Ye, the same as with armour except an armour wash is normally thicker. I might just give that a try on my B-17, just make sure its very thin. That is looking damn bloody good mate.
One thing i have been woundering about is how to get a good finish to light coloured areas, especially yellow. This been common on alot of German aircraft. But that wash has given the perfect look to the tail, and the red cowling as well.