To begin, place an enamel, glass or plastic bowl on a flat, steady working surface, and pour in the cup of cool water. Add in the lye, and mix it all together using a wooden or plastic spoon. Keep in mind that lye is a caustic substance that is extremely dangerous and needs to be handled with care. Make sure you wear rubber gloves while working with the substance, and do not allow it to come into contact with your bare skin or your eyes.
Once the lye mixture has been prepared, proceed to pour in the coconut oil (make sure it is at room temperature, and in liquid form). Stir it in with a spoon, but do not allow the mixture to thicken just as yet.
After the coconut oil has been incorporated into the mix, immediately stir in the mink oil. Continue stirring until the mixture begins to thicken in consistency. Once it reaches the appropriate texture, pour this mixture into moulds.
Allow the moulds to sit, until the soap in them hardens completely, after which you may remove the soap from the moulds. It should slip out easily enough, but if it doesn’t, you can place the moulds in the freezer for two or more hours – the soap will contract, and you can pick it out of the moulds with ease. However, make sure you wear rubber gloves when taking the soap out of the moulds.
Finally, place the mink oil soap in a warm and dry place, lining them all up in stacks. Allow the soap to stay here for around 3 weeks, until it has aged and hardened sufficiently. Once this time period has elapsed, your mink oil soap is ready for use.