Ask Phil: What use is a cheap airbrush?

02 December 2020
I've been given one of those really cheap airbrush sets as a present. Should I just hide it at the back of a cupboard or is it useful? Brian, Settle.

The well-meaning gift from a non-modeller? Don't worry, there's no such thing as a useless tool. You just need to be realistic about the capabilities of the equipment you now own. 

What you have is an "external mix" airbrush. That means the air and paint that make up the spray, are mixed outside the body of the tool. In this case, by blowing air over the top of the paint pot. As the air crosses the nozzle on the pot, it draws the paint mix up where it mixes with the air, becoming the mist you paint the model with.

Being realistic, this isn't the tool for high-quality locomotive repaints. You can't control the mix much and the atomisation isn't great. With airbrushes, you get what you pay for, and this is a cheap tool.

However, not every job requires all that a pricier airbrush can do. Much of the time, we just want to mist a coat of dirt on a model, and here, the cheap version will work.

This tank wagon was given a light mist of earthy brown colour. The enamel paint was thinned 50:50 with white spirit and, after a little practice, a reasonable result is achieved. I've certainly seen the so-called "factory weathering" that looks like this! A little work with weathering powders once the paint has dried will produce a creditable model.

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You can also mist colour over the scenery. Adding a very thin coat of grey over the whole layout brings the colours together in a harmonious way. Expert modellers even vary the level of this to simulate distance -  in the same way that when you look at a view, it appears to be greyer and lighter in the distance than close up.

One big advantage of the external mix tool is that it needs very little cleaning up after work. The paint pot should be washed out, but there aren't many tiny passages to be cleaned as there are with more complex tools.

An issue you will face is that the kit normally arrives with a can of air. In theory, this is great. Connect the can and you are ready to go. Sadly, the pressure drops off a lot as the can empties. Partly, this is just because there is less air, but also it cools, and that reduces the pressure further. 

The solution is simple. Stand the can in a bath of hot water while you work. It doesn't need to be boiling, but hot enough for washing up. 

Of course, the can won't last forever, and replacements are expensive. If you plan on much airbrushing, a cheap compressor will be a wise investment. For the moment, your new tool is a step up from an aerosol can of paint and will give you a feel for painting this way - if you enjoy it, then the time has come to upgrade your equipment.

One important point. ALWAYS wear a suitably rated face mask while spray painting.

Do you have a model railway question - send it in and we'll answer it.