Prepare your mold. Wood molds will need to be lined with freezer paper or wax paper. Silicone molds are ready to use as is. You can also use any box if you line it with freezer paper, wax paper, or a thick garbage bag.
Put on protective gear, place a glass jar on the scale, and tare the scale.
Pour distilled water into the jar until it reads 12.54 oz.
Put a second jar on the scale and tare the scale.
Carefully pour lye into the second jar until the scale reads 5.09 oz.
In a well-ventilated area or outside, slowly pour the lye into the water.
Stir the mixture until the lye is dissolved. It will become quite hot so be careful if you need to move it.
Let this mixture sit and cool to between 100-120°F.
While the lye is cooling, measure all other ingredients EXCEPT the essential oils and warm them together in a pot or slow-cooker.
Once they are melted, remove them from the heat and let cool to between 100-120 degrees. I use the infrared thermometer about every 5-10 minutes to test the temperature. This works really well, but a candy thermometer placed in each container also works. If one is cooling faster than the other you can put your oils back on the heat source or the lye/water mixture in a warm water bath to slow the cooling process a bit. Ideally, you want the lye/water and the oils to both be between 100-120 degrees and within 10 degrees of each other.
When the temps match, slowly pour the lye/water into the oils.
BEFORE you turn your stick blender on, make sure the blade is completely under the mixture or you will splash it everywhere. Use the stick blender to bring the batter to a light trace. It should be slightly thick and resemble cake batter.
If using, add the essential oils now.
Blend essential oils in by pulsing the immersion blender a few times. This should bring the mixture to a medium trace. You can tell when you have reached a medium trace by lifting your blender up out of the mixture (in the OFF position) and observing how the drips behave. They should leave a trail or “trace” on the surface. If you don’t use essential oils, just pulse your blender a few more times to bring it to medium trace.
Pour the soap batter into your prepared mold, using a spatula to get it all out. Remember that the soap is not fully “cooked” yet at this point and could still irritate your skin so you should still be wearing your gear.
Put the mold somewhere it can sit for 24 hours.
Place an upside down cardboard box over the soap and cover with a towel. If your house is warm the towel may not be necessary.
Let sit for 24 hours.
You can now remove your soap and cut it. This recipe in the silicone loaf mold makes about 12 bars weighing approximately 4.5 oz each, but you can cut them whatever size you like.
Stand the bars up in a dry area with an inch or so of space in between to allow for air circulation and let them sit for 4-6 weeks. This will allow the soap to complete the saponification process. The soap will also lose some of its water during this time making the bar harder. The harder the bar, the longer it will last.
Soap Making Clean-up: Rinse the jars and any supplies that had lye or soap batter in them well, with running water. I have washed the tools two different ways. You can pour some vinegar in a sink filled with hot soapy water and wash them in there, or you can wash your well rinsed dishes in the dishwasher.