In modern and specialized literature, priming indicates the superficial and finishing layer of a preparation, characterized by little thickness and a smooth and uniform surface, in order to facilitate the spreading of brush strokes. Depending on its characteristics, the primer gives the paint layers a transparent or opaque base color.
Traditionally, the term primer is used in a more generic sense to indicate the preparation with plaster and glue of a surface to be painted, however with the intention of distinguishing it from the mestica, which is characterized by the presence of an oily component. However, the sources tend to use the terms “imprimitura” and “mestica” as synonyms, as documented by the references between the two entries in the vocabulary of Filippo Baldinucci (1681).
Bright preparations with colored primers or preparations directly mixed with earths or other opaque pigments are not uncommon to find on canvas paintings after the mid-Sixteenth Century. While preventing the maximum brightness that can be obtained through the transparency effects of the colors on the white background, these preparations provide a medium tone as a basis that allows the artist to work simultaneously in both the light and dark registers. Immediately, with a few brushstrokes, the image is rendered in three dimensions with particularly marked chiaroscuro effects conforming to the taste of the time.