Tempera grassa was a common painting medium in the 15th century. Since then, not so much (though with a few notable exceptions). It’s an interesting medium to work with.
Tempera grassa is an emulsion of egg and oil (an emulsion is a liquid in which tiny drops of another liquid are suspended). Egg yolk is a natural emulsion that incorporates oil into its makeup fairly easily. You are already familiar with an egg-oil emulsion—it’s called mayonnaise. Tempera grassa is essentially mayonnaise made with a drying oil such as linseed or walnut.
To make a simple kind of tempera grassa, separate an egg yolk and put it into a small cup. Measure the volume of yolk, then measure out the desired volume of oil. Add just a few of drops of oil to the egg, mixing thoroughly as you do so. Add a little more oil and continue mixing. Repeat, adding oil a few drops at a time, until all of it has been blended in.
The amount of oil to use will depend on your preference; anywhere from a few drops to an amount equal to half again the amount of egg will work. The more oil, the more slowly the paint will dry and the more it will handle like oil paint. If you are just starting, try five parts egg to three parts oil (which produces a moderately egg-rich mixture). If you’ve worked with egg tempera, an egg-rich formula will handle in a familiar way. Once you have mixed the egg and oil into an emulsion, you will want to add some water, blending it in a few drops at a time in the same manner that you added the oil. I have had good results with a mixture of 5 parts egg to 3 parts oil and 1.5 parts water, but you should feel free to experiment.
This substance is your painting medium. It will keep in the refrigerator for a week or so, depending on how much oil it contains (throw it away and clean the container thoroughly if it starts to smell). Mix in a couple of drops of water before each day’s session to compensate for evaporation. You can make paint with it by mixing together approximately equal amounts of medium and a paste of pigment and water. You can thin the paint with any desired amount of water; the important ratio is that of medium to pigment.
Raw pigment powder is available in some larger art stores and from places like www.sinopia.com. Prepare it by putting the powder into a small jar, adding distilled water, and shaking. Wear a dust mask when working with pigment powders.
Some artists use tube watercolor or gouache paint instead of pigment for egg tempera and tempera grassa. I haven’t tried that (you may have noticed that I’m kind of a purist with these things), but I don’t see any reason why it wouldn’t work.
It is important get the ratio of pigment to binding medium right with tempera grassa. Practice on test pieces until you can consistently make acceptable paint. Tempera grassa paint made with too little medium will feel powdery once it dries. You can correct this by painting over it with thinned medium or with thinned egg yolk. Tempera grassa paint made with too much medium is difficult to work with and dries poorly. After the water and egg dry, it will have a crumbly, sticky feel if you run your hand over the surface. Don’t paint additional layers over it in this state, as you will probably get poor adhesion. You can either wait for the oil component of the paint to harden, which can take a day or two (or more with an oil-rich formula), or you can carefully scrape the paint off with a knife and start over. It is also true that tempera grassa mixtures very occasionally fail to form stable emulsions, becoming gummy and unworkable. The paint will then refuse to dry for very extended periods (up to a couple of weeks). I don’t know why this occurs; I’ve had this happen only a couple of times. If the medium seems intractable or the oil and egg combine incompletely, throw it away, scrape off any paint you may have applied, and start over.
I am the author of the book titled, “Oil Painting with ’ Calcite Sun Oil’ “. The focus of my book is to provide a method of oil painting that is Safe and Permanent…and that can be EASILY done without use of any hazardous materials such as Solvents, Varnishes, Resins or Driers.
please review my website….www.calcitesunoil.com for details.
reference this posted article, the author here describes the ‘tempura grassa’ and its use, problems, advantages and some historical reference.
My goal in writing this response, and in authoring my book, is not to be confrontational, but rather to be educational and to share the knowledge I have gained from my experiences and experiments.
The first problem with the article is the suggestion to use only certain brands of tube oil paint… i.e. ‘softer’ ground paint. I know that brand type is not important, as neither is softness nor ‘hardness’ of the grind.
Another problem with the articles advice is to use a mixed emulsion containing egg yolk, and then advising different experiments by further adding resins and water to the mix. These never ending experiments are unnecessary… and can result, like the article says to “…scrape…and start over’.
