To make solid shampoo you need to combine fats, water and an alkali in a process called saponification.
To make our men's solid shampoo at Tidy we use sodium hydroxide as our alkali.
It is mixed (very carefully) with distilled water to make sodium hydroxide solution, more commonly known as "lye", which is then carefully combined with our mix of organic fats and essential oils to form our shampoo bars.
Both the powdered sodium hydroxide and the lye are highly reactive at room temperature and can cause serious chemical burns if they come into contact with skin or your eyes.
While handling both the powder and solution we wear protective gloves, face mask, goggles and a heavy apron.
It does look a bit Breaking Bad!
When the sodium hydroxide powder is added to the distilled water the resulting solution gets hot, so we make the solution in stainless steel bowls and leave on a heat resistant surface while it cools down.
Once cooled to the right temperature the lye is carefully mixed with a combination of carefully chosen organic fats and essential oils to make our shampoo.
The process is a relatively simple chemical reaction, but does take precise planning and execution to ensure that all of the molecules in the sodium hydroxide solution come into contact with the molecules in our mixed organic fats to ensure they are all consumed in the saponification process.
To make sure that happens we melt the organic fats we use together to make them a liquid. The lye and the melted fats are then blended a specific amount to thoroughly mix the two liquids before they start to harden, forming our solid shampoo bars.
To be doubly sure all of the sodium hydroxide is consumed by the process we use more organic fats than are needed to react with the amount of lye used in each batch. The excess fats are called "super fats" and have the additional benefit of adding extra cleaning and conditioning properties to our finished solid shampoo bars.
Once mixed, while still liquid, the shampoo is poured into moulds where the chemical reaction continues for up to 6 weeks while the bars cure (or set). Once set the bars are tested to ensure all the sodium hydroxide has been converted to shampoo before they are packaged and sent to our customers.
If you'd like to learn more about how we make our men's solid shampoo bars, you can read our blog post "How to make your own solid shampoo for men" where we share the recipe and the method for making your own shampoo bars.