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sky type S origin

Discussion in 'General Aircraft Chat' started by selrach, Nov 4, 2009.

  1. selrach Scale Model Member

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    Hallo! Can anyone tell me when and under what circumstances the British light green underside color "sky type S" originated? What were the reasons that light green would be preferred to a light blue color? What does the designation type S mean? Thanks!
  2. stona Scale Model Member

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    Cripes you may have opened a bit of a can of worms here! Firstly "TypeS",this refers to the very finely ground pigments in these paints which gave a smooth finish. "S" for smooth, no controversy there!
    The origins of the Sky colour lie in research done at Hendon, I think in 1939, by No1 PDU using Blenheims and Hudsons. Other blue/ green colours at the time included Eau de Nil, at least two versions of Sky blue and duck egg green. Presumably these were the basis for the tests. These colours are the subject of endless debate and I don't have a clue what some of them actually looked like!
    The new formulation "Sky type S" is arguably closest to the older BS 381 (1930) No16 duck egg green,though lighter and less intense and the Royal aircraft establishment decided that this gave the best camouflage.Its origins may lie in a paint made by Titanine Ltd called camotint.
    Paul Lucas (from one of whose books I culled most of this) quotes Air Ministry signal X915, 6th June 1940, as cancelling all previous instructions on the painting and marking of the undersides of fighters and stating that the undersides of all fighter aircraft were now to be doped to Sky Type S and underwing roundels removed.
    The formualtion was apparently something of a challenge to get right and it took some time after the acceptance before suitable quantities appeared.
    The older colours were allowed/used as substitutes until existing supplies were depleted.
    This explains the never ending debate about exactly which colour was on the underside of what aircraft during the transitional period,of course we'll never know for sure.
    Luckily for we model builders different manufacturers versions of "sky" differ enough to give a nice variety of shades on the shelf so I don't beat myself up about it!
    Cheers
    Steve
    BTW the other camouflage colours were also type S paints yet noone ever says "dark earth type S". Strange.
    Last edited: Nov 5, 2009
  3. stona Scale Model Member

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    Regarding the relationship between Camotint and Sky, I found this quote on my computer. Sadly I don't know where I got it from and so can't give credit where it is due for which I apologise.

    "The standard colour was created and formulated many months prior to the BoB, based on that for 'Camotint' (a commercial name) and first described as "Light Sea Green" in operational units before the terms "Duck Egg Blue" and "Sky" were used. As Andrew has already noted its application to fighter aircraft was dependent upon the availability of the actual paint. The "confusion" about Sky in the June-August 1940 period was in the commands and units to which the orders were issued and the reported scarcity of stores paint which supposedly resulted in unit mixing and/or the use of other standard colours instead in order to meet requirements.

    Whilst the MAP Standard swatch may have been "fixed" the pigment formula was always imprecise and one way to a better understanding of the possible variations in the colour is to use this to do your own mixing exercise. It was white with about 4% yellow oxide (yellow ochre) and a trace of Prussian Blue. Mixing to match the swatch is quite difficult and it is easy to shift the colour towards more blueish or more greenish. The type of white used also has a strong influence on the resulting appearance. In addition the pigment yellow oxide is highly dependent upon source, process and purity. To a certain extent the permutations are reflected in the variety of supposedly 'Sky' hobby paints available, few of which are identical to each other."

    Hope this helps. The last sentence certainly rings a few bells.
    Steve
  4. selrach Scale Model Member

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    Thanks for the responses

    Thanks for your help. One thing that puzzles me is why a light green shade was used. Under what circmstances did the RAF researches think that light green undersides would be best?

    1. Was it because the aircraft would be harder to see when parked on the ground? When I spoke to Jerry Crandall once about late war Luftwaffe camos, he thought the Germans used the light green-blue shades for this reason. He is not sure though.

    2. The sky near the horizon sometimes has a greenish or duck egg hue. Does light green blend in better when doing low level fighter sweeps for instance?

    I suspect the RAF was very systematic about why they did what they did. I read once they reduced the white and yellow portions of the fuselage roudels which significantly increased air to air concealment. I just don't know the reasons why for the underside green.
    Last edited: Nov 5, 2009
  5. stona Scale Model Member

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    I suspect that the Sky colour was considered to give better concealment for the aircraft when seen from below against the sky (whether from the ground or another aircraft). I'm basing this on a communication I read and can't now find (sorry) which rejected the Sky colour in favour of the much bluer Azure in the mediterranean theatre because it was not considered suitable for the brighter skies in that theatre. I realise that is a bit of a lateral reasoning but it would seem to fit the facts.
    As far as those late Luftwaffe colours coming down the sides of the aircraft I had always assumed that that was to aid ground concealment, they also wrapped the upper colours around the leading edge of the wings and onto the lower surface. I can't see how that would aid camouflage in the air. Mind you if Jerry Crandall isn't sure I'm not going to argue with that!
    The RAF did indeed alter their roundels but then some Luftwaffe units by 1940 were over spraying the large white borders on their fuselage crosses with a dark colour (RLM 70 or 71?) to reduce them for the same reason.I remember a picture of this in one of Merrick's books I think.
    I think a lot of the confusion over Sky comes from typical British befuddlement with all the new paints and changing schemes. The colour is referred to as duck egg blue, duck egg green,sky blue and even sky grey in documents but I reckon these are mistaken references to the new colour when no storeman,or it seems people writing the orders, were exactly sure what the hell it was. Remember they'd been using the older colours since 1930. They just plumped for the nearest familiar phrase to describe a blue/green paint.
    I can hear a storeman with twenty years in saying "we've got some of that new duck egg green paint" even if the tins had "Sky" in 2" letters on the lid!
    Steve
  6. stona Scale Model Member

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    Here is an interesting quote from Edgar. The man is an authority on Spitfires and I suspect he knows a thing or two about paints!

    "The whole idea of a green, for a/c undersides, is, almost certainly, attributable to Sidney Cotton. He watched the Maharajah of Jodhpur's Lockheed 12A take off from Heston, and noted how quickly, with its pale green colour, it disappeared from view. He had his Lockheed, G-AFTL, painted a slightly lighter shade, and registered it as "Camotint."

    Sidney Cotton from wikipedia.

    "Frederick Sidney Cotton OBE (17 June 1894 – 13 February 1969) was an Australian inventor, photographer and aviation and photography pioneer, responsible for developing and promoting an early colour film process, and largely responsible for the development of photographic reconnaissance before and during the Second World War. He numbered among his close friends George Eastman, Ian Fleming and Winston Churchill."

    so he definitely knew a thing or two about colour!
    Cheers
    Steve
  7. selrach Scale Model Member

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    Dear Steve, Thanks for the info. Fascinating indeed. If you find out more details please let me know.
  8. stona Scale Model Member

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    No problem, I (and I suspect others here) like to flick through old books and references when I'm at home. It is astonishing how much you forget you have read! Of course you have put the Sky "conundrum" in the active pile.
    Cheers
    Steve
  9. stona Scale Model Member

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    Just going to ressurect this with more information from Edgar Brookes,who I mentioned earlier. He has unearthed the following document at the PRO at Kew. Paragraph 2 makes it fairly clear that the "Sky" colour was not derived from Camotint,it was infact the same colour.

    [​IMG]

    We can still argue about which colour was actually applied to frontline aircraft post June 1940,but there is no doubt what SHOULD have been applied.
    Of course once the orders for new camouflage scheme were issued "clarifications" like the one below must have considerably added to the confusion which still persists 70 years later!

    [​IMG]


    Cheers
    Steve
    Last edited: Jul 7, 2010

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