Step 1

Make the lye water. Measure the lye and water in separate containers, using a digital scale.  Combine the lye and water by adding the lye to the water, then stir until dissolved.  The lye solution will shoot up in temperature and become hot.  Set aside to cool in a safe place.

Step 2

Melt the oils. Measure the castor oil and coconut oil using a digital scale.  Melt over low heat in a stainless steel pot until fully melted and 140 degrees.  Set aside to cool in a safe place.

Step 3

Blend the components. When the lye water and melted oils have cooled to about 110 degrees, combine them by pouring the lye water into the melted oils.  Blend with a stick blender until a thin trace is reached.  (The mixture will thicken slightly and no droplets of oil are visible.)  Add the fragrance, if using, and stir in by hand.

Step 4

Pour into mold. Immediately pour into a soap mold with individual bars.  (The soap dries too hard to cut easily if made as a loaf.). Remove from the molds after 24 hours and allow to cure 2 weeks more before using.  Store the bar in a place that will allow it to dry as much as possible between uses.