Heat transfer in human hair.

Abstract

In the process of daily grooming, human hair often undergoes heat treatments. These treatments create temperature gradients inside individual hair fibres or bundles of hair which can lead to hair damage. Mathematical models were built for heat transfer in a single hair as well as thin tresses of hair during blow drying. Mathematical analysis led to temperature profiles suggestive of fast transfer of heat in a single hair mainly through conduction. However, in a hair assembly, the process involved both conduction and convection leading to a slower rate of heat transfer. Penetration of heat to the centre of the hair assembly took minutes rather than seconds. This model is useful in understanding hair damage potential in styling hair with high temperature devices such as flat irons and processes which involve deforming hair at relatively high temperatures.