Use of the correct emulsion is important, and t is the simplest thing in the world to make and use. My book describes the two emulsions that offer different properties and results..but still so simple to make. You can forget about the method in the article describing adding ‘drop by drop’ until mixed. The emulsion is made in seconds, with a quick shake.
Eliminate all egg yolk, all resins, all solvents, all driers and concocted painting mediums , and especially any water, from the emulsion. Again, it is so very simple, and the simplicity allows freedom to paint… safely and with permanence….and with a method that allows you to ” achieve the paint quality of the Old Masters”.
thank you, louis
Louis,
I have not read your book. Obviously, my experience with tempera grassa is different than yours. I have mainly used emulsions with raw pigments, not tube oil paints. I’ve found that works much better for me.
I have also had better experiences with yolk as a binder than with glair (egg white). That may come from my work in plain egg tempera, which is normally done with yolk.
Historically, panel painting was done by tempering pigment with yolk (using, for example, Cennini’s tempera recipe), while illumination on parchment or paper was done with glair. The analyses that I’ve read indicate that tempera grassa was normally made with yolk (for example, Baldini’s analysis of Botticelli’s “La Primavera”).
There are plenty of references from the 19th century and later to emulsions made with egg white, but if you’re going to refer back to the Renaissance Old Masters as your basis (as in references to the Van Eyck’s painting medium), I’d be very interested to know what sources you use to justify excluding yolk and instead using glair.
Hi David, If you read my book, you will find a detailed description of two very different egg-oil emulsions…one named ’ viscous emulsion’ and the other named, ’ non-viscous emulsion’. The difference is in the oil used. Suffice to say, they have distinctly different properties and uses.
Your term, ’ raw pigments’, must mean ‘dry pigment powder’. Use of dry pigments with Emulsions is not the method I describe in my book. My reference is to either hand ground ( self made) oil paints or store-bought tube oil paints. Again, the difference in the two is in the oil used, and the properties are vastly different.
But, since you’ve not used Emulsions with manufactured tube oil paints……, then when you do, if you follow the instructions in my book, you will see you can eliminate all the solvents, driers, varnishes, painting mediums, driers… which are hazardous to your health and to your painting’s health. I noted you had previously written ( and I agree) that early oil paintings did not use solvents. My book covers that.
I do not disagree with the use of egg yolk with Egg-Tempera as the medium. But, when using an oil medium…then the viscous, oily, yolk is excess oil…. simply proven by my experiments,it is not needed.
Yes, historically…Cennini, Botticelli, et al… the ‘Tempera’ medium requires the yolk…the glair is not sufficiently viscous, nor pliable, nor is it a strong enough binder for any paint with body, therefore, as you say, with thin paint for illuminating books, it is just fine.
Now, for use with oil paints….. the glair is the perfect liquid ( once mixed with the oil to make the emulsion/ which is effortless and quick) that will do a number of very important things to oil paint. (1) it increases adhesion of layers (2) It eliminates wrinkle of impasto (3) It is the paint thinner (4) it is the ‘oil out’ that allows micro-fine details. (5) It prevents drip, trickle, crawl. Again, my book gives the full explanation of making, mixing, using, these two emulsions which I call,” the ‘Wonder Medium”.
The Van Eycks…. yes. Pre-Italian Renaissance by just a few years….. The Van Eycks did not discover oil painting as Vasari wrote. Modern scholarship has proven Vasari wrong in that comment, as we know the oil medium is an ancient medium, but a medium with great disadvantages…..until the Van Eycks arrived. We do know the Van Eycks ‘perfected’ the oil medium. The proof is in their works. Vasari also wrote of the Van Eyck ’ secret’. Its all in the Vasari multi volume writings, ‘Lives of the Artists’. Look up the volume on Antonello Da Messina…. there Jan Van Eyck is called ‘John of Brughes’. Its a nice story, but the reader is left with NOT knowing the Van Eyck ‘secret’. My book describes this ‘historical account’, and the basis of why I believe Jan’s secret was… glair…. to make the Emulsions. I believe Jan and Hubert knew the egg so intimately, that they varied the mix ratios…and the different oil viscosities… to create their oil paint medium.
