What is the difference between a colorant and a pigment? It all depends on the size of the particles

What is the difference between a colorant and a pigment? It all depends on the size of the particles

Colors are divided into two groups that should not be confused, although a priori they seem the same to us: colorants and pigments . Dyes are substances that dissolve in water or any other solvent and are used to dye fabrics, to draw on paper and to color food.

Pigments, however, having particles larger than those of colorants, do not dissolve, but rather disperse in the liquid, and are used both for painting and a base for cosmetics.

Brown Van Dyck

Another way to summarize it is the one proposed by Riccardo Falcinelli in his book Cromorama :

In other words, the juice extracted from the plants is a colorant with which the fabric is soaked, and is fixed afterwards so that it does not fade with washing; the earth or ground stones are pigments, and are mixed with other substances such as plaster, egg and oil to make pastes that can be applied by brush.

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The first pigments that humans use are the earth , because obtaining them was relatively easy: it was enough to excavate. They have been used since ancient times to paint or to change the appearance of artifacts. On the other hand, substances suitable for coloring paper, food and fabrics are extracted from plants : from saffron, for example, many shades ranging from yellow to orange are extracted.

Other inks come from the animal kingdom , such as red from the cochineal, which today is also one of the most widely used food colors, marketed under the name E-120: gummy bears, fruit juices … even Strawberry Frappuccino from Starbucks (until vegans protested and stopped using cochineal to start using synthetic additive).

All colors, therefore, have very unique names, such as Van Dyck brown , cadmium yellow, ultramarine blue, Sienese. For example, there are three types of white: zinc, titanium, and lead. These names evoke not so much the chromatic appearances as their origin.

Tierra de Siena , from the town where once this ferrous mulch was abundant; brown Van Dyck, in homage to the painter who best used that dark tone; Cadmium yellow, because it is made from cadmium sulfide … somehow, their names are certificates of provenance.