Brushing up!

Brushing up!

The fruits of my labours, not perfect I'll readily confess but far better than I had expected

Airbrushes have always been at the periphery of my aeromodelling vision. As a kid I grew up on a staple diet of Airfix kits so should really have had an airbrush a long time ago. I think I've always dismissed the possibilities of ownership on three grounds – cost, technical know-how and artistic ability. I've assumed that airbrushing is an expensive pursuit for which you need tons of cash, a degree in chemistry and must possess artistic flair in spades to do any justice.

My first encounter with an active airbrush was way back at the 1979 Pontins Model Festival in Somerset. There I watched the great airbrush impresario himself, Ian Peacock, putting a figure of a Scots Highlander on the side of Len Mounts huge (for the time) Bucker Jungmeister.

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I've painted models of course, especially foamies from the likes of GWS or Multiplex albeit using spray cans to cover large areas. This in itself is quite limiting, especially with regard to the degree of artistic licence that can be used, so, eventually, I decided to bite the bullet and go in search of some help. Getting to grips with an airbrush was something I'd need to learn. It was time to go back to school.

AIRBRUSH DAY

Modelling airbrush courses are run by a number of companies across the UK, and the nearest I could find here in the deep south were by The Airbrush Company Ltd., who are based in Lancing, West Sussex. The company sells airbrushes and all manner of accessories at www.airbrushes.com and, at the premises, they've set up a classroom facility that accommodates up to eight students, each with desk and airbrush station. Perfect.

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Robin made it look so easy…

Greeted by the Airbrush Co.s Alex Medwell, on arrival I was shown around and introduced to my fellow students and course tutor, Robin Carpenter. Robin may need no introduction to some as hes been painting full-size warbirds for many years. Clearly, we were in good hands, and rarely have I learned so much in a single day.

BRUSH TYPES – SINGLE OR DUAL?

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Robin began by talking us through the different types of airbrush and how they operate. Believe it or not, you can paint with any liquid using an airbrush: the result will simply depend on nozzle size, liquid density and spray pressure. That makes sense, but airbrushes come in many shapes and sizes. The basic principle is simple – air is forced from a compressor through a tube that's blocked by a needle. The needle is connected to a trigger that retracts it when depressed. With this the high-velocity airflow is allowed to pass through, atomising the paint on its way, the latter drawn from an adjacent reservoir. There are two types of airbrush:

Single action: A trigger moves up and down to get paint immediately; flow adjustments are made at the back of the brush. Cheaper airbrushes tend to be of this type.

Dual action: The degree of trigger depression regulates the flow of air and paint: depress the trigger, air starts coming through. Press a little harder and the paint spray will start – the more pressure applied to the trigger so the more paint will come out and the spray size will increase.

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There are two factors that affect all this, though – nozzle size and air pressure. Nozzle sizes vary according to the type of work being tackled, although I've used a 0.5mm nozzle throughout and have been happy with the results. Incidentally, I'm told that this is a good average size, common to many airbrushes.

Here's the set-up, it's really not as bad as it looks when you start using it

AIR SUPPY

An air supply at constant pressure is vital to the process – variable pressure will result in a correspondingly variable paint finish! Although some modellers have used (would you believe) car tyres to supply air, it should ideally come from one of two sources: a canister or a compressor. Canisters are cheap but have the disadvantage that they'll probably expire at the wrong moment, leaving splodges on the work as the paint splutters through. The air supply can also vary, which again will inevitably be at the wrong moment. Compressors are more expensive but ensure a constant supply is provided to the brush at all times. Compressors suck in air, squeeze it and spit it out into the airline and onwards to the brush. There are two types: Bleed-off and Basic. Bleed-off units will literally bleed off any undesirable moisture thats captured, via a little valve; Basic units won't do this and, as such, tend to push room air into the brush.

I decided to follow the compressor route and went for a basic bleed-off type – an Iwata Sprint Jet. My choice was guided by Alex, and I'm very pleased with it. Fitted with a long air line to the brush itself, my compressor is very quiet and happily purrs away in the corner of my workshop almost unnoticed.

Most compressor units have a pressure gauge that measures the flow of air to the brush. The gauge on the Sprint Jet indicates PSI (pounds per square inch), and I've employed 15 – 20 PSI for small areas such as camouflage spots and 20 – 30 PSI for larger pieces of work – where a whole wing needs painting, for example. These are just guides, you understand – having had a bit of experience I now tend to adjust the valve without looking at the gauge, taking a reference from a test spray.

These are the water based paints that I used along with the Tamiya acrylics…..

PAINT FEED

Paint is fed to an airbrush from a paint cup, which is normally mounted on the side or on top of the brush. There are a number of types: gravity feed, bottom feed and side feed – named after the cup position – and all have advantages and disadvantages. I was surprised that the cups are often simple push-fit affairs on even the most expensive of units; suffice to say they all work well, although my favourite is the stainless steel gravity feed cup supplied with my brush. I've used the simple push-fit bottom feed plastic types as they allow quick colour changes, but in my opinion the custom-made Iwata cup seems to do the best job. Being gravity fed it requires a little less air pressure, too. Some argue that the gravity cup can obscure the modellers view but I would assume this is only a problem with small-scale static models, as it certainly hasn't troubled me.

