Painting Model Trains With an Airbrush

Airbrush and paint

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If there is one tool that scares beginning modelers more than any other, it must be the airbrush. Perhaps it is because the thought of messing up the paint on a model is so "final" that we hesitate to try.

Rest assured, while there is a skill and art to using this tool, it can be learned without destroying your prized models. At worst, you can always strip the paint and try again if you fail.

You can do many things with an airbrush, from painting a model outright to applying weathering to a painted piece. While we usually associate it with locomotives and cars, you can use your airbrush on all parts of your model railroad. Structures, track, and scenery can all be painted or detailed with an airbrush.

When done well, the results are often faster and better than anything you'll achieve with a brush or with spray cans. An airbrush allows thinner and paint application, which can be applied over a broad area or concentrated, to create an infinite variety of effects.

You can't master the art of using your airbrush by reading about it online. Like all tools, the best way to learn is to put one in your hand and try. But to help get started, here are a few tips to help the learning process go a little more smoothly.

Choosing the Best Airbrush

Like any tool, a good quality airbrush will make it easier to produce good results. However, the hand holding the tool has a far greater impact on its performance than the tool itself. In other words, an inexpensive brush in the hands of an experienced artist is sure to deliver better results than the best brush in the hands of a novice.

An inexpensive tool does have some advantages for those just getting started. Maintenance is the key to consistent results over the long term. A simple brush is cleaned the same way as an expensive brush. Learn how to properly mix your paint and care for your tool on a cheap model before you void the warranty on a $200 tool.

Even after you've moved on to better tools, there will still be certain jobs for which those basic airbrushes work just as well. Even a basic airbrush kit is a worthwhile investment.

Paint booth for model trains
Ryan C Kunkle

Single vs. Double Action

There are two methods of controlling an airbrush: single and double action. On a single action airbrush, depressing the thumbwheel controls both the flow of paint and air.

On a double-action airbrush, you press the trigger down to control the flow of air, then pull it back to control the rate of paint flow.

There is a learning curve for both types, but double action brushes generally provide better control and results. This is especially true when wreathing models where you don't always want the same even paint coat. For many basic jobs, however, the simplicity of a single action airbrush offers an advantage.

Internal vs. External Mix

Internal mix brushes blend the air and paint inside the brush before they exit the nozzle. On an external mix brush, the air exits the nozzle and then blows through the paint.

Both of these can produce excellent results. An external mix brush does offer a slight advantage in cleaning time, but cleaning the tool is still a critical step in either model.

Compressors, Spray Booths and More

The airbrush is only part of the equation. What else do you need?

First, you'll need a source for the air. "Canned air" is an option, but it offers practically no control over the pressure, and although it may seem like a cheaper alternative than buying a compressor, it won't take long before you've thrown more than a compressor's worth of cans in the trash.

Most airbrushes operate best at between 15 and 30 psi. So you don't need a huge compressor to provide adequate air. A good compressor should have a moisture trap and a regulator to allow you to adjust the pressure. A reservoir is a huge advantage for providing a constant supply of air and for reducing the run time of the compressor. Quiet running is also a big factor, especially for apartments.

Where you paint is as important as the tool you use. A good spray booth provides a clean, organized area which reduces the likelihood of foreign matter getting stuck in the paint and keeps everything you need close at hand.

Even more important than protecting your model, a spray booth also protects you--not only the paints, but the thinners and cleaners used when airbrushing can be quite potent. A well-ventilated spray booth pulls those harmful fumes away from you.

Spray booths come in a variety of sizes and prices. A small, inexpensive and portable booth may be all you need. Do spend a few extra dollars however and get one which will properly filter and vent the fumes.

Even with the precaution of a spray booth, it is good to have a mask, protective glasses and gloves when painting.

