Suede is created from a split piece of animal hide, making it less-durable than traditional leather. The underside is then sanded to create the soft finish. Because suede is so delicate, it's prone to water marks and stains, especially the stains created when your suede-collared wool coat rubs against your neck and face. Over time, the oils from your skin will leave unsightly discolorations on the suede collar. It's integral to clean the discoloration and restore the suede's appearance without harming the delicate fabric.
Lay the coat on a towel with the collar flattened and the discoloration or stains clearly visible and accessible. Cover the stains with a thick layer of cornstarch or baking soda. Allow the coat to sit at least eight hours, or overnight. The baking soda or cornstarch will soak up the body oils or water from the suede, helping to eliminate the discoloration.
Shake off the suede collar to remove the cornstarch or baking soda. If any remains, brush it off with a suede brush, which is available at leather retailers. If the stain persists, reapply a layer of cornstarch or baking soda and allowing the coat to sit overnight.
Examine the stain. If it persists, dampen the corner of a washcloth with white vinegar. Gently dab at the stain until it's eliminated. Dampen a separate washcloth with plain water and dab at the affected area to remove the white vinegar.
Dab away the excess liquid from the suede with a paper towel or washcloth. Allow the suede to dry completely. Restore the suede's nap by rubbing an old toothbrush over the area gently, using short, back-and-forth motions.