For a final finish on the face, dilute a drop of black model paint in paint thinner--or whatever is on hand to clean the brush. The diluted paint should be a very light gray.
Use this diluted paint on a relatively dry brush (wipe most of the paint off the brush so that it doesn't drip) and darken the areas around the nose, eyes and ears.
If the horse has been turned into a stallion, darken the skin around the genitals. These are areas on a gray horse where the dark skin shows through the thin hair.
