Wahl clippers are generally designed for use on dry hair. Most professional hair clippers perform best when the hair is dry, as this allows for a cleaner, more precise cut. When hair is wet, it tends to clump together and may not provide the same level of control or effectiveness, which can result in uneven cuts or the need for additional touch-ups. However, some Wahl grooming products, such as certain trimmers or shavers, may be specifically designed for use on both wet and dry hair, allowing for greater versatility. It is always recommended to refer to the specific product manual or information available on the Wahl website to ensure the correct usage guidelines are followed. This will help achieve the best results for your grooming needs.