My book expresses the results of my experiments on this concept. I think I offer oil painters today… a safe and permanent medium for oil painting. The two emulsions, described in my book, are used in conjunction with my formula of ’ Calcite Sun oil’. To answer your request for ‘sources’ I use to justify exclusion of yolk and use of glair, I must state, Vasari did not know the ‘Van Eyck secret”, because had he known it, he would have recorded it, and I would be quoting him as the source.
sincerely, louis
Louis,
Yes, by raw pigments I am referring to powdered pigment, or powdered pigment that has been mixed into a paste with water.
It’s been my understanding that yolk, not glair, was used not just with straight egg tempera, but also in emulsions with oil in the form of tempera grassa.
I’d also like to point out that, while many of his contemporaries painted in combinations of oil and egg, some of Van Eyck’s paintings appear upon chemical analysis (by, for example the National Gallery) to have no spectral protein spike. This would suggest that they are painted in pure oil paint, without any kind of egg (or glue) emulsion).
HI DAVID, In response to your comment, pasted here in quotes:
MY RESPONSE: I recall reading on your site you are now reading some new books, you cite “Rembrandt The Painter at Work”, by Van De Wetering, but you said you had not yet read it. Once you do you will see that newest evidence is that egg was added to the oil by Van Eyck and REmbrandt.
In the Van Wetering book, look on pages 225–243, (with specific reference on pages 239–240 ) for scientific evidence of Van Eycks use of a proteinacious ingredient mixed with his oil. If you are a practicing painter, you will know first hand the value of egg glair mixed with the UNREFINED oil to create an emulsion, and its many benefits for controling the viscous paint.
Louis,
I’m in Missouri at the moment, away from my books. When I get back, I’ll post some information from the second edition of the National Gallery book on Rembrandt that, as I recall, conflicts with the statement you cite on the Van Wetering book.
DAVID, Yes,..Im aware of the conflict. I have both the old first edition and the new 2006 edition…But, the scientists are always in conflict..and always changing their minds…..they usually are not artists/ painters and have no experience.. … incidentally, you will not find in the National Gallery Publications ONE COMMENT that the oil the Old Masters used was UNREFINED !!!!…..Its because they do not know — just as you did not know– and they have yet to learn the difference of the properties of UNREFINED and ALKALI REFINED OILS. The differences are vast. My book has broken new ground in this very important area.
….one thing for sure……. once used, you will know the immense value of proteinacous additive to viscous oil paint in order to make it behave ( so it does not drip and spread, yet allowing easy blending, and other important benefits). And you will know the value the emulsions add to controlling the paint…and how they allow the complete elimination of the hazardous solvents, resins, varnishes and driers.= sincerely, louis Velasquez
Hi David, Additional comment on the ’ experts’ findings.
Once you read the copy of my book I sent you and once you do the experiments, with the true Old Masters’ linseed oil I sent you, as my book instructs, you will arrive at a fuller understanding of WHY the solvent based “painting mediums” came into being… and of the very important properties of the UNREFINED, cold pressed , sun thickened Linseed oil I have written about. As to the “experts”, they have a long history of contradictions based on varioius reasons. Professor Dr. Ernst Van De Wetering, author of ‘REMBRANDT: The Painter at Work’, is probably the only one of those ’ experts’ who is a real painter. He has given demonstrations at the Rembrandt Huis Museum in Amsterdam, demonstrating the materials and techniques of Rembrandt and other 17th century Dutch masters. For those that do not know, Dr Van De Wetering is the head of the Netherland’s , ‘Rembrandt Research Project’, a government sponsored academic study group ( with highly controversial decisions) whose goal was to separate the ‘real’ Rembrandt paintings from those not by the master.
sincerely, Louis
Its all very interesting : I guess the idea is to stay within the ball park area of handling the medium. But I must say that oil that has been boiled slowly in litharge has a lighter and more saponified feel to it than the sun thickened oil, and Pacheco himself states that he grinds all his darks with it and reserves the sun thickened oil for the white and the blue only. This would increase drying time considerably as any lead added on the bed of the sun oil will do, and the grease would be fluffier on the ammalgamationcomposite of all the oils combined; certainly the emulsion could be cherry gum as Rembrandt often used and hide glue too but the glair is dead on in similarity. What about heating the oil in lime and scumming it, and then straining, adding ceruse and putting in the sun, or best is in a brass jar or on a cermaic plate.
Im trying crushed eggshells into the putty enamel and getting a mother of pearl effect when trace amounts of white lead is added.
Has anyone tried calcining balls of putty mixed with alum to make a good cheap white?