No.2 PRU Royal Blue AKA "Bosun Blue" - Middle and Far East PR colour seen on Hurricanes and Spitfires

[Troy Smith]

With the release of the Arma Hobby Hurricane Reconassiance boxing, with Mk, IIb PR/TacR options, and being discussed in the rumourmonger thread,  but a round 

 

https://armahobbynews.pl/en/blog/2024/10/03/new-1-48-reconnaissance-hurricanes

 

 

https://www.britmodeller.com/forums/index.php?/topic/235077295-hawker-hurricane-mk-iic-148-arma-hobby/page/16/

This has brought up the subject of what colour blue is the scheme above? 

 

And a reference photo

BM969 IIb M XX 20MU 26-11-41 52MU 10-12-41 shipped 12-1-42 Takoradi ferried 2-42 ME India 1-4-42 ASU Karachi 23-11-42 3PRU 681Sq 'Q' SOC 27-9-44

 

The overall colour is likely to be No.2 PRU Royal Blue,  this being a mix developed by No.2 PRU unit in Egypt.

 

From a Colour Conundrum by @Paul Lucas

Partially available here fortunately https://www.discountmags.com/magazine/scale-aircraft-modelling-july-2020-digital-m/in-this-issue/5ef9bb141b265

 

"No.2 PRU Royal Blue
The RAF Form 540, Operations Record Book for No.2 PRU based at Helipolis in Egyptopens with an entry dated 1 June 1941. The entry describes the origins of the Unit, its operational policy, its organisation and is equipment. Paragraph 5 is headed 'Camouflage' and states
'5. CAMOUFLAGE. The aircraft are painted with “Royal Blue” Dope and with a matt finish. This has proved to be invisible to the eye at 14,000'.'
Just over a month later, the entry for 3 July 1941 again made reference to the camouflage finish of No. 2 PRU's aircraft thus
'EQUIPMENT. Hurricane W.9116 was taken to ALMAZA to be re-painted with a Matt-Blue finish. No. 102 M.U. had painted it with glossy paint.'
On 25 July the ORB makes reference to the formula of the Matt Blue colour as follows
'EQUIPMENT. Hurricane V.7423 returned from ALMAZA where it had been re-camouflaged with blue matt dope. The dope is mixed as follows;- 5 galls, De Lux Bosun Blue, 16 lbs. Zinc Powder well filtered, 7 pints of turpentine, 31 lbs. Black De Lux.'
As can be seen from this, the matt blue finish used by No.2 PRU Blue was specially mixed for the purpose using a colour called 'De Lux Bosun Blue' as its basis. There has been some speculation as to whether the reference to 'De Lux' was a misinterpretation, misunderstanding or misspelling of the word 'Dulux', which was a trade name used by DuPont for their enamel paints by the Officer who compiled the ORB. This might not be so far fetched as it sounds as British Australian Lead Manufacturers PTY Ltd were associated with DuPont and marketed Dulux finishes whilst a link with Middle East Command is provided by part of a letter from the Royal Australian Air Force's Chief of the Air Staff to his RAF counterpart dated 16 July 1941. This stated
'As you may know, two Officers from the Middle East were here in April to place orders for a large variety of general equipment wherever there was a likelyhood of early supply.'
There followed a list of the types of materials ordered which included 'Paints and Dopes.' Thus it is possible that a Dulux colour called 'Bosun Blue' may have been obtained from Australia for some other purpose only to be pressed into use as an ingredient in the mixed No. 2 PRU matt blue.
There is no known sample of this colour, so it is impossible to say with any degree of certainty what it might have looked like. The photographic record does however appear to indicate that it was a dark blue, slightly lighter than that used in the British national markings which had a theoretical specular reflectivity of 4%. The late Geoff Thomas, who as far as this author is aware was the first researcher to come across this colour, stated that it was an ICI finish and likened it to BS 381C No. 105 Oxford Blue and FS 25051, and as having a specular reflectivity of 6 %, though on what evidence this was based is unknown.
Since this colour was first made known to modellers, there has been a tendency to simply refer to it as 'Bosun Blue' which is incorrect as this was only one of the ingredients. It is therefore proposed that a more accurate name for this colour might be 'No.2 PRU Royal Blue', which takes into account its origin, purpose and hue."

 

Geoff Thomas mentioned above was stationed in SEAC, and wrote several books.

