Soap was once for the wealthy only
The origin of soap can be traced to Babylonians around 2800 BC. They had accidentally discovered that boiling animal fat and wood ash produced a substance that made cleaning easier. The first item they washed was wool.
By 1500 BC, the practice had spread to Egypt, to the Phoenicians in 600 BC and the Romans in the first century.
Not only was soap expensive but it was considered for the wealthy in spite of its unpleasant smell.
Manufacturers began combining it with other substances like vegetable oil and alkaline salts.
Saponification
As demand increased in the Roman empire, other surprising ingredients like goats’ tallow and human urine made inroads into soap manufacture.
Centuries later during the Industrial Revolution, new methods of soap manufacturing were devised with the importation of fragrant ingredients from Africa and Asia like palm and coconut oils. Soap became even more popular.
With the discovery of alternative manufacturing methods in the 1800s, soap became less expensive.
In 1879, a French employee of Procter and Gamble accidentally created soap powder after he forgot to turn off a mixer that exposed the mixture to unusual amounts of air. In 1890, William Shepherd first patented liquid soap.
These discoveries were a blessing to major corporations that manufactured soap including Procter and Gamble, Colgate Palmolive, among many others.
Since then, there have been no other major discoveries and the same processes are used for making soap.
While actual production processes may vary among manufacturers, soap production basically involves three steps.
First, oils and fats are combined with water and glycerol in a method called saponification.
Next, the mixture is dried in high temperatures to reduce its water content and lastly, the dry plain soap is mixed with fragrance, colour and other additives and then cut into bars.
Technology used in soap making has undergone evolution; from the batch kettle boiling method used during World War II to the spray drying, agglomeration and dry mixing methods used today.
Spray drying
In the spray drying method, the saponification slur is heated and then pumped to the top of a tower where it is sprayed under high pressure to produce small droplets in order to form granules.
Bleach, enzymes and fragrances are then added to it.
Agglomeration consists of blending raw materials with liquid ingredients and with the help of a liquid binder to form larger soap quantities.