Melt hard oils and butters until fluid. Combine the glycerin and the water, then carefully sprinkle the mixed lye over the surface.
Mix well to ensure that the lye dissolves completely. Add the oils to lye-water.
Cream soaps like to be processed warmer (60°C +) than CP soaps. It is not unusual to see a curdled mass at this point. This is due to the stearic acid becoming neutralized by the lye.
Using a stick blender, blend for 1-2 minutes at a time, allowing the blender to rest for 2-3 minutes before whipping again.
The mix may take 5-10 minutes to become homogenous. About halfway through the mixing, add your essential oils mix, if using.
There is a danger of separation if you do not mix long enough. You will eventually develop an instinctual feel for “trace” with these materials.
In the meantime, the best way to describe trace in a whipped cream soap in that it is much thicker than regular cold process soap when it traces. You will also note a shift in creaminess when the soap is at trace.
When your soap has traced, pour into waiting sterile wide-mouth jars or tubes. Allow to stand for approximately 7-10 days before using.
Test pH. It should be around pH 8-9 range.