Nubuck, suede and rough-out leathers no longer have their own naturally-occurring protective barrier. It's important to waterproof them regularly because these types of leather are more susceptible to damage without proper care. Danner's Nubuck and Suede Waterproofing Spray won't cause them to darken in color, and is breathable, which means it blocks water from the outside while letting moisture escape from the inside. This is nice for all boots but is especially important for Gore-Tex styles. Safe on fabrics like Cordura and Nylon. We do not recommend Danner's boot care cleaner, conditioner, or boot dressing on nubuck, suede or rough-out leathers as it will darken the color.