Color Question

[klemchen]

Hello everybody,

on the palette of the RLM there were two shades of yellow: RLM 04 was a saturated yellow, often shown with a very slight touch of orange. It was used as code color for fuel and a number of other markings. RLM 27 was a brighter kind of lemon yellow. Its purpose is stated in the literature as marking color, but I have never found the slightest hint as to what was to be marked by it. To me the number in the RLM color list seemed to suggest that originally it was intended as the color for third Staffeln in the Gruppe, but as far as I know, 04 was nomally used for that purpose.
Now on a number of occasions I have seen photos of some Fw 190 A-4s of JG 54 with non-standard paints, whose cowling undersides appear to be orange and the other yellow markings in a rather saturated hue. Since color photos cannot be taken as precise samples, I think the components of red are grossly exaggerated on those photos, so the cowling undersides were 04 and the other yellow markings were 27.
Could it be that 04 and 27 were just interchangeable? But then, why two different yellows? Because of being composed of different chemical materials?
Since this question has been bothering me for a long time, I would be too glad to get an answer.

Regards,
klemchen