The cold saponification is a traditional method used to make soap. It involves the transformation of fatty substances (in our case, vegetable oils and butters) into soap under the action of a strong base (lye for the creation of solid soaps or potash for solid soaps). In addition to soap, this chemical reaction also produces vegetable glycerin, a fatty substance naturally present:
Fatty substance + Strong base (sodium hydroxide or potassium hydroxide) = Glycerine + Solid or liquid soap.
This traditional soap-making method is a slow chemical reaction, which takes place at room temperature (between 27° and 45°C), followed by a lengthy and natural drying process. It is the combination of the fatty acids from the melted oils and fats with lye (sodium hydroxide) that generates heat and thus facilitates the saponification process. This stage takes approximately 48 hours. This is the necessary time frame for the chemical reaction to occur on its own, naturally.
Furthermore, this transformation is referred to as a "complete reaction", meaning it will cease once one of the reactants used is exhausted (oils or lye/potash). Generally, for a cold-process soap to be used, there should be no trace of lye left. The reaction will therefore stop when all the lye has been consumed and there is an excess of oils: this ensures that there is no lye left in the final soap.
The soap thus obtained is then referred to as "superfatted" with this surplus of non-saponified oil. This superfatting can be explained in two ways: either by reducing the lye , which involves using less of it, or by adding oil or vegetable butter at the end of the preparation. At Typology, we have opted for the second method: thus the indication "8% superfatted" means that the soap is composed of 8% of fatty substances not transformed into soap and glycerine. This provides greater softness, and nourishing and softening properties to the soap.