About Tempera

15. The medium of employment for the project will be tempera.

Today, we find paints called tempera, or poster paints, on art store shelves quite commonly. This tempera vulgaris is decidedly not the same as classical tempera, which we will be using here; it is more like bodycolor, or gouache, which is essentially watercolor mixed with a substance such as chalk or diatomaceous earth to make it opaque. This common tempera, found frequently in elementary school art classes, is far enough away from classical tempera that it's a toll call.

Indeed, when speaking of classical tempera we usually say egg tempera. The word tempera itself, according to author Ian Sidaway in the highly commendable reference book Everything You Ever Wanted To Know About Art Materials, (a link to this exists on our references list to Amazon so you can buy it) is:

...the word given to the technique whereby pigment is prepared for painting, or "tempered" by mixing with egg yolk and distilled water.

Anyone who's ever tried to clean dried egg yolk off anything knows full well what a durable and sticky emulsion this can be. Tempera gives a thin, hard layer of color that is very durable but is not very flexible; typically period artists painted on a rigid surface, such as wooden panels.

A Bit Of Media History

Tempera was the dominant art medium since the decline of encaustic, which apparently happened around the same time as the fall of the Roman empire (about the 3rd Century AD) and held sway until the development of traditional oil paint in the 15th Century (Vasari seems to credit Jan Van Eyck with discovering it; certainly it seems that he at the very least rediscovered and perfected it). All easel painting done before then was done in egg-based tempera, including all the great and well-known masters of the time.

Making Tempera

While egg tempera is available in tubes pre-made, in order to copy the experience of our medieval cousins as closely as possible, we will be making our own. The general look to be as follows (llustrations excerpted from Sidaway's book):

A basic recipe for tempera emulsion that we might concievably use is as follows:

• 3 parts egg yolk
• 3 parts distilled water
• 1 part linseed oil

Add the linseed oil to the egg yolk a drop at a time, using an eyedropper, and stirring all the time. Once mixed, add the distilled water in the same way, stirring gently until throughly mixed.

A pertinent question here is how much egg to use. One of the points that all the references we've seen make repeatedly is that mixed tempera does not really keep well, or if does is more trouble that it's worth to do, so the recommended amount to make is what one will need at a single session. Sidaway suggests one egg should do the trick, so according to the above recipe, if we'd use one egg yolk, we'd use an equal volume of distilled water, and 1/3rd of that of linseed oil.

Purists hold that to stay to the true one must limit themselves to only yolk and water, but experimentation down the years has proven that the addition of ingredients such as linseed oil, "stand oil" (linseed oil that has been heat treated to polymerize the oil molecules) or varnish can give benefits such as improved workability, flow, or slow drying. During a recent Google search, we were able to find out a small handful of different recipes, so with experience and experimentation, artists can be pretty sure to find an emulsion recipe that works for them.

Care must also be taken in the tools used to prepare the emulsion and keep the chances of contamination at thier minimum. Glass and ceramic vessels are recommended; tools and hands must be scrupulously clean, and metal tools are not recommended for mixing the emulsion.

Preparing the Yolk

Preparing the yolk for use is a simple process but likely not many have been exposed to it. We ourselves recall our mother separating yolk from white by cracking the egg and tipping the contents between the two shell halves. This stage of the process is quite similar.

Once cracked, pour the contents into clean hands. Roll the egg's contents from hand to hand. As you do so, the white will drain off (presumably you have a receptacle under your hands at this point), leaving you in short order with the yolk, alone. Dry this yolk by either rolling it around on your hand, or carefully rolling it onto a paper towel.

At this point comes the time to drain the yolk from its natural container. Hold the yolk carefully by its sac (this is why you want to use absolutely the freshest eggs you can find; not only are fresh eggs more workable, but the yolk sac is strongest when the egg is fresh), puncture it with a scalpel or a craft knife, and drain the contents into a glass jar or dish.

Follow the instructions on whatever recipe you're using to mix in distilled water and whatever oil or varnish you'll be using, and your emulsion will be ready for the pigment.

Preparing the Pigment

Dry pigments are sold as finely ground powders, but a common approach to improve the properties of the resulting tempera is to grind them with a small amount of distilled water to produce a creamy paste.

The paste is ground on a ground glass plate using a ground glass muller, then adding to the emulsion a little at a time.

Once the pigment is successfully mixed with the emulsion, the tempera is ready for use.

By way of final observations, we are still researching exactly how one would go forward from using the mixed tempera. From what we've seen, a little goes a long way, and some colors can be preground and kept for a while, while others should only be mixed on the palette at the time of use. Different recipes require different strategies for storage, and some colors are more powerful than others meaning you'll use more of some pigments and less of others.

Along the way, we've found some interesting web-based references. Check our list of links in the sidebar, and following this is a list of references we've consulted while putting this article together.

