During my first modeling career fifteen years ago I was very interested in subjects from World War II, and I kept being tied to this era even in my job as a legal historian. But after years of professional occupation with this time my fascination started to wear out, so when I rediscovered my interest in scale modeling it was clear for me to avoid anything earlier than 1945 and to concentrate on more colourful subjects, and what is more colourful than the gaudy markings of jets from the 50s and 60s? Since these were mostly painted on the bare metal skin of the planes I had to deal with the problem of recreating a realistic-looking metallic finish on plastic surfaces. Unfortunately my living space is very limited, which is typical for central European conditions, my dining table in the living room being the only place where to model, so the use of an airbrush was totally out of question. Being technically limited to simply paintbrushing all of my models I developed a painting technique which – although maybe not as good as would be possible by using an airbrush – nonetheless results in a rather presentable bare-metal finish. This is how it works:
Which paints to use
There are many different metallic paints on the market, I am using Humbrol's METALCOTE paints, mostly "Polished Aluminum", "Flat Aluminum" and "PolishedSteel". The single reason why I decided to use these paints was that they were the only metallic paints available in my town. In the meantime I have discovered the advantages of mailorder companies and so I could now use many alternative products, which sometimes even don't have some of typical shortcomings of the Humbrol paints, but I am used to them and – "never change a working technique"!
The following procedures may sound very complicated and their description might be suitable to deter interested modelers from trying them, but please believe me that all this is nothing but routine which won't take more time than, say, a three-tone camouflage scheme of normal complexity.
Preparation of the model
It is well-known that metallic paints are very thin and will enhance any structure on the model's surface, especially of course any faults which might have been overlooked before painting has started. So it is essential to prepare the plastic surface to be as smooth as possible. I do not use any primer before applying the Metalcote paint, since I am very anxious that painting the primer could introduce fine brushmarks which will show through the metallic paint, so I prefer painting the metal paint directly on the plastic. Before doing this I fill and sand any irregularity such as seams, sink holes or rough spots. Sanding procedure is boring of course, working in several steps from the roughest grit down to the finest, which in my case is 1200. Then the plastic gets a polishing with my powertool; I use a stronger polishing wheel together with a polishing paste. Work carefully with low turning rates, since the friction at high speeds can melt the plastic. The result of this procedure is a perfectly smooth surface. Of course nobody is perfect, especially not me, so sometimes I discover only after application of the metallic paint that I have not been good enough in removing all irregularities; a fine seam or something similar might show through. In that case: Return to field 1 and start all over again. Or leave it and hope that nobody will notice.
After the plastic surface has been prepared I apply the paint directly from the tin, since the Humbrol Metalcote paints are very thin already. I use a large, soft brush, painting with long steady strokes. After the upperside is finished I let it dry for about an hour, then paint the underside. This sounds as easy as it is, but as always there are some points which should be taken care of: As long as the paint is thin enough no brushmarks will appear on the painted surface, so keep in mind to dip the brush into the paint often enough. Sometimes it happens that the brush loses dust particles or even hairs in the paint you just applied, which of course is very annoying but unavoidable as long as one is forced to use a brush. In that case, keep a pair of tweezers ready to remove those particles immediately. Don't paint over that spot now, otherwise you will get visible brushmarks. Leave that damage to the second coat.
There is the clue: the second paint coat. If everything worked fine with your first coat of paint you might believe that it is perfect as it is, especially if you are lighting your workspace with some direct lightsources, such as halogen spotlights. But as soon as you switch off those lights and inspect your model in ambient daylight you will find that there are many spots where the plastic is shining through the paint. The reason for the wrong impression is that the metallic particles in the paint reflect the direct light so well that the reflections are overshining the spots where the paintcoat is too thin and therefore not perfect. So it is better to apply the paint without direct lightsources whenever possible.
Let the paint dry for at least an hour before you apply the second coat. If you do that too early you risk lifting off the first coat from the plastic, smearing it into the brush and so leaving very nasty brushmarks. Before painting the second time, check the surface for dust or brush hairs, lift them off with tweezers and sand down the resulting rims very carefully with fine sandpaper.
Please keep in mind that many metallic enamels cannot be overpainted with normal paints except on very small spots such as antennae, gun muzzles or similar items. The other paint will not adhere to the metallic ground, so you have to carefully plan your painting procedure to ensure that the metallic paint is the last one to be applied. Any other-coloured details, for example fins, wingtips or air intakes which often are brightly coloured on 50s and 60s jets, have to be painted first and then masked off appropriately.
Normally a jet aircraft does not consist of the same material overall, but is merely a composition of different alloys. Additionally, some segments might be exposed to heat or acid liquids. This results in a multi-hued look for any bare-metal plane which is serving for a time. For a good model it is essential to reproduce this "patchwork-look", so several panels have to painted with differing shades of metallic paint to appear somewhat darker or – when heat-treated – a bit browner than the rest. The main problem here is the common wisdom that – with one exception – metallic paints cannot be masked. Well, this is certainly true, since any masking tape or liquid applied on the metallic paint will lift off a layer of paint pigments when taken away, leaving a much brighter spot where it has been. If you are good enough you can overcome this by painting the panels freehanded, without masking them off. With a bit experience and a small brush this is not too difficult, using the raised or engraved panel line as a guide. But sometimes I do mask off some panels, using a liquid mask as Gunze's "Masking Sol", because afterwards it is easy to polish out the marks left over from the mask.
