Color, Light, and the Art of Emulsion
Opaque and transparent layers create vivid color, depth, and finely controlled modeling.
Egg tempera is one of the oldest and, at the same time, most versatile techniques in panel painting. However, the term does not refer to a single, definitive recipe. At various times, “tempera” has been understood to encompass a wide range of water-dilutable binders and emulsions. In addition to pure egg-yolk tempera, there are whole-egg tempera, egg-white tempera, egg-oil emulsions, and so-called “fat tempera.” Historically, glue, gum, and casein paints were also considered part of the large family of tempera paints.
In his standard work Materials and Techniques of Painting, Kurt Wehlte therefore distinguishes between “natural egg emulsion,” “artificial egg emulsion,” and gum, glue, starch, casein, and oil tempera. This classification alone demonstrates that tempera is less a single material than a system of different binders and painting methods. Kurt Wehlte: Materials and Techniques of Painting
Pure Egg Yolk Tempera
The most basic form of egg tempera consists of egg yolk, water, and pigment. The egg yolk itself is already a natural emulsion: it contains water, proteins, and fats, which are bound together by lecithin. Diluting it with water creates a fine, easily controllable binder.
This tempera is referred to as “lean” because no additional drying oil or resin is added to it. It is therefore not fat-free—the natural lipids of the egg yolk remain a component of the paint.
Pure egg yolk tempera dries quickly. It allows only limited blending of wet paint tones, as is common in oil painting. Instead, form and space are created through a series of carefully placed brushstrokes and thin layers of paint. Transparent layers allow light to shine through from the light-colored ground; more opaque layers define form, contours, and highlights.
The paint derives its depth not from its thickness, but from the interplay of its layers.
Too high a proportion of egg yolk can make the surface glossy, brittle, or difficult for subsequent layers to adhere to. Icon painter Katherine Sanders describes the simplest emulsion as “plain egg yolk with a little water,” but at the same time points out how much experience is required to achieve the correct ratio of emulsion, pigment, and water. Katherine Sanders: Techniques of Icon Painting
Whole-Egg Tempera and Egg-White Tempera
In whole-egg tempera, both egg yolk and egg white are used together. The added egg white alters the flow, binding power, and surface finish. The paint often appears slightly leaner and tighter than pure egg-yolk tempera. Depending on the pigment, dilution, and painting surface, it can dry to a matte or slightly silky finish.
Pure egg white—also known as “glair”—was used particularly in book illumination, for fine decorations, and for highlighting individual areas. It forms a comparatively hard and sometimes glossy film, but is less suitable for building up a multi-layered panel painting from start to finish.
Egg-Oil Tempera and Tempera Grassa
So-called “fat tempera” is known in Italian as tempera grassa. A drying oil—and occasionally a resin varnish—is added to it. Egg yolk or whole egg acts as an emulsifier, binding the water-based and oil-based components together.
As the oil content increases, the paint becomes smoother. It dries more slowly, can be blended for longer, and allows for softer transitions. At the same time, the surface takes on a richer, sometimes glossier appearance. The painting technique gradually approaches that of oil painting, but—as long as the emulsion remains stable—it can still be diluted with water.
“Tempera grassa” does not refer to a specific historical recipe. Under this name, a wide variety of mixtures consisting of egg, water, drying oils, resins, waxes, or soaps were used. Particularly in the late 19th and early 20th centuries, numerous tempera systems emerged through which artists sought to combine the luminosity and quick drying of water-based paints with the suppleness of oil painting. A study of art technology demonstrates how broadly the term “tempera” was interpreted at the time and how varied the compositions of the available mixtures were. Tempera Painting 1800–1950: Experiment and Innovation
Max Doerner viewed the growing number of complicated tempera recipes with marked skepticism:
“An emulsion should be simple in composition.”
Although complex mixtures of oils, resins, glycerin, and other additives might initially be pleasant to paint with, in the long run they could lead to unstable or unpredictable layers of paint. Doerner’s call for simplicity therefore remains relevant to this day: Every ingredient affects drying time, gloss, elasticity, adhesion, and aging behavior. Max Doerner: Painting Materials and Their Use in the Painting, 1922
Egg Tempera in Icon Painting
In Byzantine and Orthodox icon painting, pure egg yolk tempera remained in use for centuries. Finely ground pigments are mixed with carefully prepared egg yolk and applied to a light-colored, absorbent chalk ground. A publication by the Orthodox Church in America describes how mineral pigments are finely ground and then mixed with prepared egg yolk. Orthodox Church in America: Materials for Icon Painting
Even within icon-painting traditions, there is no single, universally binding recipe. Some icon painters dilute the egg yolk exclusively with water. Others use wine, vinegar, or small amounts of alcohol. What matters is not the additive itself, but the mastery of the emulsion and the successive layers of paint.
The characteristic luminosity of many icons arises from the combination of a light ground, transparent layers of paint, and increasingly lighter highlights. The light is not merely applied to the surface; it seems to emerge from the gradual build-up of the paint.
My Work with Egg Tempera
For my quince portraits, I deliberately work with a simplified form of egg tempera: pure egg yolk and distilled water. On the carefully prepared, mineral-based chalk ground, the pigments can be applied in opaque, semi-opaque, and transparent layers.
Shadows, glazes, leaf veins, spots, and blemishes are not added as external details. They emerge within a slow process of image-building, in which each layer reacts to the one before it. The quick drying time of tempera allows for clear decisions; its transparency lets earlier stages of the painting shine through the later ones.
In this way, egg tempera combines precision and openness. It can sharply define a contour while simultaneously creating a transition from numerous barely visible layers of color. In this manner, the painted fruit gains volume, space, and an almost human presence.
For me, egg tempera is not a historical effect technique. It is a painting style of controlled light.