Clean and healthy with the help of chlor-alkali

Washing hands is the basic rule of personal hygiene, which we have adopted since childhood and which has gained a recent role in combating the COVID-19 pandemic. What you may not know is that chloro-alkali chemistry is used in the manufacture of soap, helping to keep us healthy.

Sodium hydroxide, known as caustic soda, is an essential product of chloral-alkali chemistry. It is a whitish solid, easily soluble in water, extremely reactive and corrosive. And it serves as a basic component to react with an oil and obtain soap, through a chemical reaction called saponification.


Caustic soda is mixed with certain oils, which can be olive oil or soybean oil (for softer soaps), but also coconut oil, palm oil and even animal fats. As the hot liquid fat reacts with caustic soda, it begins to "saponize" and thicken. Dyes and perfumes can be added, and then the mixture is placed in molds, where it continues to react, generating heat. When the soap is colder, the bars can be cut and wrapped, but the saponification process continues for a few weeks, until all the caustic soda has reacted with the oils. This is the process used, even to make the so-called “natural soap”.


Interestingly, the final bar of soap ends up not containing any sodium hydroxide, therefore it’s used a large amount of oil to prevent it from becoming too alkaline, which could irritate the skin.


At Bondalti, caustic soda is supplied in bulk at concentrations of 32% and 50%, or in solid form, in 25 kg bags.


Sodium hydroxide is not the only chemical used to make soap. Potassium hydroxide, another key product of chloral-alkali chemistry, is also used to make liquid soaps.