The origins of soap

The origins of soap

Everyone needs to stay clean, whether we like it or not. After a rough day on the playing field, a bath with soap gives us that fresh feeling. Soap is wonderful, the way it bubbles and the sweet smell that it has. Apart from bathing, we wash our clothes and clean our utensils with soap. We use soap everyday but do we know the story of soap? It is an excellent example of everyday chemistry in action. 

How soaps work

Soaps help us remove grease and dirt. Soaps have a molecular structure that attracts water at one end and particles that do not dissolve in water at the other. This means that soap sticks to dirt particles. When the soap is washed away it carries the dirt away.

The beginning of the bubbles

The first soap in ancient Babylon 2200 B.C. was made of alkali – a substance that reacts with an acid to form salt and water; cassia oil; and water. In ancient Egypt the soaps of the pharaoh were of animal and vegetable oils mixed with alkaline salts to form soaps.

In ancient Egypt the soaps of the pharaoh were of animal and vegetable oils mixed with alkaline salts to form soaps.

Chemists in fact were one of the first people to produce soaps, making them out of vegetable oils like olive oil, mixed with aromatic oils like thyme and lye (caustic soda).  Perfumed coloured soaps originated in Arabian countries like Iraq. In fact Persian chemist Al Razi was the first to document his recipes for making soap.

Making a modern soap

Soaps similar to what we use today began in 16th century Europe with finer soaps of olive oil. It was only in the 18th century that large-scale production of soap started. Andrew Pears was the person to make the first high-quality transparent soap.

Today, soap is made using a cold process. Here fats like olive oil and coconut oil are made to react with lye. Lye is chemically sodium hydroxide. These oils give the soap different characteristics. Coconut oil for example, can make soap lathery; olive oil is ideal for mild soaps; and palm olive provides hardness. When oil and an alkali are mixed, it forms glycerine and the sodium salt of the fatty acid. Changing the proportions of alkalis and fatty acids makes the soap lathery or transparent.
 

Soap’s molecular structure attracts water at one end and dirt particles at the other.

Removing sodium chloride, sodium hydroxide and glycerol from the soap further purifies it. The process for this is boiling the soap curd and re-precipitating the soap in salt. Once done, water content is removed from the soap and small soap pellets are made.

The finishing touches for a soap

The finishing touch for the soap pellets is to add fragrance in a mixer and passed through a wire screen to refine it further. The final step is to send the soap through a vacuum chamber to remove trapped air and made into a soap log, which is cut and stamped to shape.

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