Under low humidity conditions, the diminished moisture content of hair leads to everyday grooming resulting in considerable build-up of static electricity. That is, hair has an especially low conductivity and so resulting charges are not readily dissipated.

 

Consequently, static build-up can be a major problem during low humidity cold winter months and often an issue during heat styling. Conditioner products can be very effective at reducing static electricity build-up, although there are differing views on how they function. It is likely there is a contribution from lubrication (which reduces the amount of charge build up), and also an increased surface conductivity arising from the deposition of cationic surfactants (which facilitates charge dissipation).  
 
We quantify this benefit using a protocol based on the method of Lunn and Evans (JSCC, (1977), 28, 549-569). Hair tresses are equilibrated at low humidity  and then brushed on a custom-built device. An appropriately placed sensor provides real-time measurement of the static build-up:
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The maximum amount of static generated after cessation of brushing is recorded and the static decay with time can be measured.  The procedure can be modified for products and tools that have an effect on static build-up in hair.