The invention of soap is, from an evolutionary standpoint, a recent invention, emerging during the Middle Ages. Centuries later, a substance called soda ash, or sodium carbonate, improved the cleaning power of soap and allowed industrial production to create an effective, inexpensive product.
Soap is the chemical reaction between sodium hydroxide and a fat or oil. Once the chemical reaction completes, what is left is glycerin (a moisturizer) and sodium salts of fatty acids (soap).
Sodium carbonate soaps help remove insoluble oils from materials, such as motor oils, human sweat stains and vegetable grease.
Sodium carbonate soaps are ideal for hard water conditions, which have an acidic environment. Sodium carbonate creates an alkaline medium, ideal for detergents to remove unwanted, insoluble stains.
Sodium carbonate soaps help eliminate the magnesium and calcium rings around the bathtub, by neutralizing the mineralized ions in the water.
In 1791, Nicholas Leblanc, a French chemist, patented a process for making soda ash (sodium carbonate) from common table salt. Industrial soap makers were able to produce large quantities of inexpensive, quality soap.