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arbrador 14-07-17 02:36 AM

Using Base Coat to speed up tempera layers
Hi All~

Just finished reading Koo's book cover to cover. I found it riveting like a good novel...more like The Odyssey.

My question is when applying a "base coat" of thicker cream like consistency, especially a color of darker value, would it not negate the luminous quality of the white gesso? Of course one would continue to build layers adding white to most colors so luminosity would still be achieved by glazing and scumbling. But I am confused as to the potential drawbacks of obliterating the white gesso especially with darker valued colors.

Thanks for any insights on this.

Lora Arbrador

Koo Schadler 15-07-17 04:58 PM

Hello Lora,

Many thanks for your enthusiastic review of my book - I'm very appreciative...but also a bit embarrassed. It is a self published effort with limitations, and only a genuine egg tempera nerd (i.e. you or me) could find it riveting. I'm very glad you find it useful...but please, generous as you've been, no more thoughts on the book for now.

....well, except to ask excellent questions elicited by it, such as the one you posed. As I've mentioned in other posts, I believe there is something of an egg tempera "mythology" that creates misconceptions about the medium. The creed that one must maintain the luminosity of the white gesso ground belies the complexity of luminosity specifically and painting generally. Please bear with a long post in an effort to explain this.

What does luminosity mean? I've asked many painters, and most respond that it is when a painting conveys light, brilliance, illumination. There are different ways to achieve this. I believe two of the most important are,

(1) depict subject matter as if illuminated by a light source (this sounds obvious, but I see many students begin a painting without knowing what the light source is or where it's coming from, and not being consistent with the effects of the light source on subject matter); and,

(2) have a good value arrangement within the overall design of a painting that includes all three values: lights, middles and darks (because lights appear more luminous in contrast to dark; imagine how a flashlight appears when it shines in a darkened versus a lit room).

These two methods (light source and value contrast) imply or suggest luminosity and, in my experience (looking at the history of art) are top priorities in creating a luminous image. (Think of that most luminous of painters, Rembrandt! To be clear, he painted in oil, not ET - but it's his use of light and values as much as the paint that make his images shine).

There is a third way to convey luminosity in painting which I call literal luminosity (versus implied, as in the two methods described above). It is to glaze: Apply transparent color on top of a white, reflective surface. Light travels through the see-through color to the opaque white layer beneath, bounces off that opacity, travels back up through the transparent color, and, voila, luminosity is achieved!

The misconceptions about this third method for creating luminosity are,

(a) that a glazed effect must happen everywhere in a painting (in fact, it can happen selectively), and

(b) that the white, reflective surface must always be given by the true gesso ground (it can also come from intermediate paint layers).

So, to explain the above in more depth...

I know it can feel anathema to some tempera artists to "cover" the white gesso, but how can a true dark value be rendered if the white of the gesso is showing through it? To render a full range of values, dark is requisite (and by dark I mean a number 0 to 2 or 3 value on a 0 to 10 step value scale, with 0 = black and 10 = white). So to establish darks in tempera the white gesso ground actually must be fully covered. (This is one of the purposes served by the dark ink underdrawing characteristic of the Italian Renaissance working method; among other things, it established the dark values.)

Can a local dark paint (such as black), if it fully covers the gesso, still appear "luminous" within a painting? A thin, transparent glaze of pure color could be applied over a black, to modify it's temperature and add a bit of chroma, but I don't think black can really be called luminous in and of itself (it might be rich, deep, intense - but probably not "full of light"). However it can serve to create luminosity; for example, a rich black background will enhance the "brightness" of a high value, high chroma lemon illuminated by a single light source. In that instance, the black background participates in the luminosity of the lemon, even if the black itself isn't necessarily luminous. Not every part of a painting need be inherently luminous to create (or contribute toward) a luminous image; in fact, paradoxically, a lack of brilliance in some areas can enhance brilliance elsewhere.

Onto misconception (b): Reflectivity must always be given by the gesso ground. Painting is a series of endless choices and decisions; among them, what quality of the paint do you want to convey? If one paints very thinly, as with watercolor, that creates one sort of effect. Or, one can work with a more "bodied" paint, such as oil, and create a different effect. Egg tempera has the possibility of going in either direction. If painted thinly (more in the watercolor camp) the white of the gesso continues to shine through and can contribute to luminosity (although remember, there are other, equally important factors to consider to create luminosity).

