להלן ציטוט מהספר POCKET AVIATION
some colors enjoy greater resistance to ultraviolet light.
Here is a brief guide:
High resistance to UV light:
White, light grey, pale green, light blue
Medium resistance to UV light:
Dark green, deep blue, yellow, violet, orange
Low resistance to UV light:
Fluorescent pink, fluorescent yellow, purple, fluorescent orange, black.
You can also be assisted in selecting a color if u see the Ultra Violet degradation, after 720 hours of
sun exposure: For Light grey the quality left is 24% , for White 16%, for Green 15%, for Sky
Blue 13%, for Medium Blue 13%, for Violet 11%, for Yellow 7%, for Purple Blue 7%, for
Orange 7%, for Purple 3%, for Pink 1%.
Hence the lighter a color is, the more resistance it is to UV light and therefore is very important
when considering appearance and longevity.
This book is from 1988. here's a link to a niviuk manual for the Koyot that sports skytex 40 and 45 from Porcher, which are very prevalent in modern wings.
look at page 16
white is actually the worst one, while the darker ones are more resilient to UV.
http://www.niviuk.com/downloads/pdf/Koyot_Tecnic_ENG.pdf (http://www.niviuk.com/downloads/pdf/Koyot_Tecnic_ENG.pdf)