Washing something just means using very thinned paint, ink, or coloring on something so that capillary action pulls it in the little nooks and crannies to give the appearance of shadows and additional depth.
Read the FAQ's -
http://www.automotiveforums.com/vbul...ad.php?t=63623
and the How-To's -
http://www.automotiveforums.com/vbul...d.php?t=215864
for more ideas. Good luck,
ianc