Those who’ve been reading here for awhile or have delved into the archives know that I’ve sometimes experimented with a traditional painting medium called tempera grassa. TG was most commonly used in the 15th and 16th centuries; it represents a transitional medium between egg tempera and true oil painting. TG consists of pigment mixed with an emulsion of egg and oil. Since the 16th century, TG has been fairly obscure—the best recent example would be the 20th century Italian master, Pietro Annigoni.
In the 19th century (especially in Germany), painting recipes were developed that involved various combinations of tempera ingredients, often including some combination of egg white, whole egg, linseed oil, stand oil, dammar varnish, stand oil, and turpentine. You can find many such recipes on the internet with a few simple Google searches. I’ve usually avoided these relatively complex recipes in favor of simple emulsions of egg yolk (the traditional binder for egg tempera) and linseed or walnut oil, mixed with pigment/water paste.
Recently, I ran across a web reprint of Egg Tempera Painting, Tempera Underpainting, Oil Emulsion Painting: A Manual of Technique, by Vaclav Vitlacyl and Rupert Davidson Turnbull. Published in 1935, it is a compendium of various tempera techniques. One that caught my eye is a recipe they call “putrido.” Putrido is one name for tempera grassa (because it starts to smell bad after a few days). They say that this is based on a recipe from an old manuscript found in Venice. For all I know it’s what was used in the Renaissance.
Take whatever quantity of dry color you wish to prepare. Divide it into two equal parts. Rub up one part with yolk of egg only into a fairly stiff paste. Rub up the other part with sun-bleached linseed oil, to about the consistency of ordinary tube colours. (To save time or trouble, it is possible to use ordinary tube oil colours, but to be sure of your ingredients, it is always advisable to grind your own colour in oil.) The part that is rubbed up with oil may be slightly larger in quantity than the part rubbed with yolk of egg. Then take the two parts so prepared and grind them together, preferably on the marble slab. It will be found that when these two parts are put together, the resultant mixture will stiffen at once into a very stiff paste, too stiff to be easily rubbed. This may be softened down by the addition of either water, emulsion, or linseed oil. If you wish to use the Putrido in its leaner form, add either water or the emulsion (Medium Fat Emulsion), but if you wish to paint with it as an oil paint using oil as the medium, then thin it down with oil. In either case, add the water, the emulsion, or the oil very slowly, only a few drops at a time, until the paste becomes a smooth cream easily handled on the marble slab.
I find this to be pretty interesting. It is a recipe that is similar to what I’ve done before, is simple to make, doesn’t involve solvents, and uses egg yolk (rather than the white or the whole egg), with which I am more familiar. They suggest that adding a small amount of oil of clove will preserve the paint mixture and allow it to be kept for some time (although not indefinitely). I expect that storing them in a refrigerator, especially in warm weather, would be a good idea. The oil of clove would also act as a retarder for the oil component of the paint, causing to dry more slowly. That could be a good or a bad thing, but I expect one would have to wait between layers for the paint to dry. You could try to balance the retarding effect of the clove oil by adding a small amount of lead napthenate, but that makes for a more complex reaction than I am really comfortable with.
I’ll have to try this recipe soon. I have a large painting that I started in tempera and then stopped work on. It might make an excellent underpainting for this TG recipe.