Egg tempera is the most powerful and reliable traditional painting medium that has no substitute. Executed with pigments based on chicken eggs, tempera painting thrived until the end of the 15th century when it was replaced by oil painting. Since its revival in the 19th century, it has been greatly expanded.

As a painting process that incorporates egg yolks to bind pigments together, the artist must mix his or her own paint by combining finely ground pigments, water and diluted egg yolk. The paint is then applied in a technique where the optical laws of egg tempera are observed to achieve the unique surface of egg tempera. In addition to mixing the paint, the artist also has to prepare the canvas.

Beginners think of egg tempera as a magical medium capable of solving all of the problems they encounter with drawing and painting. However, egg tempera is very difficult to master. Although it is unlikely that tempera will ever become a mainstream medium, it boasts a large group of devotees, both artists and collectors, around the world.

Characteristics of egg tempera

The term "tempera" comes from "temper" or "tempering," which means to bring something to a desired or usable consistency. In this case, that something is a pigment. Egg tempera is one of the oldest, most versatile and durable methods of painting, generally unaffected by humidity and temperature changes. Tempera emulsions form their own protective surface film and do not darken with age as oil-paint film. Tempera dries rapidly and is water resistant, which means that one application of paint can be rapidly followed by another without color mixing. This unique property is a distinct advantage over ordinary watercolors and allows you to see one color through the other. A red egg tempera wash, for example, can be applied over a blue wash to produce a blue-red or violet color, whereas the result of this procedure with watercolors will create a muddy-brown hue.

Tempera colors can also be scraped off easily and reworked. When applied in thin layers the results are more transparent than transparent watercolor; when applied thickly, the results are opaque, like gouache. After the tempera painting is complete it can be burnished (polished) with agate to add depth and brilliance and to increase transparency, or it can be varnished to look like an oil painting.

Step-by-step process

The first-recorded recipes for egg tempera called for egg whites and were mainly used for illuminating manuscripts on paper or parchment. Since this mixture was brittle, it was eventually replaced by a recipe that incorporated egg yolks, which contain semidrying oils and produce a tougher, more flexible film.

Today, egg tempera (not to be confused with "tempera" or poster paints), consists of egg yolks, water and pigments. The downside to this composition is that the artist must mix his or her own fresh paint every time. The upside is complete control over the paint: If the paint is too intense or too pale, all one has to do is to add more pigments.

The feel of egg tempera on the brush is very special. Each stroke dries almost instantly, allowing the artist to build up layers of tiny hatch marks. When dry, the paint has a golden luminescence due to the egg yolk.

What you need: a smooth piece of wood for support, some brushes, pigments, whiting (ground chalk, gypsum, marble dust or titanium oxide if you can afford it), animal glue or strong gelatin and some sandpaper.

First of all, make sure your board is nice and smooth. Sand it if necessary. Then, take your glue or gelatin and heat up some water in a double boiler. For every one part of water add 1/16th the amount of glue. (Traditional recipes prescribe 1 ounce of glue to 16 ounces of water.) If you make too much glue, it can be stored in the refrigerator for up to one week. After the glue is well dissolved, use it to cover the board. (This process is called sizing.) Apply a few coats, alternating between vertical and horizontal strokes (one horizontal coat, one vertical coat, etc). Let the sticky board dry overnight. Sizing the board prevents it from expanding and shrinking with the changing weather. Once your board is dry, take the leftover glue (or make some more) and heat it up again. This time, add some whiting to it (the amount varies). Apply the whiting like the sizing, letting it dry between coats. You may have to sand the board between coats for a smooth finish. Apply at least three coats.

To make your own paint, crack an egg and separate the yolk from the whites without piercing the yolk. The best way to do this is to pour the egg back and forth between two halves of the cracked shell, allowing the whites to drain out. Once the yolk is separated, put it on a plate or in a bowl and pierce it. Then mix the yolk with an equal part of water and add to the paint (which has been premixed with a small amount of water) until the paint reaches the consistency of melted butter. The exact consistency will vary.

An inkwash over the sketch will secure the light and dark hues into place. To paint with egg tempera, use small strokes. Remember that you can't cover a large area with a single stroke since this kind of paint dries very quickly.

Good trick: egg-oil emulsion

Tempera made with a single egg yolk is not as workable as an egg-oil emulsion. Adding a small amount of stand oil improves the paint's handling properties and increases resistance to cracking, allowing the paint to be applied thickly. Egg-oil emulsions can be used on flexible supports such as a canvas, heavy watercolor paper and thick bristol paper, if applied in thin layers. Thicker layers, like those used in gouache, are workable when built up slowly using many thin layers. Egg-oil emulsions produce a glossier finish than pure egg tempera and dry better. Like egg tempera, an egg-oil emulsion dries very rapidly and can be painted over almost immediately.

You can prepare your own egg-oil emulsions based on the following instructions. (Remember to take extreme caution when using dry pigments.) Egg yolk and linseed oil are combined to create an egg-oil emulsion with an oil paint consistency. Mix one teaspoon of oil with a single egg yolk. Too much oil slows down the drying process significantly and tends to leave a tacky surface. One part of this emulsion can then be mixed with one part of water-dampened pigments.

Egg yolk, stand oil and Damar varnish make a durable and flexible egg-oil emulsion. Mix one egg yolk and one level teaspoon of a mixture of half stand oil and half Damar varnish. Pigments can then be added in equal parts. As with all egg or egg-oil temperas, the surface can be polished with a silk pad when dry. The disadvantage of this egg-oil emulsion is that it very much resembles oil painting, with its inherent yellowing. Venice turpentine can, however, be used as a substitute for stand oil to reduce future yellowing and to improve the clarity of the paint film.

Whole egg and linseed oil is the "lazy" artist's egg tempera, where the egg, oil and pigments are mixed in equal portions. The egg-oil emulsion dries relatively quickly, producing a hard but slightly cloudy, surface.