Put on the goggles and rubber gloves. This is very important because lye burns.
Fill the pitcher with 8 oz. distilled water.
Weigh the glass container. Add enough lye so the container plus the lye equals the weight of the container plus 3.35 oz. For example: If the glass weighs 4 oz., the weight of both the glass and the lye should be 7.35 oz. The weight has to be exact.
Add the lye to the water very slowly and carefully. Avoid splashing. Stir. The water will turn cloudy and then clear. The lye solution will heat up. It may even start bubbling. Stir until the lye is completely dissolved.
Set aside to cool in a safe place until the temperature is 100 degrees Fahrenheit. Use a thermometer to check the temperature.
Mixing With Oils
Weigh the oils and add them to the metal pot. Heat oil to 100 degrees Fahrenheit.
Add the lye solution to the oil while stirring with the electric hand-held mixer or blender turned off. The lye and the oils both have to be the same temperature. The mixture will turn cloudy. Turn the blender or mixer on low and blend until the mixture starts to thicken.
Add the essential oils.
Continue to blend until the mixture is thick. It is still caustic, so don't handle it.
Pour into the mold. Tap the mold gently to remove air bubbles. Throw a towel over the mold and let it sit in a warm, not hot, place for 24 hours. Remove soap from the mold and cut it into bars. The bars should ripen for six weeks to harden, but can be used after 48 hours.