Buttermilk refers to a thick, fermented dairy product with a slightly sour taste. Buttermilk hydrates the skin when applied, as it is high in fats and oils that penetrate the surface. When added to soap, buttermilk creates a sweet-smelling and hydrating skin cleanser safe for use on sensitive skin types. However, if you would like to make buttermilk soap you must take precautions to protect yourself from the ingredients before they are cured.
Freeze 8 cups of buttermilk for 24 hours.
Put on chemical-resistant gloves and pour 5 1/4 cups of lye and 6 1/2 cups of water into a 2-gallon plastic bucket. Lye is a corrosive chemical and it will burn your skin if it encounters it before curing the mixture.
Remove the frozen buttermilk from the freezer and place it into the bucket. Stir slowly with a paint stirrer until the buttermilk melts completely.
Pour 1/2 cup of white sugar and 1/2 cup of sea salt into the mixture. Stir for two minutes or until the sugar and salt are completely dissolved.
Ask an assistant to put on a pair of chemical-resistant rubber gloves and hold a large funnel over each soap mold as you carefully fill them.
Allow the soap to cure in the molds for two months before use.
Purchase chemical-resistant rubber gloves from your local hardware store.