DIY Cold Process Soap

DIY cold process soap relies on a chemical reaction called saponification, which occurs when lye (sodium hydroxide) is mixed with oils. This process transforms the liquid oils and lye mixture into a solid, stable bar of soap.

While it is called cold process, you do need to carefully heat your oils just enough to melt solid fats and to bring them to a proper temperature. Once mixed with the lye water, the saponification process generates its own heat without requiring external cooking.

The primary danger in cold process soapmaking comes from handling lye, which is highly caustic and requires safety gear like goggles and gloves. However, as long as you carefully follow safety protocols and measure your ingredients precisely, it is a safe home project.

After molding, cold process soap must sit for 24 to 48 hours to harden before it can be cut into bars. The bars then require a curing period of roughly 4 to 6 weeks to allow excess water to evaporate, creating a harder, longer-lasting bar.