WEDC Technical Brief No. 8: Making soap

Soap is important in preventing the spread of disease by helping people keep themselves, their clothes and their surroundings clean. In some places, soap is unavailable or expensive. This Technical Brief gives some practical guidelines on a cheap, easy way to make soap on a small scale, using ingredients which are available locally.

The principle: Making soap involves a chemical decompositions of fats and oils into their constituent parts, namely fatty acids and glycerol. The fatty acids combine with an alkali, usually caustic soda, and the glycerol remains free. In the 'cold' process, which is described in this Technical Brief, oil is treated with a definite amount of alkali. The aim is to complete the reaction, which generates its own heat, without any free alkali being left in the soap.