Having hopefully digested the preamble let's begin in reverse order with the Shiden-kai. In the late and lamented Asahi Journal, Vol.3 No.1 (undated), Robert C Mikesh produced a report on the measured paint colours of several extant airframes in the NASM collection. This report included the surviving Shiden-kai s/n 5341 and the traces of original paint examined were found when the Champlin Fighter Museum undertook the aircraft's restoration.
Unfortunately the Shiden-kai paint colour identified as being Thorpe's N1, Munsell 10 GY 2/2 was not reported to be measured so it must be presumed to be a visual matching only. Despite this it is worth putting the identification within the context of the exercise which led to the report by directly quoting Mr Mikesh's approach.
"What I did at this point was to select the Navy green and gray color chips that I felt were as close to measured readings as possible. Some had to be 'bracketed' by selecting two, three or four chips that surrounded the colorimeter reading obtained. Amazingly, about 70% of the selected chips separated themselves in either the Black Green (N1) or the Dark Green (N2) groupings without question. Included as reference were the two color samples of Munsell values that have been accepted for many years as Black Green and Dark Green. Although neither of these two chip color values came out as an actual color reading from any of NASM's aircraft, color samples within these two respective groups had negligible differences. This further validates Don Thorpe's Munsell color value for N1 and N2 as being 10 GY 2/2 and 10 G 3/2 respectively. These two values that I identify as a Thorpe Number in the following data were derived by this grouping of greens just described."
And he presented a timely warning about the danger of literal acceptance of FS595B equivalents:-
"A few Federal Standard equivalents are mentioned - but as in the past, I can find few Japanese colors thought to be true colors that can be matched to the FS system."
In their book 'Genda's Blade', an account of the 343rd Kokutai, authors Henry Sakaida and Koji Takaki address the subject of the colours of the Shiden-kai within a dedicated chapter. They describe a "glossy dark green/olive finish" in the colour range of FS values 34052, 34077 and 34079 but also refer to the NASM example as being painted in "a semi-gloss black green(Munsell 10 GY 2/2)".
This immediately throws up an anomaly, because two of these FS values are closer in value to Munsell 10 G 3/2 (N2) than to 10 GY 2/2 (N1). The calculations are as follows:-
34052 = 10 GY 2/2 @ 9.51 & 10 G 3/2 @ 8.37
34077 = 10 GY 2/2 @ 3.53 & 10 G 3/2 @ 6.52
34079 = 10 GY 2/2 @ 12.4 & 10 G 3/2 @ 9.81
However, none of these FS comparisons could be described as close matches or even reasonable matches, which brings us back to Mr Mikesh's qualifying comment about the unsuitability of FS 595B when attempting to determine the original colours. But regardless of this the residual problem is that the range of colour suggested by the FS values is as much like N2 as N1, if not actually more so. This brought a feeling of déja vu from the subject of Irving colours explored here.
Peter Fearis also examined a surviving Shiden-kai for the purposes of his excellent monograph on the type, this being s/n 5312 at the USAF Museum, Dayton, Ohio. Although again visually matching, he describes the original paint surface colour as being a "dark green" close to FS 34092 but qualifies this by commenting that "for authenticity a small percentage (5%) of Royal blue should be added to this green, the change of hue is very subtle." FS 34092, even without a little blue, is a long way from Munsell 10 GY 2/2 (N1) @ 11.9 but closer to Munsell 10 G 3/2 (N2) @ 4.64. As one of the lurkers might say - hmmm.
Aero Detail 26 on the Shiden-kai describes the paint colour as "Kawanishi Dark Green-Black". There are no values given for it but the dark green used in the printed schematics appears to be more like N2 than N1.
Model Art #272 on IJN Fighter Camouflage & Markings has a painted chip identified as "Kawanishi Deep Dark Green" which also provides Gunze (GSI Creos) and Tamiya paint mixes for it as follows:-
Gunze: H4 5% + H5 45% + H6 50%
Tamiya: X5 62% + X3 30% + X9 3% + X1 5%
The paint chip in this book is closer to Munsell 7.5 GY 3/2 with no close FS equivalent. It is almost exactly similar in value to RAL 6020 Chromoxidgrün (Chrome Oxide green) but it is not like 10 GY 2/2 N1. It may be of interest to know that this RAL colour is available as a semi-gloss paint (32)363 'Dunkelgrün' in the Revell range (and a lovely colour it is too). In the text about the aircraft in this reference the colour scheme is just described as "the standard dark green".
Model Art #304 on the N1K1/N1K2-J also includes a painted chip of dark green described as 'An Ryokushoku' (Dark Green Colour) that is between 10 G 2/2 and 10 G 2/4 in appearance, not quite as dark as the former but with a strong and rich viridian green chroma. The paint mix for this chip is suggested from the "Mr Color" range:-
#6 50% + #5 40% + #4 10%
The IJN HQ Proposal for Revisions to Aircraft Planning Procedures (Hikoki Keikaku Yoryosho Kaitei-an) of March 1944 included a table of standard colours and codes from Kariki 117 and specified the upper surface paint colour to be D1 'an ryokoshoku' (dark green) - see previous article - with the lower surfaces as J3 'hairykushoku' (ash green - described this way in the 1944 report even though the original Kariki 117 described J3 only as ash colour ('hai iro').
Another dichotomy is in the way the original Kariki 117 'D1' swatch has been interpreted by two different researchers, shown above as D1 'A' and D1 'B' together with a facsimile of the actual swatch in comparison to a page of the JPMA deck (note that there is a strong and misleading blue-green caste to the reproduction of this image). If accurate there is very little green chroma in this colour - which may be the result of degradation. Attempting to reconcile the paint colours found on the surviving Shiden-kai with the Kariki 117 swatches illustrates perfectly the difficulty of comparing paint colour standards to applied paint - even before considering the effects of age, heat and UV degradation. Any attempt to be unequivocal or dogmatic about this subject and the associated issues would seem rash.
Returning to Don Thorpe, he lists the "George" as predominantly having N1 uppersurfaces but records N2 and even the dark grey-green N3 (see Thorpe Colour Table) as variants. All five N1K2-J profiles in his book 'Japanese Naval Air Force Camouflage and Markings World War II' are captioned as having N1 upper surfaces although the colour chosen appears more like N2!
The aspect of the various comparisons explored here that is most concerning is the citing of various green values that are across olive, viridian and grey/blue-green colour families as well as encompassing both the N1 and N2 Thorpe identified colours. Even allowing for variations it makes it difficult to pin down a colour that may be said to be "typically" characteristic of the Shiden-kai paint. But looking at the vast array of paintings, profiles and models of Japanese Navy aircraft it is apparent that the problem is widely experienced.
So, Shiden-kai N1 or N2 or both? The next instalment will explore the way the Japanese Navy greens evolved in the February 1945 Joint Army-Navy Standard document 8609, consider the available hobby paints, ponder kit instructions and look at other colour details for Shiden-kai. Does it get any easier? Believe me, no.
Image credits: Photo©2010 kitty kitty; Rendered colour chips ©2010 Straggler; facsimile Kariki 117 swatch Summer via Fuku