Soap manufacturing – unchanged for hundreds
In short: Soap is usually made by the reaction of renewable oils and fat (tallow, coconut oil, palm oil) and alkalies (sodium or potassium hydroxides). Once the glycerin is removed you have a base soap which can then be refined with added ingredients and fragrances.
Base soap is produced in three steps – saponification, salting
In the first step, animal and vegetable fats are melted and brought to a boil in a stainless steel kettle together with an alkali.
This process, which is referred to as saponification, initially forms an emulsion. In the beginning the fat reacts slowly with the alkali to produce a mixture of soap and glycerin. At this point the chemical reaction speeds up. The final addition of a small overage of sodium hydroxide guaranties a complete saponificaton.
In step two, salt is added in order to separate the soap and the glycerin. After a certain amount of time, the soap swims to the top. The watery substance at the bottom of the kettle is filtered out in order to recycle the remaining glycerin.
The third step in the production of base soap is called pitching or finishing. The soap is boiled a second time and a new batch of alkali and salt is added to the kettle. After approximately 48 hours the mass separates into three layers. The first layer contains the base soap and layers two and three contain impurities and most of the alkali.
A portion of the water must then be removed from the warm 63% soap mass that is removed from the kettle. Today this is done in a highly technical vacuum or expansion chamber. The soap mass leaves the dryer with an approx. 80% fatty acid content – the quality standard of a good toilet soap.
This base soap – or active washing substance – can then be finished with added ingredients such as fragrances and perfumes according to a variety of compositions.