Water is a vital component of the hair.  Moisture levels have a marked effect on many different hair properties such the water-set and the ease of styling the hair, hair swelling and surface roughness, development of frizz and flyaway, and hair tensile strength. Water uptake and loss is also linked, technically speaking, to hair porosity. However, the technical measurement of hair porosity towards water with DVS, and the consumer definition of porosity are not necessarily the same thing.

Dynamic Vapor Sorption (DVS) is a gravimetric technique that be used to measure hair water uptake and loss and create water sorption isotherms. DVS data can be used to investigate the effects of various damage insults and hair treatments on water absorption and desorption

DVS is not usually recommended for the support of hair moisturization claims. Consumer perceived hair moisturization is not linked to water content, but to surface conditioning and to perceived smoothness and softness (see further reading).

DVS is a technique that is very sensitive to changes in sample presentation, and to instrument settings. TRI has many years of experience in this method and can assist with getting robust and reproducible data.

TRI has three DVS instruments, all from Surface Measurement Systems: DVS1, DVS100 and DVS Intrinsic.