MITRA Forum Question Details

There are several companies (Sennelier, Daler Rowney, Zecchi) that sell commercially produced paints labeled "egg tempera".  These are not, in fact, pure egg tempera paint (if pure egg tempera paint - just yolk and pigment - were put in a tube, it would quickly putrefy!)  Tubed "egg tempera"  is actually an emulsion of egg protein (albumen) and a drying oil.  Such paints would be more accurately labeled as "egg oil emulsion" or "tempera grassa".  Being water-soluble indicates there is a greater percentage of yolk binder than drying oil in the emulsion. (If there were a greater percentage of oil than yolk, it would be solvent soluble).  There is only one way to have pure egg tempera paint, and that is make it yourself.

Tubed, tempera grassa paint is a perfectly fine medium; however it does not have the same properties as homemade egg tempera.  The oil content makes the paint more painterly and a bit more flexible.  It can be applied more thickly than pure tempera, although not as impasto as oil.  If applied too thickly, it will develop cracks. 

Pure egg tempera reached its peak of renown in the 1400s – a time of more tightly rendered, linear, representational imagery.  So those qualities, to an extent, are not inevitable to egg tempera; they're, in part, the result of the visual preferences of the era in which egg tempera dominated.  It's true that egg tempera has a great capacity for fine, precise linework – but it's also perfectly possible to work in a looser, more painterly style with the medium. I love to see artists work this way as it helps egg tempera to break out if its 15th century shell and expand the medium's range.  

One of the unique characteristics of egg tempera is its capacity for layering; it's possible to accumulate literally scores of distinct layers in a single day (whereas if you applied 100 layers of watercolor or gouache you'd end up with mud, since the underlying layers remain soluble; and if you painted 100 distinct layers of oil it would take you as least as many days).  The only other medium that I can think of that has a similar capacity for layering is acrylic (which, as "plastic" has a different feel from tempera, which feels more "organic", so to speak).  Many, many layers (of local color, glazes, scumbles, whatever) can impart a lot of atmosphere and depth to an image.  So by applying just a few thick layers versus many, many thin ones, you're not taking advantage of a special attribute of the medium - but that's not a disadvantage if you're getting the results you want in just a few layers.

Pure egg tempera has a high PVC – lots of pigment relative to binder. There's so much pigment that pigment particles protrude slightly above the level of the binder, which creates a porous, more open and absorbent surface.  This makes the surface of egg tempera more vulnerable to atmospheric moisture & things landing on and getting embedded into the surface.  Tempera Grassa's surface isn't as vulnerable as pure tempera but a bit more so than oil.  To protect the surface, you can either frame under glass or varnish.  Varnishing is a complicated subject in egg tempera; there are pros and cons, and it takes consideration and experience to do well.  This has been discussed in other threads (search the website for varnishing egg tempera). 

Finally, to clarify – the correct term is egg tempera.  It comes from the idea that pigments are being "tempered" with a binder of egg yolk. Tempura refers to Japanese fried food.  A common mistake but good to clarify. I think that addresses all your questions. 

Koo Schadler

Dear all,

I am working in homemade tempera grassa, oil:yolk=1:1 with various water content added.

I would like to start painting with thicker impasto and then move on to thin glazes and scumbles in subsequent layers. I would want brushstrokes to show through to the end.

Are there any suggestions?​

My ground is half-chalk, but I could move over to traditional gesso if needed.

Kind regards,

Damir P.

I concur with Brian about not going too impasto.  I've played a bit with how thickly I can apply both egg tempera and tempera grassa, and depending on various factors (water content in paint, pigment, thickness, percentage of yolk:oil in tempera grassa) cracks can develop - sometimes visiible to the naked eye; but I've also looked under a magnifying lens and raking light, and perceived hairline cracks in thickly applied paint.  So initially, as you're developing a feeling for how far you can push it, you may want to use a lens and strong light to check for fine cracks in your impasto paint. 