The one relevant to the discussion here is Eyes For The Phoenix: Allied Aerial Photo-Reconnaissance Operations South-East Asia 1941-1945

 

which despite seeming very niche, has the best run down of colour schemes used in SEAC, as well as some very detailed colour information quoting Munsell, Methuen as well as approx matches in FS595 (post war US government standard paints) 

The book is OOP,  is highly recommended and pdf's can be found online if you would like to read more, it one that does work much better as a book though, and it can be found at a reasonable price used if you look around.

 

Geoff Thomas likened it to BS 381C No. 105 Oxford Blue and FS 25051

 

also on page 177 are these matches

 

Methuen 21E8

approx Munsell 7.5PB 2.5/8

reflectance 6%

 

Note  BS 381C No. 105 Oxford Blue is very similar to MAP Blue, the very dark blue used in wartime markings.

 

This is a daylight photo of MAP Blue from the RAF Museum MAP chips, with the FS595 25051 overlaid

 

Note 25051 is 'redder'  the MAP Blue

 

previous discussion on this have suggested No.2 PRU Royal Blue to be a very dark reddish hued blue.

 

As best can be made out, 2 PRU used a lighter colour for their roundel blue, 

Spitfire BP911 2 PRU Middle East 1943

 

note Gladiator in background,  with dark blue in the markings,  and not a film or filter effect, as the red looks dark and the yellow light on the Gladiator

 

pic courtesy of @Brian Spurr  taken by his father who was in 2 PRU

 

Some Hurricanes were transferred to SEAC, or painted in the same colour, as they the two photos here show no middle east history

SEAC used yellow outlines to make the roundels stand out, the blue remaining standard MAP Blue

BH125 IIb M XX 20MU 15-12-41 Crosby 9-1-42 1PATP Liverpool 'City of Perth' 2-3-42 India ARC Karachi 3-9-42 3PRU FARSU repair Chittagong 25-3-43 681Sq 'U' 26-3-43 u/c failed to lock down Chittagong CB 20-8-43 W/O EE Carpenter (RNZAF) inj SOC 14-10-44

 

Another shot of BM959

 

 

 

this is from another thread, which I need to refind the page

"I have to say the colour values for Bosun Blue which are linked to in the thread Troy in turn linked to above raised an eyebrow. They are rather "theoretical" in have a brilliance to the blue whilst being almost black in light reflectance value. Whilst theoretically possible in colourspace getting real pigments to give a paint so vibrantly saturated whilst being so dark as to appear almost black might be questionable. If they are accurate though, then it looks like Bosun Blue could be made from Ultramarine and Black - the blue they result in has a strong reddish bias."

 

" Bosun, is of course, an RN term for Boatswain - and probably in other Navies as well.  Looked up the colour as follows:-

Hex colour code - 212d4e

Comprises - 12.94% red, 17.65% green and 30.59% blue""

 

"Those colour values sound more credible. I don't speak hex codes but the code converts to the more tangible CIELAB coordinate system of L=19.014 a=6.041 b-21.918

 

CIELAB is a 3-axis Cartesian coordinate system. It's easiest to think of the L-axis as the vertical one and the a-b axis plane as horizontal.

L=0 is theoretical black whilst L=100 is theoretical total reflectivity. The a-axis and b-axis are theoretically limitless but practically bound by visible light, and the practical bounds are different in each direction. The a-axis runs from negative being green to positive being red, with the b-axis running from negative being blue and positive being yellow.

L=19 a=6 b=-22 is a very dark, reddish but fairly vibrant blue

That sounds like a substantially Ultramarine based paint to me"

 

Finally, John McIllmurray of @Aims  did a Hurricane PR/TacR sheet, in 3 scales with resin parts

https://www.hannants.co.uk/product/AIMS32P043

https://www.hannants.co.uk/product/AIMS48P040

https://www.hannants.co.uk/product/AIMS72P011

 

a couple of which are in this new Arma Hobby boxing...  BM959 and HV538, the other being  Polish operated,  

 

John did a stunning build of the 1/32nd Revell Hurricane IIB using his own sheet.

