"A little learning is a dangerous thing" said Alexander Pope. Well in modelling terms it is probably not dangerous - perhaps just misleading and rather irritating. Perhaps for modelling purposes Amos Bronson Alcott is more succinct: "To be ignorant of one's ignorance is the malady of the ignorant". Mr Alcott's observation is vindicated online on an almost daily basis and it often seems that those most afflicted with the malady are the most persistent imparters of opinion and information.
One of the most prevalent outcomes of "a little learning" is the dissemination of information in diluted or misunderstand forms which then become modelling conventions. There really does need to be a distinction drawn between the freedom to paint one's model whatever one likes and the sometimes unstated implication that the choice represents an outcome of research intended to impart "a little learning" to others. By such dubious means we have a generalised belief (reinforced by hobby paint companies) of aotake as a metallic blue-green paint applied in all Japanese aircraft cockpits and Luftwaffe sandgelb used by Kawasaki to paint the interiors of all their aircraft.
In Army form 'aotake' was introduced as a translucent dark blue primer for the interior of aircraft by the Army aircraft painting regulations of 3rd March 1932 (that is the Army painting regulations - once more - the Army painting regulations). It was not metallic per se but the application of the clear blue to bare metal surfaces no doubt gave (and gives) that impression. On 5th February 1936 the regulations were revised and the use of aotake (青竹色 - literally blue green bamboo colour - or sometimes written as 淡青色透明 - literally thin, translucent, light blue colour) was replaced by a dark greyish blue opaque primer paint which became colour standard #3 Hairanshoku or Hai-Ai-iro (灰藍色 literally ash indigo colour e.g. a greyish blue) in the Army colour standards. In practice this new paint was usually applied to internal crew areas whilst 'aotake' continued to be applied to other internal areas. Was #13 Ao iro ( 青色 - blue colour) also applied to some cockpits, either in error or expediency? Maybe.
There are two clues to the appearance of this colour standard. Firstly the actual Hess-Ives values used to measure the authorised range of hue in the procurement of Army paint supplies and secondly a pre-war French colour card which illustrates the colour and explains its use. Was there a connection between the French bleu nuit (night blue) interior colour and the Japanese interior colour? Perhaps. There is also another thing to bear in mind which is the distinction to be drawn between the colour standard and the actual paint supplied and applied. The two are not invariably the same. The promulgated colour standard displayed a variable and authorised range against which the paint suppliers (or more usually aircraft manufacturers) attempted to match. This distinction does seem to be misunderstood or perhaps under-appreciated.
In Methuen terms the median standard colour is a dark greyish blue between 23 E-F 5. The closest standard Munsell notations are between 2.5 PB 3/2 @ 2.98 and 2.5 PB 3/4 @ 2.40. The closest FS 595b value is 25053 @ 3.61 (but too blue), but 26118/36118 @ 7.02 (too grey) is often cited and indeed may provide a better scale impression although it is not quite blue enough. (A comparison value of 2.0 or less equals a close match). Ken Glass kindly advises that a reasonable out of the bottle match is Pollyscale RLM 24 Blau but it may need to be lightened with white and/or toned down with grey to match the swatches.
The survival of badly weathered remnants of this paint in cockpits can give rise to a misidentification as aotake, but in practice diluted #3 spray or brush applied is not dissimilar in appearance. Aircraft interiors known to have been painted to #3 standard are Type 91, Ki-27, Ki-21, Ki-36, Ki-43, Ki-44 and Ki-48. Ichiro Hasegawa described the interior of a Ki-55 ('Ida') as having been painted in two colours, one being the bluish grey and the other a yellowish grey-green (the latter colur will be examined in Part 2). He also described the interior of both the Ki-21 ('Sally') and Ki-27 ('Nate') as being painted in this bluish grey which created a "gloomy impression", even the gunners mats being painted the same colour.The use of this colour continued until the introduction of new requirements on 15th June 1943 - of which more anon.
One of the aspects of the study of Japanese aircraft that continues to surprise me is the inability or perhaps unwillingness of some to reconcile the known (and published) Army colour standards with the extant appearance of paint on artifacts. It sometimes seems as though an element of being in denial exists, as though somehow the Army colour standards are not real and an opinion about a 65 year old fragment of paint without antecedence or provenance is more reliable. Hopefully one day we shall be able to move on from a quasi-religious veneration of the paint fragments to a broader and more equivocal appreciation of all the evidence.
Once this mini-series on interior colours is complete I intend to make it available as a pdf with appropriate hobby paint mixes which we are working on.
Image credits:- Ki-21 crew © 1942 Front Magazine; Colour chips © 2009 Straggler