Naturally water proofed wool comes from the way it is processed after the sheep is shorn. Some sheep breeds are very greasy and when the fleece is washed not all of the lanolin is scoured out. These sheep usually wear jackets to keep other vegetable matter out so vigorous scouring is not needed. The fleece is well skirted also. Some breeds of sheep's wool, like the finer fibered ones, felt very easily and this also helps keep the wool waterproof. Vigorous washing of a piece of wool cloth in alternating hot and cold water, and then a dryer will also cause felting which will help to waterproof. Go easy....you don't want to over felt.