Asked by: Aaron Billson, Cannock
The shape of your hair reflects the shape of the molecules of which it is made. These are long keratin molecules (a type of protein) that resemble a long spring, with several ‘springs’ wrapped around each other like a twisted rope. The strands are held together by strong chemical bonds called disulphide bonds, while the coiling of the individual molecules is maintained by much weaker hydrogen bonds. The disulphide bonds can only be broken with heat (as happens in ‘permanent waving’ hair treatment), but hydrogen bonds are affected by water, so the individual molecules can change their shape temporarily when wet.