If you knew what most soap was made of, you might have second thoughts about ever using it. Traditionally, the main ingredients in soap were alkali and animal fat, and years ago manufacturers got the fat right from slaughterhouses. When mixed with water, the fat and alkali combine to break dirt away from surfaces.
No one is quite sure of the origins of soap, although the Romans were reported to be using it or something similar as far back as 600 B.C. However, it was often used as much as a medicine as a cleanser. It was not until the second century A.D. that soap was used primarily as a cleaner, both for bathing and for cleaning surfaces.
The first companies to manufacture soap were found in England around the 12th century, and by the 17th century soap was common, although expensive, often considered a luxury, in France, Italy, Spain, and other parts of Western Europe.
One reason soap was expensive and treated as a luxury was because of the tax collector. There was a great demand for soap, as you can imagine, and everyone wanted it. Tax collectors throughout Europe viewed soap as a golden revenue source, placing high taxes on the product. In fact, soap became so valuable as a revenue source, locking lids were placed on soap-boiling kettles by English tax collectors every night. This helped prevent the manufacture and sale of illegal soap.
The Manufacturing Process
The ingredients used in soap have changed over the years. Animal fat is not used today, having been replaced by fatty acids or vegetable oils such as olive oil, corn oil and coconut oil. This helps eliminate many impurities associated with using animal fats and the potential spread of germs and bacteria.
The kettle process of making soap is actually still used today for some very "special" soap products. However, around 1940 engineers developed a more efficient procedure called the continuous process. As the name implies, the soap is not made one batch at a time, in kettles, but produced continuously. This speeds up production considerably, and technicians have more control over the final product.
The next stage of the continuous or kettle process is to pour the soap into molds. This gives it its shape. In some cases, the molds are cooled in freezers to help speed the manufacturing process. The final step involves cutting the soap into bars and wrapping it.
What About Milling?
Anyone who knows much about toiletry soap has heard the expressions milling and milled soap. This is a higher quality soap that lathers up better, has a finer consistency, and often has perfumes and other ingredients added to it to make the soap more luxurious.
After the soap has hardened or been cooled, it is fed through sets of heavy rollers called mills that crush the soap and knead it. The soap is then pressed and cut into bars, stamped, and wrapped. The final product is a lot more effective and useful than what was made 2,600 years ago, and thankfully, the special taxes are gone, so it is a lot less expensive as well.