Begin by carefully measuring out the sodium hydroxide and filtered water separately.
In a well-ventilated area, slowly add the sodium hydroxide to the water while stirring until it is fully dissolved. Be cautious as this mixture will heat up.
In a separate container, measure the castor oil and virgin coconut oil, then combine them.
Once the lye solution has cooled down to around 100°F, slowly pour it into the oils while mixing continuously.
Blend the mixture using an immersion blender until it reaches a light trace.
If desired, add the essential oils and mix thoroughly.
Pour the soap mixture into molds and allow it to set for 24 to 48 hours.
After the soap has hardened, remove it from the molds and cut it into bars.
Let the bars cure for about 4 to 6 weeks before using.
