Kariki 117 Colour I3 and 8609 Colour 3-3 Tsuchi iro

The colour I3 from the Tsuchi iro (Earth or clay) colour set on Kariki 117 was once mooted as both the Zero colour and the colour of Pearl Harbour era B5N2 'Kates' (97 Shiki Kanjo Kogeki-ki 九七式艦上攻撃機  or 97 KanKo - 九七艦攻). The late David Aiken described the 'Kate' colour as 'Grey Poupon', alluding to the appearance of French mustard, but it was also described as 'khaki'. The degree of grey, green or yellowishness perceived in the colour has varied according to different visual comparisons but the 3-3 swatch from the February 1945 8609 colour standard has been deemed identical to the I3 which it directly succeeded. The Japanese Aeronautic Association measured L*a*b* values of the 3-3 swatch are shown below, unsurprisingly 'brown', together with visual comparisons made previously by Japanese researchers. 

The Ryôichi Watanabe comparison to FS 20318 seems anomalous and he described Kariki 117's I3 somewhat enigmatically in an article in Arawasi magazine (Issue 9, Apr-Jun 2008) as 'used as a second coat on Zero fighters and other aircraft, but there are several people who wrongly believe that I3 is ameiro (a light brown or amber colour)'. Did he mean a second coat as between the red oxide primer and 'grey' topcoat or as the topcoat itself?  The comparison to FS 34201 by Owaki-san takes us into Zero 'olive grey' territory.  

The question of natural metal finish (nmf) under surfaces on some Pearl Harbor 'Kates' has run long and in its 1/48 scale kits Hasegawa has variously depicted grey green or 'silver'. The late Jim Lansdale was of the opinion that the finish varied as the result of production chronology and that he had examined KanKo artefacts where the dark green was painted over nmf and others where it was painted over the 'olive grey' finish. He estimated that the last 200-300 KanKo produced by Nakajima up to August 1941 were probably in a factory applied overall olive grey scheme, implying that older aircraft already in service may have been camouflaged dark green on upper surfaces but retained nmf under surfaces. His extant sample of metal from the so-called 'Hospital Kate' did not have any primer and he had seen no evidence of any primer on the olive grey painted aircraft. Does that imply that they were possibly IJN Depot rather than factory painted after the olive grey paint was adopted for the Zero? In any event the olive grey appears to have been the warmer. more yellowish Nakajima colour. It was possibly patches of that paint showing through the dark green camouflage paint that gave rise to the idea of PH KanKo sporting 'brown' blotches on the green camouflage.  

Fuchida described the Kates as being camouflaged very roughly and hastily in green and brown (茶褐色 chakasshoku) with his own aircraft remaining 'bright' underneath, which is a little ambiguous but might suggest the aircraft was unpainted prior to camouflaging and that the under surface retained a natural metal finish. The problem with Japanese descriptions of 'brown' has been discussed before but chakasshoku appears to cover colours from dark reddish brown to yellowish brown or tawny.  The box art on the Nichimo Kate was based on his description but depicts a very dark brown. FWIW the paint on the 'Hospital' Kate is a slightly variegated Munsell 7.5 Y 5-6/2 which puts it into that familiar slightly lighter than FS 34201/16350 territory. Therefore the difference between I3 and the Zero-type olive grey is probably unimportant. One detail that is easily overlooked is that the amber/olive-grey paint was glossy whilst the dark green camouflage was duller or flat. 

A fabric sample from the 'Southeast Loch Kanko' had a layer of red oxide, a layer of aluminium and a top coating of olive grey. A piece of the rudder fabric had bright red over the olive grey layer. Jim Lansdale noted that according to Bob Mikesh the under surface fabric of a B5N amongst the approximate 50 manufactured by No. 11 Kokusho during 1939-40 was doped a blue-grey colour approximating Munsell 5 PB 6/1. That would be approximate to FS 36320, so possibly not the more neutral, dove grey of J3.  The pigments in 36320 as might be expected for a low saturated 'purple blue'  are rutile (non chalking) titanium dioxide (white), green shade phthalo blue, quinacridone red and blue shade carbon black. But in addition to the manufactured aircraft the No.11 Kokusho may have reconditioned or modified many B5N airframes from 1942 until March 1944 applying an unknown variety of paints. The B5N was also manufactured by Aichi from June 1942 to September 1943 with a run of approximately 200. Probably one of the most common pitfalls for modellers is to assume that extant paint examples from one aircraft represent all the others unvaryingly. Generally speaking Japanese modellers are much more relaxed and pragmatic about this.

The heading photo is from film footage of a Midway-era KanKo taking off and the lighter outer wings are intriguing. Is the lighter colour on this bird olive grey (or 'grey poupon'!) and was the darker green (?) camouflage applied on board the carrier with the wings folded?

Make of it what you will . . . 

Image credit: B5N photo web; Colour schematic © 2024 Aviation of Japan