Soap as a hair cleanser

The purpose of this thesis was to investigate the challenges concerning the use of soap based products for hair cleansing. The thesis was commissioned by a Finnish natural cosmetics manufacturer, Vihreä Kosmetiikka Finland Oy, whose most popular products are soap based shampoo bars. Soap is a natural surfactant, but it can cause hair stickiness to some users. The reasons why some of users get the stickiness while others do not was investigated. In addition, the methods of removing the stickiness were investigated as well.

In the theoretical part, hair chemistry and structure was reviewed, concentrating on the outer layer of the hair fibre, where hair cleansing preparations affect. The chemistry of soaps and surfactants, and the manufacturing methods of soap were also reviewed. Soap easily reacts with minerals in water and forms scum, which can cause hair stickiness. Vinegar can be used to remove the soap scum residues from hair, and also as a conditioner. The experiences of the shampoo bar users were investigated with a survey. Questionnaires were sent to the users and 217 responses were received. The most useful answers relative to the survey were found from the open response feedback obtained from the respondents.

Based on the theory and survey, the main factors affecting hair stickiness were previous hair treatments, hair length and hair type as well as water hardness. Based on the thesis, suggestions for improvements were made to the company.