The winter whitewash is added. Before the whitewash, I sprayed Testors Dullcote on the tanks. I highly recommend Testors Dullcote because it's easy to apply, didn't mess with the decals and dried quickly.
I did a lot of research on whitewashing effects and settled on using watered down VMC white in various coats.
Little did I count on my daughter, the aspiring artist, to break out her artists palette, mixing tools and her animal hair paint brushes and demand to do the wash herself after seeing my test piece (an old Pz IV F-2).
I handed her turrets and hulls in assembly line fashion while she mixed the white to a consistency and transparency she liked. She used q-tips to soak up any access white if it pooled too much.
She doesn't play FOW, but she knows how to do a fine job adding washes!