Posted on by Metro Hobbies

For many hobbyists, purchasing an airbrush and compressor is a big step in their hobby journey. Many hobbyists are intimidated by the investment in the necessary components to begin airbrushing (as well as the associated paints, thinners and accessories), so much that they become fearful that they may not get the best out of the investment.

In Metro Hobbies' collective experience, airbrushing as a skill takes your hobby enjoyment to the next level. Much like learning how to drive, once you learn how, you would begin to wonder why you didn't take that step sooner!


Above: Two versions of a single-action airbrush.

The Basics

Atomising paint tools using compressed air was first invented in the 1870s in the USA. They were first designed to be used for industrial manufacturing (spray guns) and simplified the work of painting many large objects quickly (as well as saving on paint, and drying paint quicker).

Eventually airbrushes came to be used by artists. The basics haven't changed, but in the last decade or so there had been quite a revolution with the affordability of airbrushes and compressors, water-based paints, as well as the airbrush designs themselves that one can happily jump into the painting straightaway with little or no experience, and come out of it satisfied in taking the step.

Why use an airbrush at all?

There is no hard and fast rule on when you should or shouldn't use an airbrush. The base principle works the same as any aerosol can: paint is 'misted' and spattered over a surface as a fine coat by compressed air. The airbrushes' different designs provide control the flow of paint and the the air pressure that gives the user control over the width of the spray, the feathering of the edge, and the amount of the paint.

Above: An example of feathered camouflage effects with an airbrush.

So ideally if you want to paint a large area evenly or simulate a feathered camouflage scheme, then using an airbrush is the answer. Take note though that many experienced modellers prefer to use a hand brush still for large areas, and others use an airbrush even for small scale figures. There is not right or wrong answer, but suffice it to say it will always go down to the modeller's preference.

Single-Action or Double-Action

A single-action airbrush is the more basic type of airbrush one can use. Available in either pen or gun form, the principle of the single-action isn't too far from a spray can. There is only one trigger (ergo single) which controls the release of air. This draws the paint up (or down) from the paint container and initiates the spray effect. All the paint and air mixes OUTSIDE the airbrush, just right in front of the nozzle itself. What this means is that you can only use the airbrush at a certain distance from the subject, and can only paint wide swaths at a time.

Above: A single-action airbrush and base accessories.

Though some single-action airbrushes have a paint nozzle control, and some others have specialised paint tips, people who are after finer spray lines and effects usually opt for a double-action. Single-action airbrushes are great for painting large subjects, basic spray priming, and for beginners seeking to practice using a single coloured paint subject.

Above: The single-action airbrush's only trigger.

Double-action airbrushes have dual control for 1) air flow and 2) paint flow. This is usually achieved by the trigger which controls air pressure from the hose underneath, as well as moving a fine needle back and forth to control the paint.

 

Unlike single-action airbrushes, all paint and air mixing happens INTERNALLY with a double-action. This allows users to go spray as close as possible to a subject, which lets one go even finer lines.

The base components of a double-action airbrush

With a double action, pressing full blast on air release and paint release will produce the widest width and maximum paint flow. Releasing minimum air pressure with minimum paint release will produce the finest line it can make. (This depends on the grade and engineering of the airbrush).

Needless to say, a double-action is an ideal preference for modellers, as it has the flexibility for many situations.

Click here to view the latest airbrushes and compressors from noted brand Sparmax! And here for a quick video peek!

Air Compressors

Obviously there are many kinds of air compressors available to use, but for hobby airbrushing there will be some specific requirements. Airbrushes in general need only 25 to 45 psi (pound-square-inch) air pressure to operate effectively. There are some who use their industrial air compressor capable of more than 120 to 150psi, but that is very excessive and will not only scatter paint everywhere, but will also make the airbrush hard to control!

Hobby air compressors are small, compact and quiet compared to their big brethren. They usually come in two types - one with a holding tank and one without. This simply means that the ones with holding tanks will be able to switch off their motors once enough air pressure builds up in the tank, while those without will have to keep running throughout the entire time one is using their airbrush.

The trade off for investing in a more expensive holding tank compressor comes down to not wanting continuous motor noise and power use.

Paint with an airbrush

As long as any paint can be thinned and mixed, it can be used with an airbrush. Thinners are important - the proper consistency allows the paint to flow freely through and mist properly. Long-time modellers always say to "mix the paint and thinner to the consistency of milk."

Here we see how the paint should look when thinned for the airbrush. Please note that paint to thinner ratios will vary from brand to brand.

In this video below we see how the right consistency results in the correct and even flow of paint.

Many paint manufacturers like Vallejo, AK Interactive and SMS provide paints that are ready-mixed for use with an airbrush right out of the bottle.

Click here to view how we spray flat varnishes with (and without) thinners.

Other paint brands like Tamiya, Gunze Mr Hobby and Humbrol need to be thinned with their respective thinners (acrylic, enamel or lacquer) for use. The rule of thumb is to always use an airbrush at a well ventilated area. Even if a paint is labelled non-toxic, overspray and fumes can build up and may be an hazardous.

Cleaning and maintenance

Like any precision tool, airbrushes require regular cleaning with every use. After every load of paint, the airbrush should be flushed with a separate amount of thinner until it flows clear. For double-action airbrushes, thinner or airbrush cleaner should be blown back into the internal mixing chamber as shown, which will flush any dried paint out. Click here for a demo.

Above: A top-loading cup of a double-action airbrush reveals the area needing to be kept clean after every use.

A common error among first-timers is using an airbrush for too long. Remember, even when idle, the air compressor is generating air movement and heat at the same time, which may cause paint within the airbrush begin to dry. When that happens the flow gets clogged and erratic, and bits of solidified paint may jam the nozzle, and dirty up the needle.

The tip of a double-action: The front cup protects the exposed needle tip, so don't drop it! A bent needle is rarely repairable!

For a thorough cleaning, flush the airbrush with thinners three or four times. For extreme jamming, leave the airbrush front area submerged under thinners or airbrush cleaner fluid overnight nozzle down, allowing dissolved paint to drip downwards out of the airbrush.

Above: The revealed needle assembly for a base double-action. Be careful when removing the needle entirely, as it holds a lot of trigger parts and springs together.

As much as possible, do not disassemble the airbrush completely without consulting someone with experience, as the fine needle tips and nozzles on double-action airbrushes are extremely fragile.

Stay tuned for more tips and tricks with hobby finishing products. If you'd like to request a theme or topic you'd like us to focus on, do leave us a comment below or send us an email.