Soapmaking

Soapmaking is the craft of producing soap by saponifying fats or oils with an alkali. In a typical reaction, triglycerides from animal or plant fats react with sodium hydroxide for solid bars or potassium hydroxide for liquid soaps to form soap and glycerin.

Soap has ancient roots in the Mediterranean and Near East. Early soaps were made from ashes and fats, then improved with refined oils and more controlled alkalis. The term Castile soap refers to a style developed in Spain using olive oil. With the rise of industrial chemistry in the 19th and 20th centuries, soapmaking became a scalable manufacturing process, while artisanal and small‑scale methods remained popular for specialty products.

The basic inputs are fats or oils, an alkali, and water. The proportions and choice of fats influence hardness, lather, and moisturizing properties. Common methods include cold process, hot process, and melt‑and‑pour. In cold process, a lye solution is mixed with melted oils, the mixture thickens to a trace, is poured into molds, and then cures for several weeks to complete saponification and improve mildness. Hot process uses heat to accelerate saponification, allowing earlier use. Melt‑and‑pour starts from a pre‑made soap base that is melted and customized with additives.

Safety and quality are important. Lye is caustic and must be handled with protective gear in a well‑ventilated area, with water added to lye rather than the reverse. Finished soaps are typically milder after curing, and pH can vary but is usually in the mildly basic range. Soapmaking yields products for cleansing, skincare, and specialty applications, and differs from detergents in its reliance on fatty acid salts derived from fats.