To differentiate the panels, I mix drops of various grey or yellow/brown shades into the original aluminum paint. Just remember that the originally bright silver appearance of the pure aluminum paint will darken considerably when polished, so the contrast between the darker panel and the rest might disappear after polishing. Therefore don't hesitate to seemingly overdo it a little bit with the drops of grey. Only experience will give you the right formula, and even then it is possible to make some mistakes: On the F-84F and RF-84F models depicted I got the subtle differences perfectly right, but when I photographed them under direct light, they seem to disappear. On the other hand, look at the F-86 "Sabre": in the pictures the different panels look realistically coloured, but in reality I have added some drops of grey too many, so the differences are not so subtle as they should.
Without any further treatment, the Humbrol Metalcote paint "Polished Aluminum" will result in a nice silvery look which reproduces any plane surface painted with aluminum colour. Just think of the "Mustang's" wings or the wheel wells of many planes. Have a look at the MiG-21MF with the nose art depicted in this picture.
The original Czechoslovak AF "Fishbed" has been painted with aluminum colour, so I left the model as it is, without polishing it. In contrast to this the earlier MiG21FL of the Indian AF definitely was left unpainted, so I polished the model in order to give it the metallic appearance – it is hard to spot quickly that both models were painted with the same paint.
Polishing is made again with the help of a powertool, this time with a very soft polishing wheel. This is a very boring work and each time annoying my wife who tries to follow her TV film next to that, but don't try to speed things up by increasing the turning speed of the wheel! The friction heat might melt the plastic, additionally there is the danger that any edges, such as leading and trailing edges of the wings "catch" the wheel which then is producing a nasty rim on the edge. So try to hold your hand steady, frequently change the orientation of the polishing wheel in order to get different sheens from the panels and work yourself systematically through the wings and the fuselage. The result you get from this method is magnificent, almost mirror-like and definitely metallic-looking. The paint surface is very prone to fingerprints, so I wear surgical latex gloves whenever I handle the model.
When asked if bare-metal finishes should be sealed with some gloss coat, nine of ten modelers will advise you not to do that. I am the one giving another answer: It is said that every gloss coat applied on the polished metallic paint will dull the mirror-like appearance you invested so much work into. I agree, this is correct, but is it so wrong? The only bare-metal jets which really look like mirrors have been those presented during rollout ceremonies, the "Thunderbirds" and maybe those planes which flew under the ever-sunny and dry skies of California and Nevada. But in the moisture of South-East Asia and the clouds of Europe every unpainted metal surface oxidizes and therefore becomes dull within months, if not weeks. If you look at the pictures from the Korean War, you will most likely find the jets depicted to be weathered, their metallic finish being rather flat or dull. So if modelers try everything to appropriately weather their planes, why shouldn't they do the same with bare-metal finishes?
There is another - for me even more important - aspect of sealing the finish: I do not have the luxury of display cases for my plane models, so they have to be frequently taken out from their shelves in order to dust them. The metallic paint coat is soft, so dust particles roughen it; every handling without gloves leaves fingerprints, and every handling with gloves will wear off some of the paint, especially on the leading and trailing edges where you are most likely to grab the model.
Therefore I seal all my models with floorwax which has proven to be the best way to do that. Since we do not get the renowned "Future" here in Austria, I have done some research in order to find alternatives, and I found that most floor-polishing liquids, like those produced by the Henkel company, will do the job as well. It is important that they are thin enough not to leave any visible brushmarks. Since the wax coat dulls the metal finish it also further reduces the contrast between the differently coloured panels, so this should be taken into account when mixing the paint for them. Always try out the wax on a surplus part you have painted and polished before, because sometimes – either due to the age of the floorwax or themoisture in the air, or the water in the brush, or whatever else – the coat will not dry glossy, but nearly flat; this has to be avoided of course. Unfortunately it happened to me once, on one of my favourite models, the 1/48 MiG-15 from Tamiya. Even when I applied a second coat of another floorwax, the finish stayed flat. The rescue came in the shape of an article in the rec.models.scale-newsgroup which translated a passage from a new Russian book on the MiG-15. There it said that the MiGs where not in fact left bare-metal, but painted with some kind of aluminum paint which weathered into a flat appearance quickly. Taking this into consideration my MiG might be looking perfectly right, who knows?
I apply the decals over the wax coat, then the decals themselves are sealed once again in order to keep the dust from working its way under them. If applied correctly, the gloss coat even will give the finish a deeper sheen, not limited to the uppermost surface, but adding a bit of depth which is does not look bad to my eyes.
I hope this shows that we brush-painters don't need to be desperate about our technological limitations, especially when making bare-metal finishes. I even think we are not slower than our airbrush-equipped colleagues, since we save the time they need to mask off canopies, wheel wells etc. The polishing work afterwards is the same for all of us.