color profile WW 1 aeroplanes

Why were the bottoms of the wings painted yellow?
To blend in with the sun please help me with this queston.
I am building basla wood models . I want to be accurate.
Thinks for you help.

[PeterL]

It's not painted that colour Larry, it just is that colour. Depending on the flax used to make it unbleached linnen (unbleached because bleaching weakens the fibres)ranges from off-white to a darkish biege in colour. This natuaral colour would be affected by the application of an oil based varnish as a protection after doping and that's what gives it the yellowish appearance.

Regards

Peter L

Its because the common thing to do was to use clear dope to cover the linen, thus the yellow appearance (actually tan)