To wash is to remove dirt...

To wash is to remove dirt, and to do so we need to dissolve it…but for example, fat doesn’t dissolve in water. How should we clean it, how does the detergent act? Maria Francisca Coma has sent us an explanation that may help us understand it.

Water is the best solvent, but fat, a major component of stains and dirt, it is not soluble in water. Here lies the main problem when washing. To make fat soluble in water we must saponify it, emulsify or hydrolyse it and this is the main mission of the detergent. When we wash we have to create the right conditions for these chemical reactions to take place. Otherwise dirt, all or part of it will remain.

Detergents are formed by several chemical compounds. The main ones are the surfactants, also called active material. A surfactant is a compound whose molecules have an unusual property (hydrophilic and hydrophobic at the same time). Thanks to this feature you are able to split fat into tiny particles called micelles and form a colloidal solution with them in the water.

Colloidal solutions are emulsions. The main feature of the emulsions is the equilibrium state. If for some reason it breaks the emulsion disappears. This is because the micelles are particles consisting of a core with an electric charge, surrounded by an ionic atmosphere composed of ions with opposite charge to that of the core; and therefore the electric charge is what achieves balance and maintains the solution .

Micelles are formed when the amount of detergent and temperature are adequate. If the temperature is low or amount of detergent too little, the chemical reaction may not occur. Putting more detergent than necessary, micelles form different types of clusters with part of their electrical charges neutralized and detergent acts/washes less.