Reference Links:

1. Society of Tempera Painters on making tempera
2. Watercolorpainting.com's tempera reference
3. Daniel Smith's tempera making page (includes valuable information on how the dry pigments behave)
4. Some Tempera History (Brandywine Museum Article)
5. More Tempera History (Courtesy VanAken Artist Colors)
6. Scribal Writes #7, Article on Making Tempera

Tags: tempera, making tempera, tempera painting

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Email Subscriptions Enabled

9. I've tried the email subscription box myself and it seems to work okay. I noticed an error message on subscribing, but I don't think that will prevent anyone from getting updates.

Coming up, we're going to be taking a deeper look at what goes into the making of vellum. We will be looking in depth at the information the Lady Tegan has graciously provided me. Also, my instructor has directed me to get a first hand view if possible, and that's in the works.

Stay tuned to this scroll for further details.

Tags: vellum, coming up

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What is Vellum and Parchment, And What Makes Them Durable?

7. In the current phase of my research I am being directed to learn what I can about the basic materials that medieval scribes used to produce the works they produced. The current focus is on the "paper" they drew and wrote on.

I say "paper" because, unlike today, the material that our medieval cousins used to write on, or as we'll say in these discourses the substrate, the more upmarket varieties of said substrate were made from animal skin.

The following comes from the common knowledge as I am aware of it, and as a long time user of artistic-grade papers.

Today we can buy parchment and vellum for our work from commercial vendors, and these are manufactured out of plant products, notably cotton. If we want to acquire something that has archival value, we want as high a "cotton rag" content as possible; one of the by-products of wood-pulp-derived paper substrate is that the resulting paper is of an acidic character, which actuallly causes the paper to essentially consume itself over time. Anyone can check this out for themselves; mass-market "paperback" books that are any more than perhaps ten or fifteen years old have 'gone yellow'; this is the paper in the first stages of this breakdown. Particularly fragile are "pulp" magazines and books made with this paper from, say, the 1950s and before. This are immediately obvious from thier nearly-amber color and the extreme fragility of the paper. There is no saving these in thier original form.

By contrast, parchment and vellum substrates are made from components more akin to cloth than wood pulp, and are as near as possible chemically neutral. 100% rag vellums and parchments have, with proper care, a practically indefinite shelf-life, or as near as makes little difference. They can be damaged with improper handling, and inattentive care can cause them to degrade, certainly; but if attention is paid to handling and storage, they can be considered, for any practical purpose, permanent records.

Medieval Substrates

The medieval scribe and heraldic artist also had vellum and parchment available to them. They were, however, not made from plant product; they were made from animal skin.

Local SCA member Lady Tegan of Conwy, in a very informative handout on the subject, has this to say about parchment:

Parchment, by definition, is the skin of an animal, usually sheep or goat, prepared as a surface n which to write or paint. Parchment has been in continuous use for over six thousand years. Pergamum, in Asia Minor, is traditionally regarded as the place where parchment is said to have been invented in the early part of the second century BC. The source of this tradition is Pliny’s Natural History, Book IV.

Exactly why medieval scribes and artists used parchment when papermaking was, while maybe not widespread in Europe possibly not unknown (with the Egyptians and Chinese having made paper of various kinds from plants for centuries) is a bit beyond the ken of this author, at least for the moment. One of the Lady Tegan's sources provides a clue which we can note in our passing:

During medieval times some of the books produced in English monasteries were written on parchment of outstanding quality, especially in respect of whiteness, even appearance, smooth flexible handle (sic) and excellent writing properties. This was due mainly to the use of modified compositions known as stanchgrain - thin pastes made by mixing lime, quicklime, and flour with egg-white and milk.

Parchment was simply the best writing substrate available, and therefore presumably seen as fitting grounds to support scrolls, heraldic art, and the like.

Defining the Terms

At this time, we figure that a more complete definition of terms would be of use. For convenience sake – and for the moment – we will help ourselves to the definitions provided by Wikipedia.

The definition of parchment is:

thin material made from calfskin, sheepskin or goatskin. Its most common use is as the pages of a book, codex or manuscript. It is distinct from leather in that parchment is not tanned, but stretched, scraped, and dried under tension, creating a stiff white, yellowish or translucent animal skin. The finer qualities of parchment are called vellum. It is very reactive with changes in relative humidity and is not waterproof.

We see here that vellum is more or less simply an upmarket type of parchment. The Wikipedia definition of vellum reads:

Vellum (from the Old French Vélin, for "calfskin") is a sort of processed animal hide that is thin, smooth, durable and was used in the pre-printing age to produce written works in the form of a scroll, codex or book.

An important point to note here also is that the chief difference between parchment/vellum and leather – also made from animal skins – is that leather is tanned, whereas parchment and vellum are not.

Perhaps one can say that parchment has many uses, but vellum is specifically for the making of written works and art, and probably those of great value meant as historical records.

Tags: parchment, vellum, writing substrates

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