The BRM Guide to Airbrushing

Despite what many think, airbrushing isn’t some strange dark art. When you simplify it, you’re literally firing atomised paint at a model. There are only three variables to work with – air pressure, paint volume and paint consistency. Your choice of airbrush should match your application, too – some are more suited to fine detail work, others for spraying large backscenes or terrain.

Airbrushes come in a variety of shapes and sizes. An airbrush is an investment and must be treated as such. Many cheap airbrushes have seals that deteriorate through exposure to solvents and lack the availability of spare parts or interchangeable components.

This duo of airbrushes from Harder & Steenbeck is an excellent all-purpose choice for the discerning modeller. The manufacturer also produces interchangeable needles and nozzles, compatible with the models to enable finer and more precise spray patterns, or wider and more general-purpose patterns from the same airbrush, saving on your investment. Either of these airbrushes can be considered as single purchase items because of the availability of spares, making repairs straight-forward and avoiding waste. Their seals are long-lasting too, providing you use the correct lubricant when in use. The Evolution is a no-nonsense model, supplied with a 2mL and 5mL cup, though side-feed systems have been available, too. Its Infinity is also supplied with a 2mL and 5mL cup, both with caps to prevent paint from leaking.

Keeping your airbrush maintained is as important as learning how to airbrush. The needle, cup, and nozzle must be thoroughly cleaned with an appropriate solvent or cleaner after each use to prevent the build-up of paint. Most airbrushes are dismantled in a similar fashion, by unscrewing the rear of the unit and unscrewing the needle clamp. In the case of Harder and Steenbeck airbrushes, the same method is used when changing needle sizes, too.

The needle of an airbrush and its adjustment is one of the key features when airbrushing. It is a fragile component and should ideally be protected by the use of a nozzle to prevent scratching the surface of your work, or worse still, bending the needle. Pulling back the trigger of the airbrush retracts the needle into the body of the unit, increasing the flow of air and paint. The further the trigger is pulled, the more the air and paint mixture will be released. Better quality airbrushes feature a two-stage air/paint release, where the air is released from the nozzle when the trigger is pulled back a little before the flow of paint is introduced. This reduces the tendency for paint to splatter on the work and helps provide a better finish on models.

Whatever the type of paint you choose to use through your airbrush, it must be thinned to the consistency of milk for best results. Under-thinning it will force it to splatter; over-thinning it will make it pool or worse, run on your model. Acrylics, enamels, or two-part paints with activated thinners are the most common types of paint you’re likely to encounter, but you must ensure that these are thoroughly mixed without lumps. Be wary of dried paint debris from the edge of the paint tin lid.

Masking is an essential part of airbrushing. You can’t expect to rush or skip over this step and obtain great results. Simply put, airbrushing will fire paint across a wide area and you’ll encounter a phenomenon known as ‘over-spray’. This can be problematic if weathering locomotives because you’ll spray everything - glazing included. Modellers’ fine masking tape, such as that by Tamiya, can be used in conjunction with a masking fluid-like Humbrol Maskol to good effect. 

Work from a distance of about a foot when respraying a model, or half that when spraying detail parts with the flow of paint reduced. Spray your work using a methodical approach, avoiding an excessive application, leaving a sufficient drying time. From model scenery to locomotives or rolling stock, airbrushing is a very effective weathering technique and can be used to great effect. Follow these steps and you’ll make great progress.

Need more advice? Take a look at the BRM Techniques page for all our latest guides and advice articles.