Editing Tempera (section)

==Technique==
Tempera is traditionally created by hand-grinding dry powdered [[pigment]]s into a [[paint|binding agent]] or ''medium'', such as egg yolk, milk (in the form of [[casein]]) and a variety of plant gums.

===Egg tempera===
The most common form of classical tempera painting is "egg tempera". For this form most often only the contents of the [[egg yolk]] is used. The [[Egg white|white of the egg]] and the membrane of the yolk are discarded (the membrane of the yolk is dangled over a receptacle and punctured to drain off the liquid inside). The egg yolk is diluted with water and used with pigment. Some kind of remedy is always added in different proportions. One recipe uses vinegar as a preservative, but only in small quantities. A few drops of vinegar will keep the solution for a week. Some egg tempera schools use different mixtures of egg yolk and water, usually the ratio of yolk to water is 1:3; other recipes offer white wine (1 part yolk, 2 parts wine).

Powdered pigment, or pigment that has been ground in distilled water, is placed onto a palette or bowl and mixed with a roughly equal volume of the binder.<ref>Mayer, Ralph, 1976. ''The Artist's Handbook of Materials and Techniques'' (3rd ed.). New York: Viking Penguin Inc., p. 228.</ref> Some pigments require slightly more binder, some require less.

When used to paint icons on church walls, liquid [[myrrh]] is sometimes added to the mixture to give the paint a pleasing odor, particularly as worshippers may find the egg tempera somewhat pungent for quite some time after completion. The paint mixture has to be constantly adjusted to maintain a balance between a "greasy" and "watery" consistency by adjusting the amount of water and yolk. As tempera dries, the artist will add more water to preserve the consistency and to balance the thickening of the yolk on contact with air. Once prepared, the paint cannot be stored. Egg tempera is water-resistant, but not waterproof. Different preparations use the egg white or the whole egg for a different effect. Other additives such as oil and [[wax emulsion]]s can modify the medium. Egg tempera is not a flexible paint and requires stiff boards; painting on [[canvas]] will cause cracks to form and chips of paint to fall off.

Egg tempera paint should be cured for at least 3 months, up to 6 months. The surface is susceptible to scratches during the curing process, but will become much more durable after curing. Egg tempera paintings are not normally framed behind glass, as the glass can trap moisture and lead to the growth of mold.<ref>{{Cite web |title=Egg Tempera Misconceptions - Egg Tempera Forums |url=https://www.eggtempera.com/forum-archive/showthread.php@p=6726.html |access-date=2023-01-29 |website=www.eggtempera.com}}</ref>

===Tempera grassa===
Adding oil in no more than a 1:1 ratio with the egg yolk by volume produces a water-soluble medium with many of the color effects of oil paint, although it cannot be painted thickly.

===Pigments===
Some of the pigments used by medieval painters, such as [[cinnabar]] (contains mercury), [[orpiment]] (contains arsenic), or [[lead white]] (contains lead) are highly toxic. Most artists today use modern synthetic pigments, which are less toxic but have similar [[color]] properties to the older pigments. Even so, many (if not most) modern pigments are still dangerous unless certain precautions are taken; these include keeping pigments wet in storage to avoid breathing their dust.

===Application===
Tempera paint dries rapidly. It is normally applied in thin, semi-opaque or transparent layers. Tempera painting allows for great precision when used with traditional techniques that require the application of numerous small brush strokes applied in a [[cross-hatching]] technique. When dry, it produces a smooth [[Gloss (material appearance)|matte]] finish. Because it cannot be applied in thick layers as oil paints can, tempera paintings rarely have the deep color [[saturation (color theory)|saturation]] that oil paintings can achieve because it can hold less pigment (lower pigment load). In this respect, the colors of an unvarnished tempera painting resemble a [[pastel]], although the color deepens if a [[varnish]] is applied. On the other hand, tempera colors do not change over time,<ref>Mayer, Ralph, 1985. ''The Artist's Handbook of Materials and Techniques'' (4th ed.). New York: Viking Penguin Inc., p. 215</ref> whereas oil paints darken, yellow, and become transparent with age.<ref>Mayer, 1985, p. 119</ref>

===Ground===
[[File:Tarlati-polyptych-Pietro Lorenzetti Pieve di santa Maria Arezzo.jpg|thumb|[[Pietro Lorenzetti]]'s ''[[Tarlati polyptych]]'', Tempera and gold on panel, 1320]]
Tempera adheres best to an absorbent [[Ground (art)|ground]] that has a lower oil content than the tempera binder used (the traditional rule of thumb is ''"[[fat over lean]]"'', and never the other way around).<ref>Doerner, Max, 1946. ''The Materials of the Artist and Their Use in Painting''. New York: Harcourt, Brace and Company. p. 230.</ref><ref>Mayer, Ralph, 1976. ''The Artist's Handbook of Materials and Techniques'' (3rd ed.). New York: Viking Penguin Inc., pp. 165, 253.</ref> The ground traditionally used is inflexible Italian [[gesso]], and the substrate is usually rigid as well.<ref>Mayer, 1976, p. 269.</ref> Historically wood panels were used as the substrate, and more recently un-tempered [[masonite]] or [[medium density fiberboard]] (MDF) have been employed; heavy paper is also used.

===Pre-made paints===
Apart from the traditional process of mixing pigment with egg yolk, new methods include egg tempera sold in tubes by manufacturers such as Sennelier and Daler-Rowney. These paints do contain a slight amount of oil to enhance durability within the container. Notable egg tempera artist and author Koo Schadler points out that because of this addition of oil "tubed 'egg tempera' paints are actually 'tempera grassa', an emulsion of egg yolk and a drying oil (generally with other additives, such as preservatives and stabilizers). Tempera grassa has some of the working properties of both egg tempera and oil painting and is a perfectly viable medium – however it is not the same as pure, homemade egg tempera and behaves differently."<ref>{{Cite web |url=https://www.kooschadler.com/techniques/history-egg-tempera.pdf |title=History of Egg Tempera Painting |date=2017-07-18 |website= |last=Schadler |first=Koo}}</ref>[[Marc Chagall]] used Sennelier egg tempera tube paints extensively.