A dip cup (10) comprises a cup (12) for receiving a teat, the cup (12) being connected or connectable to a supply of teat treating liquid including a foaming agent, foaming elements (34,36) for mixing air and the teat treating liquidto produce foam, and a regulator device (16) for setting an air-to-liquid ratio. The regulator devices (16) is selectable or adjustable based on the teat (10) treating liquid, so that a specified air-to-liquid ratio is achieved.