Hello Kjetil,
Long time no see
I have been absent from all the aviation forums for way too long that you might not even remember me. I purchased your book when it was published & was proud and happy to remember the times when you have just starting with profiles & research while I was still very active on AAW and LEMB...
According to the M. Ullmann's research which surfaced during my absence - there is that new discovery with the document showing tests & application of RLM 83 Dark-blue in Med. Maybe some similar color was passing tests & preliminary application over in your part of the world?
AFAIK (but I am not paint or chemist expert just talking from experience with printing processes) when it comes to sensitivity and degradation due to the light exposure blue & purple pigments usually last the longest & one on the opposite side of the spectrum in color circle (complementary colors) fade first (yellow / orange) from the mixed colors. Has to be noted that pigments of various origin have various resistance to light, water & other weather elements even when mixed in the identical paint chemistry (i.e. RLM 74 with certain pigment and RLM 75 with it's own pigment might not fade in same way although both are Ikarol paint).
What if you guys have witnessed some non-standard Luftwaffe paint that didn't get the approval and RLM 83 got it? It would be so amazing to dig deeper into such things...
Who knows if some single engine aircraft of various usage were maybe painted in similar fashion and we don't know since we don't have their remains in front of us (i.e. Bf 109 Ts and similar). But that is now my imagination going too far. Forgive me.
Best,
Milos