Ivo:
I did preshade the top wing, but it is very subtle, visible only upon close visual inspection. I did it by airbrushing black along the ribs. I then airbrushed the primary color, actually avery dark gray, over top.
For the bottom of the wings, i masked the ribs over the CDL and used Bud's powdered chalk technique, sealed with Future.
I'm not sure that the preshading makes much difference with black, but it would with a PC-10 scheme.
Regards,
Bob