While watching a very interesting BBC program about Greek myths (specifically Jason and the Argonauts), I learned that human urine was used in antiquity (and modern times as well!) in the dying industry.
Urine removes oils and dirt: it prepares wool for dying and leaves it extra soft to the touch. Also, urine is an extracting agent that will give you an incredible pigmentation; and, it serves as a fixative.
Some said that fresh urine is the best; although, you will need a huge amount to dye fabric for any given garment :0!