My understanding is that the main reason thick passage of tempera crack is that water comprises a large volume of wet tempera paint; hence much of a thick blob of tempera paint disappears quickly (via evaporation of water) and, consequently, a thick egg tempera paint film doesn't have time to coalesce into a stable network.  The result is cracking.   Is this about right, Brian?

One way I've been able to apply slightly thicker areas of tempera without getting cracking is to let a small pile of properly tempered paint sit for a bit. I occasionally mist it, but only very lightly - I don’t fully rehydrate it.  Gradually the paint loses its water content and eventually, over the course of a few hours, reaches a consistency that is akin to softened butter (or, for that matter, oil paint).  I can apply this thicker quality tempera paint with some degree of impasto.  Because it's lost water content gradually (over the course of a painting day) it seems to tolerate being somewhat thick and doesn’t crack.  Granted, it is not the 1/4” dab of paint that can be achieved with oils.  Still, it is genuinely thick for egg tempera (perhaps 1/16” or so) and appears very dense and opaque relative to the more characteristically thin layers that surround it.  You may want to play with this idea with tempera grassa as well - though I'd be interested to hear what Brian thinks of this practice, and if there are any potential pitfalls. 

Koo Schadler 

Hello, Joyce - always a pleasure to hear tales of Wyeth and his methods. I'm curious, do you know how long the painting of Dyad cured before he re-painted on top of it?  

My experience is that after about 2-3 weeks of a tempera painting sitting (no new layers applied), the surface gradually, increasingly resists fresh layers of paint (paint beads up or slips when applied). The longer a painting sits and polymerizes, the more resistant the surface becomes.  I used to think this meant one couldn't build on top of a cured tempera painting - but then Ross Merrill (one time director of conservation at the National Gallery, for those not familiar with the name) told me it was okay to paint upon a cured tempera surface.  I also spoke to Robert Vickrey on this subject.  We were in a show together, Vickrey was quite old at that point and he was taking old, unfinished paintings out of storage to rework them.  I asked if he'd experienced any problems accumulating fresh layers of paint on older work and he emphatically told me, no problems at all.  

Just because it's possible to layer paint atop an older painting doesn't, of course, necessarily mean long term adhesion between the old and new layers.  Yet I often hear from tempera painters who want to rework older pieces - so to address this I advise: 1. Make sure the painting's surface is clean (no dust, grease, etc. that could compromise adhesion); 2. Lightly open up and abrade the surface with a 600 or higher grit sanding sponge, to give fresh paint something to latch onto (this step is critical); 3. If necessary, apply a very thin "nourishing layer" (as the icon painters refer to it), i.e. 1 part egg yolk to 8 parts water or so. The last step is not preferred, since it could lead to excess lipids in the paint layers and subsequent efflorescence – but it does make a polymerized paint surface more receptive to fresh paint.

I'm not a fan of using the whole egg – as you note, Joyce, the white, which is primarily albumen, is brittle and doesn't, as far as I know, contribute positively to the paint film. 

As to how much impasto either pure egg tempera or an egg + oil emulsion is capable of – it's important to note, in our ongoing discussion, that "impasto" is a vague term.  I do think tempera can be applied somewhat thickly – with a consistency of perhaps light cream – and this can appear as "impasto" relative to egg tempera.  I don't think it can come anywhere close to the literal three-dimensional blobs that pure oil and acrylic can achieve. 

Koo

​Oh, and thank you for your comments on my work, Joyce.  Much appreciated.  I try to make my temperas as carefully as I can, thanks in part to the help I get on MITRA. 

Koo, your insights are very helpfull as always.

It seems we had similar practise, although different regarding impasto topic.

I mix marble dust and egg yolk without add of water and then apply them with paint knife. This way I do not need to wait for water to evaporate. Once they are on ground I use bristle brush to make hair imprint on. There is one more thing I do. I used coarse marble dust (150-300 microns) so impasto is pronounced without too much pigment and binder, in quantitative meaning. 

The potential problem is the fact that this ''impasto'' layer contains coarser particles then ground. Hovewer, layer is applyed localy and overpainted. I see no cracks or delamination.

Any thoughts?

Damir P.

Thanks for this topics. I get some important things from here.