Now the all-important question is what color to use? The undersides was as far as I can tell, and most references agree, RLM65 (Blue). But Plastyks instructions specifies RLM71, which obviously must be wrong (much to dark, and as far as I know the 70's series of paints wasn't introduced before 1938 when they developed primerless paints)
This page suggest the color was a much darker green than previously suggested, based on (Mombeek & al. 1999) (closer to RLM70)and that the seemingly light color was partly a result of early cheap photographic film used in most pictures from the period (where some colors look lighter or darker than in true greyscale), and partly the bleaching effect from the Spanish sun.
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From the page: "Scans of profiles of the same aircraft from (Top to bottom) Flying colours (1981), A mid-1990's decal sheet and Mombeek et al. (1999)."
Other sources suggest RLM01 (silver) RLM02, RLM03 (silver grey), Lufthansa Grey or RLM63 which noone seems to agree on what really looked like.
I'd love any input from the knowledgeable users of this forum!
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One additional profile from Wings Palette (which looks close to RLM02):
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