I was thinking the same but i am not that good at painting never mind trying to do a wash. i did try to give his ridges a wash, it did not come out too bad but i had a test part to paint first.
A wash is actually easier. I would suggest taking a head you don't plan to use for practice. Get a water base black paint and water it down until it is almost black water. You only need a little paint. Take a thick brush, dip it in the mix and then lightly drag it parallel to the hair lines and let the black settle into the grooves. For the actual figure you may want to work upside down so it doesn't drip on the rest of the figure.