Tech Tips
by Urs Bopp, IPMS Matterhorn Circle
A common finish to many interesting aircraft of the World War II and 1950s era is natural metal. Producing a convincing look of a metal surface on a model is widely considered to be the hardest finish to get right. During recent years, this has resulted in a proliferation of new painting products which are supposed to ease the task – various metalizers, polishable paints, aluminium paste or powders, Alclad, you name it.
In this article I will review a method which I have been successful with, and which is based on ordinary no-nonsense paint techniques. It is well-suited for representing oxidised (weathered) metal surfaces, typical of the aircraft that have had their share of field service. New or highly polished aluminium aircraft would require even more shine, and for that you would probably need to revert to other paints and techniques.
The basis for this technique is Humbrol’s classic No. 11 Silver enamel. Using such an ”ordinary” Humbrol paint to reproduce metal finish may sound outdated and unglamorous. Rather than going into discussion whether we need more modern products on the market, I’ll rather let the model images speak for themselves and leave it to the reader to make the final judgement in this matter.
The paint
The basis of my silver finish is Humbrol enamel No. 11 Silver. Humbrol produces also another silver shade, called No. 56 Aluminium. The latter is in my opinion too dark to use for natural metal finished aircraft. However, I frequently use it to paint aluminium casting parts like undercarriage legs, since cast parts usually look darker than rolled aluminium plate.
To obtain different shades of silver, Humbrol No. 11 can be simply mixed with gloss black or gloss white. For example, the silver shades I used for my 1/72 Ki-61 Hien are:
- Humbrol Silver No.11
- 1 part Gloss White No.22 mixed with 5 parts Silver No.11
- 1 part Gloss Black No.21 mixed with 10 parts Silver No.11
- 1 part Gloss Black No.21 mixed with 5 parts Silver No.11
Before spraying the aircraft I usually make a plan for the application of the different shades (see the attached file), to make sure no two attaching panels have the same shade.
Airbrushing
I paint the model like the original: starting with the silver and then applying the other colours.
Airbrushing is the order of the day. For Humbrol paints I only use Humbrol’s thinner, approx. 50% paint to 50% thinner. Usually I give it a try at an old model and the add some thinner if necessary.
I set the pressure to approx. 2 bar for my Olympos HP-100B airbrush.
I usually spray only one layer of paint (per silver shade). That’s all there is to it!
Like with other Humbrol enamels, the painted surface should be left for at least 24 hours to dry. I usually start masking for the next shade after a day or two, and then the masking itself takes quite some time… so it is not unusual that it takes several days until I airbrush the next shade.
Quality of the finish
The big advantage of Humbrol’s silver surface is that it is rather strong (at least for a silver paint). There is no problem with fingerprints, paint wearing off, or masking.
Although masking is generally no problem, I take some extra precaution when masking silver surfaces just in case. The first rule is to use a god quality masking tape. Before application of a piece of tape, I first touch it with my thumb to make it less sticky.
After painting, masks should be removed gently. Depending on how tacky the tape was, it has happened that flakes of silver paints came off with the paint. You can prevent it by making the tape less sticky, see above. Or if you dare, you can use this effect to your advantage. Since I’m often after the look of more corroded metal aircraft (like Japanese planes), this tearing-off gives a surface a naturally aged look.
You can paint over the silver-painted areas with other colours. Some extra care should be applied as the paint doesn’t adhere so strongly to the silver paint as it does to ordinary ”solid” coloured surfaces.
Clear-coating and decals
I never polish or clear-coat a natural metal finish. I leave it as it is.
When applying decals on top of the metal surface, I trim the clear decal film. In fact I do it with any brand of decals. I was never satisfied with the outcome when I left the decal film intact. I even started to make silk screen stencils in order to avoid the decals altogether.
Final words
I found that the described method has many virtues. It is reliable, and gives a convincing metal finish within the limit of one’s ordinary painting techniques. That said, I am constantly experimenting with other paints, too.
I have also tried dedicated metalizer paints like Gunze Sangyo’s Mr. Metal Color with success. However, these paints are very delicate and you have to careful handle the model after applying the silver. Humbrol’s finish is much more dependable in this respect.
Strangely, I was not successful in using Alclad silver (though my friends were!). Humbrol has also a range of polishable silvers, but I have hardly used them.
I still have to improve my NMF technique, but I hope one day I can make a highly-polished Stratocruiser!
The author is a member of the Matterhorn Circle, a chapter of IPMS Switzerland
This article was originally published in IPMS Stockholms Magazine in December 2005