People use many methods to wash the clothes. Usually, after adding the soap, they beat the clothes on the stone, or beat it with the paddle, scrub it with the brush or the mixture is agitated in the washing machine. Why is agitation necessary to get clean clothes?

Soap, water, and oil are all made of molecules. A soap molecule has two ends: a hydrophobic tail (repelled by water, attracted to oil/grease) and a hydrophilic head (attracted to and mixes with water). Because oil and water don’t mix, soap positions itself at the interface: the tails embed in the oil/dirt, while the heads stay in the water.

This arrangement forms tiny spherical structures called micelles, with the oily dirt trapped inside and the hydrophilic heads on the outside, dispersed in water like a colloid. Agitation (scrubbing/stirring) helps detach these micelles from the surface (e.g., fabric or skin), and rinsing washes them away—leaving the surface clean.