So you’re ready to buy that airbrush, what do you do?  Buying an airbrush today is different than it was when I was a wee lad.  In those days, your choices were very limited and, in relation to other goods at the time, they were expensive.  In fact, I knew several very skilled model railroaders who built their own airbrushes.  They were able to boast that they painted their scratchbuilt models with an airbrush that they made themselves.

Today, with the internet, it is easy to select from any number of airbrushes.  You go online and start your search.  You see many different styles and a huge difference in price.  Some of the airbrushes from different companies look the same.  Some of them are offered with options.  Now you’re scratching your head.  You go on your favorite forum board and post your dilemma.  Here is where it gets funny.  Posting a question about what airbrush to buy will instantly generate a lengthy thread.  Like so many things - cars, cameras, computers, bikes, etc. - everybody has an opinion on their choice of airbrush.  And, like - cars, cameras, computers, bikes, etc. – it can get all wrapped up in ego and misconceptions.  Not to trample on anyone’s sensitivities, but the size of your tip or how expensive an airbrush you own, is not a validation of manhood or skill with an airbrush.  A skilled photographer is able to capture wonderful images with just about any camera, because they understand light and composition.  The same principle applies to the airbrush.  I am acquainted with a very skilled, successful, published, and a bit iconoclastic, modeler, who takes great pleasure in dropping the fact that he paints his models with his trusty Paasche H.  Your success with an airbrush is going to be based more on your skill set than what airbrush you use.  This is not to say that all airbrushes are the same, they’re not, and selecting the right airbrush for the task is important, but I want to offer a framework for making a logical choice.

Selecting the right airbrush is similar to selecting a traditional paint brush.  Artists use different types of brushes depending on the type of paint they are working with and the area that they are covering.  Imagine you were going to brush paint your model.  You wouldn’t use a fine #0 brush to paint the entire model, nor would you use a ¼” flat brush for painting fine detail.  In the same way, there is no single airbrush that will be suitable for every model painting task.

As modelers, we need to select an airbrush that will work best for the material that we typically use.  The materials that any particular airbrush can handle are mainly governed by the size of the material tip.  In general, the majority of airbrushes are designed to handle relatively thin liquids, i.e. liquids of low viscosity.  Many of the finer, more expensive airbrushes are designed for artists doing close-in detail work with inks, dyes, or watercolors.  For this reason, they are always of the double action gravity feed type.  When doing very fine work, low air pressure is used to minimize overspray.  Using this type of airbrush for paint requires a bit of a dance between the viscosity of the paint and air pressure.  Airbrushes that are more suitable for handling paint have material tips with larger diameter openings.  These airbrushes are available in a variety of mix, feed, and action combinations.

When deciding on what airbrush is most suitable for your particular modeling needs it is important to step back and look at the nature of the materials involved in the finishing process.  Unlike an artist that is airbrushing ink on a porous material such as paper, we are generally using paint on hard non-porous materials.  And, unlike inks, we need to be mindful that as we thin the paint, we can in some cases, radically alter the durability of the paint as well as its ability to adhere.  How durable and how well the paint adheres is important because we may be masking or decaling over the paint.  We also need to be familiar with the different types of paint and how they may react with each other as we frequently apply layers of dissimilar materials.  I have included a brief discussion of paints here.

When airbrushing, there are three main variables that need to be controlled: Air pressure; Viscosity of the material; Amount of material.  Of these three, only the amount of material is accurately regulated by the airbrush.  Precise control of air pressure is done through a regulator and of course the viscosity of the material is controlled by preparation.  The choice of airbrush (quality being equal) should be based on the material tip size that will allow free flow of properly thinned material that is used.  This is a good criterion for choosing a minimum tip size.

Selection of maximum tip size is based more on the amount of material that needs to be applied to properly cover the area.  The first consideration is the size of the area to be painted.  For example, if the task at hand is priming a model or applying a single overall color, an airbrush with a large enough material tip is necessary to deliver sufficient paint of correct viscosity to yield a smooth durable finish.  If, on the other hand, we are using the airbrush for shading and weathering, a smaller tip would be in order.  As a general rule, I would suggest a minimum tip size of .20 mm for reliable material flow.  This is not to say that a .15 mm tip is unusable, but I think you will find that the material has to be thinned to such an extent as to render the airbrush useless for anything other than fine weathering.

For general painting, as in applying a single color over an entire model, I prefer a much larger tip size such as .40 mm to 1.0 mm.  To some, this might seem very large.  Keep in mind that what you are doing is spraying paint.  The paint needs to be wet when it hits the surface and remain wet for a short time as you apply overlapping strokes with a minimum of overspray – that area of atomized paint that has already dried before it hits the surface.  The paint needs to be thick enough to maintain its’ designed qualities of adhesion and durability.  If you are over thinning the paint and having to add a bunch of additives so that you can push it through too small of an orifice, you will not get optimal performance from your paint.  You need to have a proper volume of paint to achieve a smooth finish.  When you are applying an overall color or base coat, you are applying paint, not dust.  I have to scratch my head when, I hear about modelers who own airbrushes claim that, they get a smoother primer coat from a spray can.  That alone should be a clue that you are doing something wrong.  If the primer or paint is properly thinned, shot from the correct airbrush, with the right amount of pressure, there is absolutely no reason that you should not be able to produce a finish equal to, or superior to a spray can.  The only reason that you should be reaching for a spray can is convenience.  A have a number of airbrushes or small paint guns that I use for laying down primer or base coats.

The following video is an introduction to airbrushes and mini spray guns for scale modeling ...

When I was applying automotive finishes on 12th scale cars, I was using a detail gun which is designed for shooting jams and tight areas when painting real cars. The principles of paint application when painting a real car are quite applicable to airbrushing models. This point was strongly reinforced one day when I was painting an actual size bike frame. I was using an acrylic enamel in a full sized gun. Since I had so much paint left in the cup, I went looking for something to shoot. My victim was a 1/24th scale Monogram Nascar body. It only took a couple of passes. When the paint cured, I was totally blown away by the complete lack of orange peel and the preservation of detail. In fact, I had forgotten that I had sanded the roof and every scratch mark shown right through. So when you are applying a primer, base coat (especially a gloss finish) volume is extremely important. This is especially true for models with tiny details that might get obliterated if you were to wet sand the primer. Also, consider that your primer or base coat is the basis for all your future paint and decals. If you can’t wet sand, then that first coat needs to be as smooth as possible. So don’t reach for that derelict old airbrush “that I only use for primer.” Primer doesn’t need to have the texture of 320 grit for the paint to adhere. When you take that up close image of the canopy or nose of your model, you don’t want to be looking at grain.

The Iwata RG-3 is on of the most popular large airbrushes.  This video is a guide to setting up the Iwata RG-3

This video has some tips for how to paint scale models with a miniature spray gun.

This video presents information about the fan pattern of mini spray guns for painting scale models.