A stunning WIP here, well worth a read

https://www.britmodeller.com/forums/index.php?/topic/235129863-aims-132-prtac-r-conversion-for-revell-hawker-hurricane-mk-ii/

 

RFI here

https://www.britmodeller.com/forums/index.php?/topic/235130942-aims-132-prtac-r-hawker-hurricane-conversion-of-revell-mk-iib-kit/

 

this is a natural light photo of this mix he used, Xtracolor Gloss Sea Blue with some added crimson,  making a very dark reddish blue.

"taken outside - better resolution but the dark blue still looks almost black just like in the WWII photos"

 

 

compare with this, note the contrast with the serial as well

 

  

  @Casey  who likes analysing paint and suggesting matches and mixes had this to say on the colours mentioned above

 

=========================================================================

 

Those are three wildly different colors...

 

Here are matches:

Target: BS381c - 108 Aircraft blue, RGB: #3C4978 (L*=33.03, a=4.64, b=-27.09)
    Matches in: Humbrol (compared with 170 samples)
        DE00: 2.72 - #3F4F77 - DB0025 | No 25 | Blue - Matt | GU 5.1 (L*=34.95, a=1.18, b=-23.23)
      
    Matches in: Revell (compared with 86 samples)
        DE00: 2.34 - #39417B - 36151 | Ultramarine | RAL 5002 | GU 85.4 (L*=31.02, a=8.29, b=-31.92)
      
    Matches in: Tamiya (compared with 40 samples)
        DE00: 2.97 - #3D466B - XF-8 | Flat Blue | GU 3.4 (L*=31.39, a=3.14, b=-21.13)
      
Target: FS25051 - FS595a | GU 9.3, RGB: #4E5363 (L*=35.64, a=0.89, b=-9.76)
    Matches in: Humbrol (compared with 170 samples)
        DE00: 2.47 - #494E5B - AB0104 | No 104 | Oxford Blue - Matt | GU 1.4 (L*=33.59, a=-0.13, b=-8.03)
      
    Matches in: Vallejo Air (compared with 254 samples)
        DE00: 2.17 - #485062 - 71.005 | Grey Blue | Azul Gris | RAL5008 | GU 1.5 (L*=34.41, a=-0.42, b=-10.96)
      
Target: Methuen 21E8, RGB: #355E7D (L*=39.33, a=-8.73, b=-19.95)
    No matches with DE00<=3.00

 

Tamiya mixes VOLUME based

BS381c - 108 Aircraft blue
    Target: #3C4978, Mixture: #3D466B
        XF-8 Flat Blue: 1
  
    DE00: 2.97

For BS381c - use XF-8

FS25051 - FS595a | GU 9.3
    Target: #4E5363, Mixture: #4E5263
        XF-7 Flat Red: 3
        XF-8 Flat Blue: 4
        XF-25 Light Sea Grey: 3
  
    DE00: 0.33

This color is easily mixable using Tamiya

Methuen 21E8 - (approximate color)
    Target: #355E7D, Mixture: #4C5F79
        XF-8 Flat Blue: 1
        XF-15 Flat Flesh: 1
  
    DE00: 5.22

Not really achievable with Tamiya - deep saturated blues are not really possible since they do not have pure pigments.

 

Golden Fluid Acrylics mixes (this is what I use) - MASS based

BS381c - 108 Aircraft blue
    Target: #3C4978, Mixture: #3C4A75
        Teal: 5
        Anthraquinone Blue: 22
  
    DE00: 0.45
FS25051 - FS595a | GU 9.3
    Target: #4E5363, Mixture: #4E5263
        Primary Cyan: 5
        Teal: 3
        Cadmium Red Medium Hue: 5
  
    DE00: 0.25
Methuen 21E8
    Target: #355E7D, Mixture: #355E7D
        Titan Green Pale: 5
        Phthalo Green (Blue Shade): 1
        Prussian Blue Hue: 11
  
    DE00: 0.21

======================================================================

End quote.    FWIW,  something near to FS25051,  a dark reddish vibrant blue would be my pick, I have yet to try out out @Casey  suggested mix.

Note Casey has not as yet done the Tamiya X (gloss) series, and X-3 is a very dark blue, and is mentioned below. 

I recall it as lacking the redness suggested but I'd need to have a look in daylight.

 

Arma Hobby suggest these paint callouts for Bosun Blue ( marked with *Approximate colour) :

Hataka HTK-A055/C055, AK RC925, Mission Models MM-065, Ammo 227, Humbrol 104, Vallejo 71.300, Tamiya X-3.

