Why Line a roasting pan with a damp kitchen towel when water bath?

Lining a roasting pan with a damp kitchen towel when using a water bath helps to create a more stable and gentle cooking environment for dishes like custards or cheesecakes. The towel prevents the cooking vessel from directly contacting the hot metal of the pan, reducing the risk of overheating and preventing the edges from cooking faster than the center. Additionally, the dampness of the towel helps to maintain moisture in the oven, contributing to a better texture in the final dish.