Glossary
Cold process
Making soap by mixing oils and a lye solution at moderate temperature, then curing for weeks.
Cold process is the most common from-scratch soap making method. Oils and a lye solution are each brought to a similar, moderate temperature, then combined and blended until the batter reaches trace. Saponification finishes gradually inside the mold over the following day or two, not during mixing.
Because the reaction is not rushed with added heat, cold process gives makers more working time for swirls, layers, and embeds than hot process does. The tradeoff is that bars need several weeks of curing afterward so the reaction fully completes and excess water evaporates before the soap is ready to use.
When starting out, a simple recipe with two or three oils and a moderate superfat is easier to manage than a complex blend, since it behaves more predictably at trace. A common beginner mistake is unmolding or using bars too early, before the multi-week cure is finished, which leaves them softer and shorter lived than a fully cured bar.