The History of Soap

Soap making became a craft in Italy by about 700, and by 800 Spain was a leading soap maker. Soap making began in England around 1200. Nicolas Leblanc, a French scientist, found that lye could be made from ordinary table salt in the late 1700's. Following this discovery, soap began to be made and sold a prices that almost everyone could afford.

Many early settlers in North America made their own soap. They did this by pouring hot water over wood ashes to make the alkali potash. They then boiled the potash with animal fats in iron kettles to make soap. The soap cleaned well, but much of it was harsh and smelled bad.

The soap industry in North America began in the early 1800's. Some people collected waste fats from others and made soap in large iron kettles. They poured the soap into large wooden frames for hardening. After the soap hardened, they cut the soap into bars that were sold from door to door. Manufacturers have made big improvements in the mildness, color, fragrance, and cleaning ability of soaps since the early 1900's. Soap making is still a craft in the United States, as well as all over the world.

How Does Soap Affect the Body?

To understand how soap works you have to understand the construction of a soap molecule. A molecule, to refresh your memory, is the smallest particle of a substance that has all the parts (properties) of that substance. Molecules are made up of smaller particles called atoms. The main atoms in a soap molecule are carbon, hydrogen, oxygen, and a metal, such as sodium or potassium.

During soap making, long chains called fatty acids collect fats, and oils begin to minimize. When you clean, the water end of the soap molecules sticks into an oil that your skin produces called sebum. As the water circulates during the washing process the soap molecules carry away the oil and the dirt that is in it.

Detergents work on the same principle as soaps, except that the fatty acid is replaced by another kind of hydrogen-carbon chain that generally will not react with minerals to form a film.


This is the chemistry page. On this page you will learn all of the details of how soap works. You will also learn many new soap terms. Soaps are water-soluble sodium or potassium salts of fatty acids. Soaps are made from fats and oils, or their fatty acids, by treating them chemically with a strong alkali.

Fatty Acids

Fatty acids are the components of fats and oil that are used in making soap. They are weak acids composed of two parts: A Carboxylic acid group consisting of one hydrogen (H) atom, two oxygen (O) atoms, and one carbon (C) atom, plus a hydrocarbon chain attached to the carboxylic acid group. Generally, it is made up of a long straight chain of carbon (C) atoms each carrying two hydrogen (H) atoms.


An alkali is a soluble salt of an alkali metal like sodium or potassium. Originally, the alkali used in soap making were obtained from the ashes of plants, but they are now made commercially. Today, the term alkali describes a substance that chemically is a base (the opposite of an acid) and that reacts with and neutralizes an acid. The common alkalis used in soap making are sodium hydroxide (NaOH), also called caustic soda, and potassium hydroxide (KOH) also called caustic potash.

How Soaps are Made

Saponification of fats and oils is the most widely used in soap makings process. This method involves heating fats and oils and reacting them with a liquid alkali to produce soap and water (neat soap) plus glycerin. Some soaps are made from tallow or lye. Tallow is fat taken from cattle or sheep, and lye is an alkali substance.