The cohesion of a paint film depends on the nature of its constituents and heterogeneousness. The binder is usually an organic polymer which responds not only to requisites of transparency, but also to the necessary elastic properties. More precisely: a film of siccative oil takes on viscoelastic behavior, as do many linear polymers. The pigments, instead, are mainly mineral particles of various sorts and dimensions characterized by their hardness. After drying, the paint film will be flexible, while aging will make it lose its initial characteristics and become more brittle and subject to breakage.