Usage: Run a bit of the stone under a tap and rub onto any area where you want to prevent body odour - yes, it will work on armpits and feet!Regular commercial deodorants and antiperspirants contain harmful chemicals! Avoid these nasties with deodorant stones!How does the stone work? The stone targets the bacteria on the skin surface, which is what causes smells. Using the stone will not clog your pores or leave any residue or by-product. It will not stain clothing. The stone deodorises by acting on the bacteria. It is not an antiperspirant! Sweating is natural and important! What is the stone made of? The stones are made using natural mineral salts, and the main ingredient is potassium alum. Potassium alum it is not an antiperspirant and products containing it do not reduce sweat production.It is not the same as Aluminium Chloride and Aluminium Chlorohydrate, which are commonly found in conventional antiperspirants and which people want to avoid! (Read more below)How long will one block last? It can last for a year or more, depending on usage!What is the difference between potassium alum and Aluminium Chloride and Aluminium Chlorohydrate?Aluminium Chloride and Aluminium Chlorohydrate react with peptides and amino acids in the skin to form a gel which then blocks sweat ducts and glands, preventing perspiration. This is why they are used as antiperspirants in conventional deodorants. They have a small molecular mass (usually 250-350 Daltons) which means that they can readily penetrate the skin, entering the body.Potassium alum has a much larger molecule (approx 480 Daltons) which is too large to be absorbed through the skin. Instead of forming a gel which prevents perspiration, potassium alum sits on the surface of the skin. It is anti-bacterial and does not allow the bacteria responsible for causing bad odours to multiply.