Eli5: Why do woolen sweaters shrink when put in the washing machine, but sheep coats don’t shrink when in the rain?

Question

Eli5: Why do woolen sweaters shrink when put in the washing machine, but sheep coats don’t shrink when in the rain?

In: Biology

Answer 1

Wool that is still on the sheep contains a fair bit of lanolin (5-25%), a fat-like substance that is secreted by glands in the sheep skin. It repels water quite well, so the wool on sheep doesn’t really get very wet. After the sheep is shorn, the lanolin is removed and used for things like cosmetics, shoe polish, etc.