But what if an artist (myself among them) prefers a more bodied paint; one that conveys more solidity and atmospheric depth? The only way to achieve that is to work with a thicker, more bodied paint. Egg tempera (unlike watercolor) can be applied more thickly (although not nearly as thick as oil - ET has its limits in this regard). ET also can be applied in many layers to build up depth and body (one of egg tempera's strength is it's nearly endless capacity for layering relatively quickly). Adding some percentage of white to certain areas or layers of a painting is also critical to creating body and opacity. If an ET painter chooses to build up a dense, bodied painting in these three ways (have some layers of thick [relative to ET] paint; accumulate many many layers; add some percentage of white pigment to some layers) at some point the gesso ground disappears.

Does this mean there's no luminosity? No; luminosity can still be achieved through methods 1 and 2 (lights source and value relationships); and glazes still can be applied atop a bodied paint, just as oil painters do. After all, you don't hear oil painters worrying about losing the white of the ground (in fact, they often tone their grounds. More on that below...). It's true that oil paint has much more body and covering power, can be applied more densely; and that egg tempera is more prone to behaving transparently because it's a thin paint compared to oil. Nonetheless, with enough opaque layers of enough thickness, tempera covers the gesso...but then that bodied, opaque paint itself (as in oil) becomes the base upon which luminous glazes can be applied.

There is also (as you point out in your question) the possibility at any point in the layering of an egg tempera painting of applying a thin, transparent layer of white - i.e. a scumble - over the surface, and then glazing upon that; the scumble provides the white, reflective function that the gesso ground does. As you know, I do this many, many times in a painting.

One more point: another important contributor to a feeling of "light" or illumination in a painting is to create dense, rich, opacity in highlights - think of the impasto blobs Rembrandt created. In this example covering the white of the gesso (via impasto highlights) doesn't decrease luminosity, it actually contributes to a luminous effect. Really, there are so many options, so many ways to layer the paint to affect values, chroma, temperature, opacity, transparency - I'm just scratching the surface here!

I don't mean to say that a gleaming white gesso ground is irrelevant, even to a painter who, like me, covers it with a bodied paint. As oil and egg tempera paints age they become more transparent. Whatever the original ground, it's effects on the painting become more consequential over time. Paintings on white grounds are more likely to retain their original colors and light values; paintings on dark grounds (like some oils done on umber toned grounds) lose their light values. One could also consider the converse; that paintings on pure white grounds, as they age and become more transparent, lose their dark values... but I haven't seen studies to show this to be a concern. What I more often see is recommendations from conservators that working on a white ground helps a painting's values stay consistent as the painting ages.

So, to conclude this sermon....there is nothing wrong with "preserving" the white of the gesso as one paints; it's one perfectly viable way to work in ET and creates one sort of effect. There is also nothing wrong with covering the gesso with many layers of paint; doing so does not mean you've lost the chance to create luminosity. The challenge is figuring out what kind of painter one wants to be. Sometimes one knows intuitively, automatically. I also see painters who can't decide what sort of "look" they want to create - so many options, which do I choose?! This is one of the benefits of a medium having a "mythology" - it limits the paint's possibilities, so there are fewer decisions to make. But on the downside, it limits the paint's (and painter's) possibilities.

Hope that helps. You know where to find me if you have more questions. Thanks again for your interest and support, which give encouragement and camaraderie to the lovely, challenging solitude of the studio.


arbrador 22-07-17 04:39 AM

Hi Again Koo,

Thanks so much for your generous and detailed response. Having just read the book cover to cover I did read much of what you wrote in your response to my question in the the various sections of the book.

But still somehow I came away with my own misconception of clinging to the orthodoxy of the traditional gesso ground supplying an almost magical luminosity to ET painting. On page 143 in the Luminosity Chapter under subheading PUTTING IT ALL TOGETHER paragraph two, you say, "Egg tempera is often considered an especially luminous medium" and then explain why. And on page 134 misconception #9 you say something similar with the misconception being that ET is the most luminous medium.

I feel humbled and straightened out on this point but will continue to idealize ET as a magical medium! It just feels that way to me!

I'll be especially attentive in my current painting to all that I've learned in reading the book and see if can understand more in an experiential way.

Thanks again and wishing you a satisfying summer of painting,


Koo Schadler 22-07-17 07:33 PM

Hello Lora,

Egg tempera IS a very magical medium - no doubt!

And it is a medium that can (tho' not inevitability) appear very luminous....but so can other mediums. I specifically mentioned Rembrandt in my previous answer because he worked in oil, not ET, yet is often considered the most luminous painter in the history of western art - and no wonder; if one looks at the specific the ways in which luminosity is created it's apparent that Rembrandt did every one of those things.

I think to make the most of painting it's helpful to differentiate between what a painting medium can and cannot do, versus what the formal, visual language can and cannot do; while there is some overlap between the two subjects, the possibilities and considerations of each are distinct, to a large extent.

Anyhow, I don't mean to minimize the wonder of ET - I feel it too.


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