravity to help force the paint down into the airbrush body, where it is atomised and propelled forward by the release of compressed air. These cups come in many sizes and are generally an integral part of the airbrush body. This of course means that the amount of paint that can be used at any given time is governed by the size or capacity of the cup fitted. For this reason, airbrushes come with different cup sizes and one would naturally choose a gravityfeed airbrush equipped with an integral receptacle of suitable capacity for the tasks in hand. Some top-of-the-range airbrushes are fitted with interchangeable top-mounted cups that unscrew from the main body. The advantages of such an adaptable system are obvious.

Above: Double-action airbrushes are more difficult to master because, as the name suggests, the lever (or trigger) has two positions: pressing the lever down releases compressed air, while...

Above: …pulling back the lever and maintaining downward pressure releases the paint. This double movement is akin to rubbing your tummy with one hand while patting your head with the other!

Suction-feed

These work in the opposite way to gravity-feed devices and generally contain the paint within an under-slung jar or pot. When compressed air is released into a suction-feed airbrush a vacuum is created within the body of the airbrush, which in turn sucks the paint up from the underslung receptacle to be atomised and propelled forward. Though suction-feed airbrushes tend to need a slightly higher air pressure setting than gravity-feed versions to produce a smooth paint flow, in operation there is actually no difference between the two. An advantage of suction-feed airbrushes is they tend to have interchangeable receptacles that are simply slotted into the main body. These come in a wide range of sizes or capacities and often have additional screw-on caps, making them useful for storing pre-mixed, one-off paint colours for later use. It also means that jars containing different shades can be easily and quickly interchanged during operation without the need to completely clean the airbrush. They can be messy, however, as the slip-on jars have a tendency to slip off again when in use.

Above: Suction-feed airbrushes utilise an under-slung jar or cup for paint storage. Trouble may ensue if operating in conjunction with a low-powered air source, as an insufficient vacuum will struggle to draw the paint into the airbrush, affecting the spray pattern.

Side-mounted cups

There is a third type of airbrush that would seem to occupy a halfway house between those examined above and these are fitted with a side-mounted cup. While they are basically gravity-feed devices, they have a detachable side mounting as opposed to a permanent top mounting. The advantages and disadvantages of this type are those already mentioned.

Atomisation

Finally, we’ll take just a quick look at atomisation, as there are two more phrases you may encounter when trying to choose a suitable airbrush. They refer to the way in which paint is dispersed and then incorporated into the air stream: internal mix and external mix.

Above: Some gravity-feed airbrushes come with side-mounted, detachable cups. These are useful if different-sized cups are available and are easy to clean with the cups removed.

External

These are now generally among the most basic and cheapest types available. They are normally single-action, suction-feed airbrushes that introduce the paint into the airstream as the latter exits the nozzle of the device. The paint is therefore atomised outside the body of the airbrush and this process can be seen by the user. As such they are only slightly removed from the simple paint diffusers you may have blown through as a child at school, though some traditionalists do still swear by them. The atomisation process tends to be more random and harder to predict and therefore is harder to control than on internal-mix airbrushes.

Internal

Most modern double-action and single-action airbrushes work by atomising the paint within an internal chamber, out of sight of the user. This method is very efficient in producing a predictable paintflow and is preferred by most manufacturers of quality airbrushes and by most users.

Above: Arguably the most basic of all airbrushes is the suction-feed, external-mix type, which are commonly advertised as beginner/introductory tools. Consequently, results can be more sporadic than when using an internal-mix device, due to the simplicity of the design.

In conclusion – an important caveat

It has been stated that in operation both gravity-feed and suction-feed airbrushes perform similarly, which is true, but only if the compressor being used is up to the task. If using an underpowered compressor, one without an air storage system or one with inconsistent air pressure, then gravity-feed airbrushes might be more appropriate to your needs. It is important to note that in the author’s opinion, however, spending money on a good compressor is far more important than buying a quality airbrush and this conundrum will greater detail in the tutorials to come. In the meantime, it is hoped this first tutorial has helped you identify the different types of airbrush available by the terms most often used to describe them.