Independent buying guides for soap making

Soap Making Glossary: 14 Terms Explained

The words that show up in soap making specs, reviews and how-to guides, explained without jargon.

Cold process
Making soap from oils and lye at moderate temperatures, then curing the bars for about 4-6 weeks.
Cure
Letting cold process bars dry so excess water evaporates, giving a harder, longer-lasting bar.
Related: Best Curing Racks for Handmade Soap
Fragrance oil usage rate
The safe maximum percentage of fragrance for skin products, published by the supplier for each oil.
Related: Best Fragrance Oils for Handmade Soap
Gel phase
A heating stage in fresh soap that can make colours more vivid. Some makers encourage it, others prevent it.
Hot process
Cooking soap batter until saponification completes, giving a rustic texture and a shorter wait before use.
Lye
Sodium hydroxide (NaOH) for bar soap or potassium hydroxide (KOH) for liquid soap. Always wear gloves and eye protection.
Related: Best Lye for Soap Making
Lye calculator
Software that computes exact lye and water amounts for a recipe. Never guess lye quantities.
Melt and pour
Pre-made soap base you melt, colour, scent and pour. No lye handling, great for beginners.
Related: Best Melt and Pour Soap Base
Mica
A shimmering mineral colourant used in soap and cosmetics.
Related: Best Mica Powder for Coloring Handmade Soap
SAP value
The amount of lye needed to saponify one gram of a specific oil.
Saponification
The chemical reaction between fats and lye that produces soap and glycerin.
Soda ash
A harmless white powdery film on the soap surface, usually removed with steam or planing.
Related: Best Soap Planers for Clean, Even Bars
Superfat
Extra oil left unsaponified on purpose, commonly around 5 percent, for a milder bar and a safety margin.
Trace
The point where soap batter thickens enough that drizzles leave a visible trail on the surface.
Related: Best Stick Blenders for Soap Making