Cold Process soap is, in short, soap that is made from scratch. Oils and butters are combined, then emulsified, with Sodium Hydroxide (lye) and water. Colorants, fragrance or essential oils, and additives can be mixed in before or after emulsification, depending on ingredients. After the “soap” is poured into a mold, it undergoes a chemical reaction called saponification over the course of about 48 hours. This process is when lye turns the oils and butters into salt and glycerin – when the “soap” officially becomes soap! While it is technically safe to use after this time because the lye is no longer present, there is still some excess water that hasn’t yet evaporated. The soap would likely end up being quite soft, and wouldn’t last very long. For this reason, it’s best to let soap cure for 4-6 weeks. The pH level will continue to lower, producing a more gentle bar.