Ever run out of shampoo and considered using soap instead? While it might seem like a quick fix, it’s not the best choice for your hair’s health.
What is soap? Soaps are mixtures of sodium or potassium salts of fatty acids and the process of making soaps is known as saponification.
The problem with hard water and soap
Soaps are mixtures of sodium or potassium salts of fatty acids and the process of making soaps is known as saponification.
In most of Britain, the water is naturally hard. This type of water contains a higher amount of naturally dissolved magnesium and/or calcium salts. When hard water and soap are mixed, the magnesium ion reacts with soap molecules and forms a solid material called a precipitate (soap scum), which does not dissolve. This soap scum reduces the ability of the soap to make lather.This hard water and soap residue can stay on the scalp and hair shafts reducing the shine and texture.
Soap’s impact on pH
The natural oils produced by the scalp has a pH of about 5.5 and this creates an environment where fungi and bacteria don’t thrive.The pH of soapy water is around 10-12 which makes it alkali. This can increase the over growth of natural yeast that live on the scalp resulting in seborrhoeic dermatitis and dandruff.
Why shampoos have a different pH
Importantly, if a shampoo or liquid is alkaline (where pH is greater than 7) and applied on the scalp and hair, the cuticle of the hair softens and gets lifted which exposes the cortex. This can cause damage to the hair fibre.
When the cuticle is tightly packed and not lifted, it allows the hair fibre to move freely and reflect light better resulting in shine causing the hair to feel smooth and well conditioned. That is why a good shampoo will always have a pH of around 5.5 which is the pH of the skin and scalp and is better for hair health than using soap.
One observational study done in India and published in the Indian Journal of Dermatology in 2013 looked at the pH of soaps and shampoos sold. Only 3% of soaps had a pH corresponding of skinTherefore, using soap on hair has a detrimental effect.
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