CLEANING UP

One of the most important things Robin demonstrated was how to disassemble the brush for cleaning. Many modellers are put off by the thought of cleaning an airbrush to the extent that they avoid airbrushing altogether. In practice the cleaning process is pretty straightforward – more time-consuming than using an ordinary paintbrush, of course, yet hardly sufficient to put me off the process.

I'm told that white spirit is the best cleaner when using enamels, although to date I've only painted with acrylics and have found the dedicated bottled cleaning fluids and reamer spray to be perfect for the job. I do tend to get through plenty of paper kitchen towels in the process, mind!

….and these are the cleaners, the foaming spray seems particularly effective

PAINT

Our course familiarisation session was conducted using watered food colourings before we moved onto the serious stuff. Although enamels are still used, water-based acrylics are now becoming increasingly popular. For a start they're safer from the respiratory point of view and providing a good undercoat has been established and a good top (lacquer) coat is added they should wear well (fuel-proofing considerations accepted, of course).

There's one vital point to mention here, and that relates to thinning. Many paints, for instance Tamiya acrylics and the Auto-Air colour range, are supplied ready to be used straight from the bottle. They can be easily mixed, but as far as thinning is concerned, these water-based paints should only be thinned with water to a maximum of 25%. Water breaks down the molecular structure of acrylics beyond this, so if you wish to thin at higher percentages, be sure to use the thinning product recommended by the relevant paint manufacturer.

One advantage of water-based paints is that they can be dried quickly using a hair dryer. Some paint packaging states that spraying acrylics should be in temperatures of 70°F or more, and given that spraying is likely to be conducted in a shed or garage, winter doesn't seem like the best time to paint. In practice I've not had a problem and tend to warm the garage up before painting, although I've avoided spraying when there's a lot of moisture in the air.

There are some little-known paints around that are excellent for R/C aeromodelling purposes. Robin demonstrated the use of Alclad, a metallic acrylic paint that must be just about the nearest thing to a metal finish I've seen without using metal! The Alclad range covers most metallic finishes and would be perfect for that scale P-38 or P-51 project.

MASKING

Plastic kit modellers and scale modellers rarely use DIY-type masking tape on their models, and I can see why – it's just so horrible in use and inevitably leads to poor results. On the course I discovered some of the new low-tack plastic films now beloved by plastic scale modellers. Ultra Mask is something I've since had a lot of success with. Its a soft, clear, sticky-back film that's slightly stretchy and leaves a perfect edge. It's supplied in sheets and can be used for basic masking or for lettering and markings. Being low-tack it never removes or damages the underlying layer of paint. It really is superb, I'll never go back to the old paper masking tape.

The metal paint cup worked best although the cheap plastic cups mean that colour changes are quick and easy to perform

GUINEA PIG

And so to my first airbrushing project, the GWS FW-190. Surface preparation is vital with any model, whether it flies or not, and this park-fly foamie would be no different. In truth, and as the building progressed, I found myself worrying that the surface quality wasnt good enough and that the foam nature of the beast would be all too apparent. However, with the model now complete I'm pleased to say that the various layers have covered very well – far better than the results afforded by the DIY spray cans Ive tended to use in the past.

To finish the '190 I used water-based acrylics from Tamiya and Auto-Air, straight from their containers. The great thing here was the lack of wastage; the spray from the brush is so controllable so it goes where required.

The scheme, like the model itself, is loosely based on an FW-190A-8 flying on the western front in 1944. As a first attempt my aim was to get a good finish rather than attend to a pure scale interpretation of the aircraft.

I started with an off-white base coat, mixed visually and poured into the side cup as required. This saved paint, but I had to get the mix right as variations in colour can be all too obvious when the paint dries. I painted the upper surfaces of the wings and tail in light grey and then added the darker grey wing camouflage by masking with a hand-held piece of paper, which produced a nice edge.

These early airbrush ventures were punctuated by stoppages and delays as familiarisation with the brush steadily improved. There's definitely a knack to all this which, of course, comes with practice. Whilst I'll be the first to admit that I need plenty more of the latter, I was rather pleased all the same.

Most of the time I used hand-held paper to mask the lines, albeit with Ultra-Mask tape on canopy glazing

Before starting the FWs paint job a friend told me that I'd probably struggle with a dual action unit, but this wasn't the case. I found that maintaining a constant trigger pressure (and therefore spray size) was perfectly easy to achieve.

I sprayed the top of the fuselage in light grey, applying the paint by eye, and then went along adding the dark grey camouflage splodges. The canopy glazing had been masked off with Ultra Mask before of course. All that remained was to make a paper mask to hold over the cowl as I painted the exhaust outlet with a mixed red / rust colour followed by some black, in an attempt to simulate the exhaust residue of a full-size aircraft.

LET US SPRAY?

Sometimes you achieve something that youre very pleased with, irrespective of what others may think… and I'm dead chuffed with the finish on my FW-190 – warts an' all. There's a long way to go and I'll readily admit that I'm still on the learning curve, but buying an airbrush and attending class is something I wish I'd done years ago. Bring on the foamies!

David Ashby

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