Egg Tempera

May 25, 2009

Egg tempera portrait by Botticelli

Egg tempera Medici Portrait by Botticelli

Egg tempera is an time tested technique, especially well loved by panel and icon painters.  It renders flat graphical shapes and fine precise detail quite well.  Softer gradual modulations are possible but take practice and patience.  The unvarnished final work has an almost chalk-like finish to it.  This technique formed the backbone-skill to any medieval or renaissance painter’s tool chest. The twentieth century has witnessed its revival with Andrew Wyeth being perhaps its most famous spokesman.

For anyone wishing to ask experts geeky questions about the medium check out the MITRA forum. In the past there has also been the Society of Tempera Painters (whose informative forum is currently offline). The Tempera Society had a well established site and forum, documenting many aspects of the process as well as related techniques. In its absence, I’d suggest picking up a good book and starting in. The online version of Daniel Thompson’s, The Practice of Tempera Painting is one of the most extensive sources around.  Cennini is charming even if a bit antiquated in his terminology and procedures.  If you are looking for something more general in order to get started, try Ralph Mayer’s “The Artist’s Handbook of Materials and Techniques”, Reed Kay’s “The Painter’s Guide to Studio Methods and Materials”, or “The Materials of the Artist and Their Use in Painting” by Max Doerner.  All are tried and true comprehensive source books for the craft of painting.

Egg tempera is a paint made from an emulsion of oil and water.  The final paint film is not as flexible as oil.  Thus, to avoid cracking, the painting is executed on a firm and stable panel not on a stretched canvas.  At the moment, I use egg tempera primarily as an underpainting.  The links here on the right offer some info – by no means extensive – about how I prepare my gesso and panels.

Be sure to supply yourself with a good collection of dry pigments – avoiding poisonous materials whenever possible.  You don’t want to breathe in toxic dust. By grinding your own paints you get to know the specific characteristics of each pigment – opacity/translucency, saturation, hydrophobic or philic, chromatic nuance. Online suppliers are very helpful if you do not live in a large city with a big art supply store. Get a thick piece of frosted plate glass and a glass muller. Otherwise a pallette knife and wooden painter’s pallette can suffice in a pinch. Grind up a small amount of each pigment you want to use in distilled water, making a smooth paste. The pastes can be stored in plastic film containers for short periods without drying out. To extend that drying out time I usually insert a piece of sponge at the top of the jar. Keeping it moist prolongs the life of the pigment paste.

The Egg:
Locate as fresh an organic an egg as you can. Crack the shell carefully in half without breaking the yolk. Carefully move the yolk between shell halves to isolate the yolk from the white (all the while protecting the egg yolk membrane from puncture).  Let the white albumen drip away. Pass the yolk back and forth between the palms of the hands in order to dry it off.  Roll it across a piece of absorbent paper towel for further drying.  Eventually you should be able to pick up the yolk by it’s sac.  Hold it over a small clean jar (empty jelly jars from hotels are great for this) and pinch the bottom.  The pure yolk will drip out.  Add an equal amount of distillled water, cap, and shake it. Store in the refridgerator.

Tempering the Paint:
On your glass palette add equal amounts of pigment paste and egg yolk. I use a palette knife to measure a “bean” of pigment paste and a small pipette to measure the same by dipping into my prepared egg. Mix until smooth. If you have already ground up your pigments in distilled water, then adding the egg binder now is easier and requires much less grinding. Some pigments will require more yolk, others less. To make sure you have tempered your paint correctly, Take a moistened sable brush, dip it in your newly mixed paint and lay a stroke on a nearby piece of window glass. It should dry quite quickly. Then take a one-sided razor blade and gently scrape the paint swash off. It should maintain its own consistency and curl off like a ribbon. If you have not added enough egg the pigment will return to powder and flake off. If you have added too much egg the paint film will lack chromatic saturation. Let experience be your guide. Soon you will get the knack of it.

When you are satisfied that you have tempered your paint correctly, transfer this mixture to a painting cup. I use a nested set of porcelain dishes that have a top cover. The tempered paint is rather thick, too think for painting, so at this point it is important to add additional water in order to arrive at the right mixture of pigment/yolk. How much water? Apparently, that doesn’t really matter. If your paint has been tempered correctly you can (if you wish) dilute it with large amounts of water so as to paint with many fine watercolor-like washes. As you work, it may seem as though the color is not building, but be patient and you will see that it does.

Sable brushes dipped in this watered down paint will be too saturated for the painting stroke. Using your thumb and forefinger press the excess liquid out until the brush renders a clean full stroke without leaving behind a blob of paint at  the end of the motion.

Egg tempera does well with many light thin strokes. Do not immediately rebrush a stroke. Let it dry, then add another level. Because it dries so quickly this is usually not a problem at all. In this way soft transitions can be achieved. But is is important to let your brush dance over your whole painting. Do not obsess in any one area, if it has not thoroughly dried it can become overworked and lift off earlier levels of paint, creating a hole that is difficult to repair. Stay light and playful, attentive to the whole work. Each artist decides how to use this medium to his/her own ends.

The Panel

May 7, 2009

The Panel:
A firm non flexible ground is necessary for painting with egg tempera.  On good linen canvas, the oil medium can sustain flexing and shrinking, but egg tempera cannot.  If one chooses to work exclusively in oil, canvas may be the ground of choice.  As I prefer to use a mixed technique, painting on panel is my preference.  Additionally, I find the smoothness of the surface very sensuous.

Of the choices readily and economically available to painters these days, my personal preference is good quality, plywood panels.  They are heavier than Masonite but in the long run, more absorbent.  They do not warp, and the fine crackles that can occur in the gesso from slight wood expansion can be avoided either by obtaining a high quality piece of plywood from a cabinet maker or by gluing a thin layer of fine linen fabric to the board before the first coat of gesso.