Wearing protective gloves and eyewear, pour the distilled water into a glass bowl/jar for mixing.
In a well-ventilated area, slowly add the lye to the water. (They must be mixed in this order. DO NOT add water to the lye.) This causes the mixture to become very hot so keep that in mind for protecting the surface of your work area. Stir and let sit to give time for the reaction to take place and for it to cool back down. I use the candy thermometer to keep track of the temperature.
Meanwhile, measure the coconut oil, tallow or palm oil, olive oil, and castor oil using a digital scale.
Combine them in a non-reactive pot or Crock Pot and begin to slowly warm the oils.
You ideally want your oils and your water/lye mixture to be about the same temperature when you mix them (between 100 and 120 degrees). When the temperatures are close, slowly add the water/lye mixture to the warmed oils.
Use a stick blender to begin mixing until trace is achieved. You can tell when you have reached trace when your mixture is still fluid, but a drop or drizzle of the soap mixture stays on the surface for a few seconds before falling back in. [Just pull your immersion blender (in the off position) up and let some soap drizzle off.]
Add the essential oils if you are using them.
Pour the mixture into a soap mold. *Remember, saponification is not complete yet at this point so you still want to be wearing your gloves/eyewear.
Cover the soap mold with an upside down cardboard box and cover with a towel to keep it warm while it continues to saponify and leave for 24 hours. If your home is particularly warm you may not need the towel. If it gets too warm it could crack, which I don’t think would cause a problem but your soap won’t be as pretty.
While still wearing gloves, wash all utensils in hot, soapy water. You can add some vinegar to your hot, soapy water to help neutralize the lye.
After 24 hours, remove the soap from the mold and slice it. I cut mine about 1 inch thick.
Stand the bars upright and let them cure in a well-ventilated area for about 4-6 weeks and then enjoy!
Use whichever essential oils you like. I like to use .5 ounce each of tea tree, rosemary, and peppermint. See the section above for more information on equipment.No time to DIY? My (Katie's) Wellnesse Cleansing Shampoo is another great option!