Potassium Alum stones are used extensively for their ability to reduce redness and for soothing and toning the skin, and have become a hallmark of a professional shave as a result. After shaving, rinse the face and gently rub the stone over the skin. Leave for a few seconds before rinsing with warm water and applying an After Shave Balm. Dry the stone after use to maximise its lifespan.