 

 

@Wojtek Bulhak  @GrzeM  @Bigos  

 

I hope this is a useful round up of various posts on the subject,  there are more if you search but I don't recall any other useful bits of information,  but if I have missed any, please add them and link to thread.

Inevitably this is a subject that is going to have 'fuzzy' answers, and the choice is down to the modeller.

 

HTH

 

 

 

 

[Troy Smith]

See also 

https://www.britmodeller.com/forums/index.php?/topic/235118843-algy-spurr-photo-album-1-hurricane-iia-pr-dg622-a-converted-early-mki-l1658/

"Photo taken of my dad Algy Spurr (probably with his camera, he was a photographer in the air force). Hawker Hurricane - No. 2 P.R.U. (Photographic Reconnaissance Unit) - DG622 - Pilot is Warrant Officer Carpenter with the PR guys, my father Algy Spurr at right."

 

 

 

 

 

 

later getting 'Kathleen' painted under the cockpit

Note, DG622 was originally a fairly early Mk.I, and retained the early type windscreen when converted to a Mk.IIa

 

L1658, Merlin II makers number 573, W.D. number 117462, allotted 22-9-38 and delivered direct to 32Sq 28-9-36, 242Sq 24-2-40, 56Sq 23-5-40, 54MU 13-6-40, ATRG 15-6-40, 27MU 28-7-40, 5OTU 22-8-40, 13MU 8-12-40, 5MU 16-2-41, R-R 21-3-41, converted IIa DG622, 10 MU 28-6-41, 52 MU 18-7-41, Shipped Takoradi 6-8-41 on SS Ramsay, arrived Takoradi 27-9-41, flown out of Takoradi 10-41, reported on strength Middle East 14-10-41, Malta 1-2-42, Cat E 20-9-43.

 

107 MU modified 4 Hurricanes to PRU standards, then 103MU fitted extra fuel.  103MU received an order for 12 special Long Range PR Hurricanes, to carry the cameras and extra fuel but also full 8 machine gun armament and radio, but the order was reduced to 3.  No serials given.

 

@JackG  did this analysis of the roundel 

 

=================================================================================================

For determining the fuselage roundel diameter, it consists of two separate studies, whereby the photo is scaled to fit within a 35 inch circle, followed by another scaling for a 36 inch circle.  In both cases, the photo area of the roundel is purposely left slightly short in the width area, to account for perspective not showing the true width.  It does seem more likely to be a 36" roundel as the  red center sits near perfectly at it's original 12" size.

 

 

 

--------------------------------------------------------------------

 

 

 

For the colour study, the center has remained as dull red, since in b/w panchromatic film, the tone shifts automatically to be lighter than the blue ring.  Unless it is known for certain that the centers were also painted lighter, that then could change the results of what matches better, in terms of grey tones.   Have included as many of the standard paints that may have been available to paint over the blue.   Also included one extra sample as a mixture of Bosun Blue with 25% Azure.   This was arrived at by looking at the grey tones of the photo.

 

 

The software simulation reveals that as a straight forward repaint of the blue, Dk. Med. appears to be the closest match, though in terms of grey tones, it could go slightly lighter.   The mixture created with the Bosun and Azure may be much closer, but no proof this is actually what was done in the field.

 

 

 

========================================================================================

also

V7428

https://www.britmodeller.com/forums/index.php?/topic/235118868-algy-spurr-4-hurricane-mki-v7428-2-pru/

 

 

Thanks to @Brian Spurr for allowing use of his fathers photos

 

I'll add in the other SEAC images when I find them.

[Phoenix44]

Thanks for putting this together. Dulux was used as a trade name by ICI from 1931, but it was primarily an indoor wall paint. It's not clear Dulux was used for Australian manufactured paints until after the war. Dulux in the US was used on cars however.  I can't link to images at the moment for some reason (edit: can now add an image) but I have found a colour match chart for Chevrolets from the late 1930s through to the 1940s which includes a "Boatswain Blue". The colour chips also include "Apple Green"...:

 

I've also now found a chart for 1940 which confirms it was a Dupont paint (reference 93-2063) and was "Dulux".

 

https://www.autocolorlibrary.com/pages/1938-chevrolet-truck#parentHorizontalTab1

 

https://encycolorpedia.com/212d4e

Edited November 3 by Phoenix44

[Aims]

Thanks Troy

John