Here’s a short description of a Milk Bath. Here’s a recipe for a milk bath:
Making your own milk bath is simple and quick. Add 2–4 cups of milk or buttermilk to a warm bath, soak for 20 minutes or so, and scrub the loosened skin cells away from your body with a washcloth or loofah in soft, circular motions. You will need to be extra gentle with delicate areas of your skin such as your neck and thigh to avoid abrasion burns.
When you are finished, rinse the milk from your body thoroughly with a quick shower and wipe the oils from the tub while they are easy to remove.
After your beauty bath, you may notice your skin is slightly oily. That is normal. It’s simply the natural moisturizing effect of the milk. Exfoliating your skin too often can dry it out and the natural oils in milk will help keep your skin moisturized, making your milk bath the perfect beauty treatment for creating supple baby-soft skin.
It appears that there may be some science behind this idea. Lactic acid is a mild exfoliant. It seems to be helpful for many people, but it also has drawbacks, especially if you are allergic to milk. See here for more information.