Other helpful tools to have on hand: a turntable at the base of the spray booth for a hands-free painting of all sides of a model, paint stirrers, pipettes and pipe cleaners for mixing and cleaning, and a good light source--preferably one which mimics the lighting conditions on your layout. If your layout room has incandescent bulbs, paint under these. The change in hue provided by a fluorescent light can dramatically change the look of your model.

Mixing Paint

When it comes to using an airbrush, the prep work leading up to the job is actually more important in getting good results than the painting itself.

Most paints must be thinned for use in an airbrush. If the paint is too thick, it will clog or spray in lumps.

Different paints need to be thinned with different mediums. Even between acrylics, enamels, and lacquers, there can be differences between brands. Most brands do make a thinner designed specifically for their paint and as a general rule, these will provide good results when used as directed.​

In some cases, you can get equally good results using much less expensive materials purchased at the paint section in your hardware store. However, as stated, all paints are not created equally. Just like you wouldn't paint your car with house paints, your model paints are specially designed with properties that work best for our applications.

If you want to use large-volume thinners, then these basic rules apply: acrylics can be thinned with distilled water (some recommend mineral spirits or denatured alcohol as well), enamels can be thinned with turpentine, and lacquers with lacquer thinner.

Even if you don't use these products to thin the paint, they can be very helpful in a cleanup. A large can of turpentine from the hardware store will cost less than a small bottle from the craft shop next door.

How much to thin the paint also varies greatly with different paints. The consistency you want will also vary with the job you're doing. Thinning anywhere from 10 to 90 percent may be necessary.

If you are applying a base coat to an entire model, then you want the paint to be thin enough to flow easily but still thick enough to cover the model in one or two coats. If you are applying an overcoat to fade the paint of a finished model or trying other weathering effects, then a thinner mix will allow you to build up the effect gradually without completely obscuring the details underneath.

Airbrush thinners
Ryan C Kunkle


Believe it or not, this is the easy part!

The best way to master painting techniques is with the airbrush in your hand, not a computer. But these general tips should help.

  • Maintain an even distance from the model. Too far back and the paint won't make it or may be dry before it hits the model. (This is especially true with fast-drying acrylics.) Too close and the paint can run.
  • Use smooth, even strokes.
  • When painting a large surface, extend your stroke beyond the edge of the model to avoid fuzzy edges around corners.
  • Maintain a "wet edge" when painting. Overlap your strokes slightly and work evenly across a model from one end to the other. This blends the strokes for an even finish.
  • Gloss paints provide a better surface for decals.
  • Multiple thin coats always yield better results than a single thick coat. Because the paint application with an airbrush is so thin, a coat will dry much faster than when brush painting. You won't have to wait long, if at all, between coats.
  • Use a turntable to get all around a model. Other "fingers" and tools are available to help hold your model during painting to make it easier to get at it from all angles.
Airbrushing a model train
Ryan C Kunkle

Clean Up

Applying the paint with an airbrush is actually the easy part. Once you've finished, it's time to clean up.

Start by cleaning out the pot or jar holding the paint. Some airbrushes are designed to feed out of a standard paint bottle. If you have one of these, you can often just unscrew the bottle and replace the lid. This is great for common colors that you can premix or thin and save for multiple projects.

After replacing or removing most of the paint from the hopper, fill it with the appropriate cleaner for your paint. Cycle the cleaner through the brush until the spray is clear.

If you are spraying multiple colors, you can go ahead and start your second coat now. If you are done for the day, then it is a good idea to go a little further to make sure you've completely cleaned the brush before putting it in storage.

Disassemble the brush and soak the nozzle in​ the cleaner. Small pipe cleaners are available to clean the tubes.

After cleaning, allow the parts to dry before putting everything back together.

Cleaning an airbrush completely takes time, sometimes longer than the painting, but it is an absolutely essential task to maintain your tool and ensure good results the next time you're ready to paint. It doesn't take much to clog the tool, and dried paint is much harder to remove later.

Cleaning a model train set
Ryan C Kunkle