A
manicure is subject to a lot of abuse as the wearer goes about their
daily life (opening jars, cooking, typing on a keyboard). For repeat purchase of a nail polish, it must be able to stand up to this type of use. As well as the adhesion properties mentioned above, the stiffness and toughness of a polish are all extremely important.
An overly stiff, brittle polish would be undesirable as it would break when a nail is bent when opening a soda can, for example. The low stiffness is important for the polish to follow the nail as it bends. A high strain to failure is also crucial, or the polish film would break under the slightest deformation.
