How Does Soap Work?

History of Soap Soap was one of the first chemical compounds ever made by man. The first soaps were probably the saps of certain plants, such as the Soap Plant (Chlorogalum pomeridianum), whose roots can be crushed in water to form a lather, and used as a shampoo.

When was soap first used? Some hypothesize that even prehistoric man had a primitive form of soap.  Soaps have been excavated in clay cylinders that date back to 2800 B.C. By 1500 B.C. Egyptians medical scrolls recommend a soap made from alkaline salts and animal and vegetable oils for skin conditions.

+ = What is saponifcation? Later, people learned that fats would react with alkalies in the ashes left over from a fire to produce saponified compounds Saponification is commonly used to refer to the reaction of a metallic alkali (base) with a fat or oil to form soap.

How is soap made today? Today, soaps are made from fats and oils that react with lye (sodium hydroxide). Solid fats like coconut oil, palm oil, tallow (rendered beef fat), or lard (rendered pork fat), are used to form bars of soap that stay hard and resist dissolving in the water left in the soap dish.

The Structure of Soap

How does soap clean your clothes? Because of that dualism, soap molecules act like a diplomat, improving the relationship between water and oil. How? When soap is added to the water, the hydrophilic (polar) heads of its molecules stay into the water (they like it!), while the long hydrophobic (nonpolar) chains join the oil particles and remain inwards (escaping from the water).

What is a Micelle? In that way, they form circular groups named micelles, with the oily material absorbed inside and trapped. A micelle is a spherical body, which arises when amphiphilic molecules aggregate.  These present their hydrophilic 'head' groups to the aqueous solvent and their hydrophobic 'tails' are buried within the micelle.

What other ingredients go into soap making? Glycerin: Emollient and texture enhancer BHT: anti oxidant to preserve the oils from going rancid Sorbitol: Helps make glycerine soaps more transparent Titanium Dioxide: Makes soap opaque PEG-6 methyl ether: Surfactant, detergent, emulsifier to make dyes and perfumes blend evenly