hi milshd90.

Most panel line washes are applied to a model after the final paint, decals, and clear coats have been applied.  The idea is to darken or lighten the panel lines in order to accentuate them.  In the case of the B-17G model, unless you have scribed the panel lines into the plastic, you've got raised panel lines.  In this case, you'd probably be better served by dry-brushing the panel lines rather than a wash.

I hope this helps.