Encarnaciones is a technique for painting flesh tones that is closely related to the oil painting technique used by artists working on canvas, such as Bartolomé Esteban Murillo. After the estofado work was completed on the garments of Saint Ginés de La Jara, encarnaciones layers were applied following the steps below.
1. Size—The flesh areas were coated with glue size (made from sheepskin), when the surfaces were coated for estofado.
2. Yeso mate—A single layer of yeso mate—yeso grueso (gesso) powder that has been slaked (soaked in water) until it becomes pure white and silky smooth—was applied to the finely carved head, hands, and feet.
3. Underlayer—Paints were prepared using a variety of pigments (see below). The first pinkish beige layer of oil paint was composed of lead white, cochineal (powder ground from the cochineal insect), and charcoal.
4. Highlights—The blue of the veins was achieved by adding a small amount of indigo to lead white and charcoal.
5. Final layers—A final translucent coat of pinkish beige oil paint was applied over the veins. The reddish details such as the knuckles were highlighted with additional cochineal.
Preparing Paint for Encarnaciones
Preparing oil paints was a painstaking process in Luisa Roldán's day. Colors came from a wide range of sources that were each processed in distinct ways. Painter Tomás de los Arcos probably acquired the pigments for Saint Ginés, but apprentices likely prepared the paints.
Obtaining the Pigments
White was made by exposing metallic lead to vinegar (a mild acid) and manure (a source of carbon dioxide, heat, and moisture), creating a layer of corrosion. The corrosion was scraped from the lead and ground into a fine white powder.
Black was made by heating wood in a closed kiln until it was partially burned, producing charcoal. When ground, this pigment is a gray-black color.
Red was derived from the cochineal insect (Dactylopius coccus) that lives on cactus. Adult females were harvested, dried, then ground to produce a dye. The dye was then combined with a mineral support, transforming it into a pigment. The cochineal used on Saint Ginés was imported to Spain from Mexico.
Indigo was made by fermenting indigo plants in water. It is likely that the painter of Saint Ginés used indigo produced in India.
Making and Storing the Paint
The pigments were ground into very fine particles with a muller (stone pestle). They were then mixed with thickened linseed oil to produce paint. Linseed oil was obtained by pressing seeds of the flax plant (Linum usitatissimum). It was then boiled or left to stand in the sun to thicken. To quicken the setting of the oil, a drying agent such as lead white was added.
To keep the prepared paints from drying out, they were sometimes stored in pigs' bladders. A hole was punched in the side of the bladder and sealed with a removable plug.