The binder, is the film-forming component of paint. It is the only component that must be present if the binder material is suitable for application. Many binders are too thick to be applied and must be thinned. The type of thinner varies with the binder. The thinner is also called the vehicle, because it makes it possible to transfer the binder to the surface with a brush, roller or sprayer. Components listed below are included optionally, depending on the desired properties of the cured film.
A clear paint like a varnish contains primarily the binder and the vehicle plus some dries. If you add pigment to provide color and opacity to a varnish you create an enamel. Enamels therefore contain the three primary type of ingredients found in all paints - 1) binder, 2) vehicle, 3) pigment.