Solvents may be used as a binding agent for the preliminary sketch, the preparatory work for a painting. They give a diluted colour, good for laying down a base for the colour, but also promote binding between the future pictorial layer and the canvas. Mediums are additives that allow you to adapt or customise a work by modifying the texture of the paste without changing its appearance too much. We always bear in mind the rule that advises “fat over lean” and not the other way round. Varnishes offer indispensable protection for the conservation of any work, and delay the ageing process in oil paintings.