The airbrush can be described as a "mechanical paintbrush". By placing paint in an attachment to the airbrush and then applying some kind of air pressure, the modeller can achieve anything from pencil-thin lines of colour, to uniform coverage of broad areas. Subtle tonal gradations are easy to achieve, and the modeller or artist can mix their own particular paint shade to produce any colour scheme.
The most basic type of airbrush is an external mix spray gun. These are usually syphon fed with air blown through the brush and over the paint outside of the brush. The spray is less fine than most airbrushes. Internal atomization type of airbrushes (where paint and air are mixed inside the airbrush) are more common. In a simple single-action airbrush, the trigger can be pressed for air and the amount of paint (i.e. width of spray) must be preset by adjusting a knob on the end of the airbrush body. In the more complex double- action type, both air and paint flow through the airbrush. The trigger can be pushed down for air and pulled back for paint, controlling the ratio of paint to air and allowing the artist to control the width of the spray while painting.
The air pressure can be supplied through a variety of means. Cans of compressed air are silent, easily portable, simple to use, inexpensive for occasional use but for regular use are expensive, and the air pressure goes down as the can gets empty or cold. Compressors are more commonly used and can include the following types:
1) Diaphragm compressor which uses a diaphragm to pump the air into the compressor and out the airbrush and is the least expensive type of the compressors but the diaphragm produces a pulsing of airflow that can sometimes be seen in the artwork.
2) Piston compressor uses a piston to compress the air. It does not have the pulsating quality that the diaphragm type has but the oil that is used to lubricate the pistons can get into the airbrush occasionally and it can overheat if used for a long period of time.
3) Storage compressor contains a reservoir tank for the compressed air, so that pulsing does not occur through the airbrush but the simple types run continuously and can overheat.
4) Automatic compressor types use a reservoir. When the reservoir is filled to a certain preset pressure, it shuts itself off automatically. When pressure drops below the preset level during use, resumes filling the reservoir. The plusses include silent operation, even pressure and that the motor does not run constantly so reduces chance of overheating but the machine tends to be very expensive.
Other air sources include CO2 tanks (with pressure regulator) which are silent, refills are inexpensive and can go for quite sometime before needing refill but you need to buy a pressure regulator to use with tank since pressure straight from the tank is too high for an airbrush and the tank is heavy- definitely not portable. Car tyres are cheap, you can pick up a used one just about anywhere. They can be refilled and reused often and are silent but pressure to airbrush will drop as tire deflates and constant refilling is needed; the tyres are often dirty and hard to clean.
After selecting an airbrush and source of air pressure, the first thing for a beginner to do is to practice mixing a diluted paint/thinner mixture that will flow evenly from the airbrush. Generally, a thinner mixture is needed compared to that of brush painting. The combination of thinned paint, air pressure and nozzle setting of the airbrush has to be determined for each application. As more skills are learned, the modeller will be able to use the airbrush to create very accurate looking paint finishes on any type of model.
A periodic airbrush cleaning is necessary (some modellers prefer to clean after each use) . Often spraying a solvent through the airbrush is all that is needed but a breakdown of the airbrush can help eliminate problems of paint buildup. Useful solvents to clean an airbrush (after taking it apart) are methyl hydrate (commonly used solvent) or lacquer thinner (great for stubborn cases but be careful as some airbrushes have internal seals that would be affected).
Previous Lesson: Presentation and Display of your Model
Next Lesson: More Advanced Model Building Techniques