Soap; from humble beginnings

Poster Created By: Nasi Abdullahi and Ali Jaffari

Chemical Equation of Soap

Soap is produced in a process known as "saponification". This is a fancy term used to describe the neutralization (Dbl displacement) reaction between the acid and base to form a salt, in this case, soap is actually known as a salt. (Soap-Making Resource, 2008-2015)

To form the cleaning agent, a fat or an oil needs to reacts with a base known as alkali (formally known as sodium hydroxide= NaOH), This chemical reaction produces soap and glycerol in this equation;

"fat/oil + NaOH -----> glycerol + salt (soap)" (AUS-e-TUTE, 2014)

Manafacturing Information

Soap was manufactured around the 1700’s by boiling a solution of ash which was collected by wood and mixed with animal fat. When boiled it created a foam to rise to the top of pot (which was normally used to make soap), when it had cooled in turned to a dense soap. It is later said that a French soap maker had an alternative for using caustic soda from table salt to replace the ash from wood; he removed sodium hydroxide from sodium chloride, and began to spread this new method.

Nowadays, fat and alkali (sodium hydroxide) is used and to change or modify the smell, color, or texture of the soap. Perfumes are also added into the soap to give it a fresh scent. The process, fats and alkali are melted and heated by steam coils from inside the kettle, then brought to a boil, and then salt is added to the mixture to bring the soap to the top and the glycerin to the bottom, where it is extracted. This begins the process of “strong change”, where the kettle is brought to a boil once again to turn any of the excess fat to soap. The final step is called pitching and in this step water is added and once again brought to a boil, then “neat soap” is formed at the top which contains 30% water and 70% soap, the lower layer which is called “nigre” mainly consist of dirt salt and most of the water is left behind while the top is taken away.

Waste Treatment

After the reaction of soap is complete, the remaining nigre soap must be removed of dirt, dust and other impurities. Most of these said impurities are INSOLUBLE; they cannot be dissolved with solvents like water. The main method of getting rid of these by-products was discovered by a man named Ashton T. Scott in the 1940's. His idea was the use of a centrifuge device that filtered the by-product out of the nigre soap.

This method is still used today by many soap producers. His method provided an easy way to get rid of dirt and grime found in the reaction in a short duration of time. (Ashton T. Scott, 1942)


Soaps and Saponification. (2014, August 6). Retrieved November 30, 2015, from

How Is Soap Made? Learn the Science and the Art of Saponification. (n.d.). Retrieved November 30, 2015, from

Scott, A. (1942, November 17). Removal of impurities from soap nigre - SHARPLES CORP. Retrieved December 2, 2015, from