Staining A Natural Metal Finish

My philosophy as a contributor to Airfix Model World magazine, has been from the outset, to create and illustrate methods that adhere as closely as possible to ‘Occam’s Razor’. In other words to seek and promote the simplest solutions to a modelling task. I’ll accept that my employment of that philosophical principle takes a few liberties with its strict meaning but it remains the case that ‘the simplest solution is usually the best’ is still the most generally understood translation.

And so it was with that area of paint finishing that sometimes causes considerable anguish – ‘NMF’ as it is commonly abbreviated or a ‘natural metal finish’. A well trodden favourite approach for varying such a thing is to pluck different shades from the shelf, mask off ‘selected panels’ and pretty much leave it at that. Perfectly fine to my mind – it adhere’s to ‘Occam’s Razor’ and is accessible to anyone with basic control of an airbrush or ‘hairy stick’ but there’s also scope for a properly variegated finish that imitates the kind of staining that lifts the NMF to an altogether more realistic level. And it’s simple.

You’ll need a model (Jedi master of the absolutely flippin’ obvious me). This was my choice, Tamiya’s 1/32 P-51D Mustang. Please ignore the ‘grey’ puttied wings (or see ‘My Tuskegee Hero’ for more information – AMW USAAF ‘special’ ) and focus on the fuselage in fresh Alclad II Aluminium ALC101. I did sojourn in the land of ‘mask and darken’ by doing just that for the panel under the exhausts, that photos often show as such.

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From there, the weathering road forked left and a tube of Michael Harding Lamp Black oil paint was deployed. Why ‘Michael Harding’ (MH) and not ‘that other brand everyone’s heard of’? Like ‘Occam’s Razor’, it’s again simple – MH has hand ground pigments that are extremely fine and outperform courser (and cheaper) mixes elsewhere. In this application, that propensity to mix with artist’s quality white spirit (mineral spirits in the US) results in creamy washes and is exactly what’s required.

A medium strength wash, comprising a pea sized drop of Lamp Black, married to three full eye dropper loads of that artist’s quality white spirit was made up. With the safety catch ‘off’, the model was held by the starboard wing, with the port fuselage side uppermost. A quarter inch round brush was dipped in the wash and fully loaded. 50% of that load was allowed to wick away by touching it to the side of the plastic mixing dish. From there, the brush tip was touched or lightly dabbed on the horizontal fuselage surfaces, some half  inch to an inch or so apart. There was no attempt to paint the wash on with strokes. Instead, small quantities were just touched to the surface and the wash was allowed to migrate outwards.

Applications would collide and mix, giving further variety of totally random staining. I guess six to a eight dabs were put on at a time and once spread, given a little accelerated drying with a hair dryer held far enough away so as not to blow the wash. No wash applications were made directly into panel lines. Some wash moved into panel lines and other detail but this was left to occur randomly. The model was sometimes tilted to adjust wash flow, as the port side was covered until the whole section was complete.

All that then remained was to flip the model so the starboard side was horizontal and the process could be repeated. Ditto the topsides and lowers, followed by a critical examination of wash distribution. Where it was deemed to heavy or insufficiently random a latex free gloved hand meant errant portions could be dabbed with a forefinger ‘pad’ that lifted a little paint (cleaned off on tissue before resuming) – the glove texture transferring to the model and adding to the effect. In tandem with this, marks could (and were) removed with an ordinary pencil eraser before tiny repeat washes back filled and completed what I was looking for. Last step on step one was to seal progress by drifting a light mist coat of Tamiya matt clear, cut with cellulose (lacquer thinner in the US) and to blow dry with the hair dryer. Here’s step one complete.

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Step two was a straight repeat of the above, again sealed as before.

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In the second pair of shots things may not have appeared to have changed much but the principal ‘gain’ is in panel line and detail definition. It’s in no sense ‘black’ but merely grey, exactly as was intended at the outset. The reward for this simple technique was the variegated staining I’d wanted and the resulting contrast with those grey wings was very much as exemplified by the Hendon Mustang.

On the flight line.

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Wish you well with it, if you give it a go. 🙂

Until next time.

Bad Wolf

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