Mix the cool water with the lye in an enameled, plastic or glass bowl.
Add the lye mixture to the coconut oil in a plastic, glass or enamel bowl. Stir it well with a wooden or plastic spoon, but don't yet allow it to thicken.
Add the mink oil and continue stirring until the mixture thickens.
Pour the thickened mixture into molds.
Wearing rubber gloves, remove the soap from the molds. If the soap is difficult to remove, put the soap in the freezer for two or three hours. The soap will contract and come out of the molds easily.
Stack the mink oil soap in a warm place and allow it to age and harden, at least three weeks.