In good sacred art, even the appearance of the negative space around the figure is controlled by the artist The iconographic tradition portrays the heavenly realm, which is outside time and crucially (in this context) space. In order to convey a sense of the heavenly order in an earthly image, all sense of depth beyond the plane of the painting is deliberately eliminated. There is no superfluous background in an icon and the negative space around a figure is meant to appear flat. The naturalistic tradition, in contrast, seeks to do precisely the opposite. It is portraying Historical man, that is man after the Fall but not yet redeemed. This is the world of time and space that we live in. When painting in this tradition, the artist deliberately sets out, therefore, to create the illusion of space. There are a number of ways that an artist can do this. One way is to draw a scene with conventional perspective (and the icon painter can do the converse by using inverse perspective). However, in order to use either form of perspective, there must be a background scene painted in the area around the main figures onto which the artist would apply it. If there is not background scene the artists must use other means to control our sense of how the negative space appears: as either a three-dimensional space or a flat surround in the plane of the painting.
One is the choice of medium or media used in the painting. One option is to gild, which always looks flat. (You can see this 12th century Greek icon Moses at the burning bush, above.) If the background is painted rather than gilded, then egg tempera, fresco and mosaic always tend to look flat too, whereas oil paint, especially when used for painting shadow, always creates a strong sense of space beyond the plane of the painting.
Just to illustrate, compare the two paintings first and second below: and icon of Our Lady and Our Lord painted by Gregory Kroug in the 20th century; and Bellini’s Sacred Conversation painted in 1490. Neither has scenery painted around the figure, yet first has a white background that is designed to eliminate, as far as possible any sense of space beyond the plane of the painting. Bellini on the other hand, has painted a dark background that plunges into the depths, and gives a sense of almost infinite space – there is a gaping chasm beyond the figures.
The next painting (below, left) painted just 4 years before Bellini's by Carlo Crivelli in 1486 demonstrates why the standard choice of medium became oil rather than egg tempera. In this painting of the Annunciation, Crivelli uses single point perspective in order to create a sense that the pathway on the left is receding into the deep distance. The draughtsmanship is fine, but for me the painting just doesn't work. I have seen the original many times in the National Gallery in London and every time I see it what strikes me is that although the size those tiny figures in the background and all the perspective lines pointing to them tell me that they are in the distance, they just don't look distant. They look small. The reason, I feel, is the medium that Crivelli is using is egg tempera.
Even beyond the choice of medium, there are ways of manipulating the paint also that it can enhance or reduce the natural look of the paint in this respect. These are ‘glazes’ and ‘scumbles’. I do not know for certain, but as far as one can tell from the reproductions, my guess is that this is what Kroug and Bellini were using. Certainly, if I was trying to create the same effect, this is what I would do.
Glazes and scumbles are created when a translucent layer of paint is painted over another. When the tone of the upper layer is darker than that of the lower, it is called a glaze; when the tone of the upper layer is lighter than the lower layer it is called a scumble. If I were seeking to create the Bellini effect I would use a glaze in the background; and if seeking to create the Kroug effect, I would use a scumble.
When light hits the surface of the painting, some light and some is transmitted through to the next layer of paint deeper into the painting, and some is absorbed and re-emitted back outwards. This re-emitted light bears the character of the layer that absorbed it. It is why, for example, when you shine blue light on paint, that it appears blue. Consider now the light that was not absorbed, but which passed through the layer of paint. It is then incident upon the layer of paint underneath. At this interface the same thing happens again: some is transmitted and some absorbed and re-emitted. This goes on right until some of the light penetrates all the way through to the ground. If the ground of the painting is white and so very reflective, good part of the incident light comes back out of the painting.
When we look at a painting, what the eye sees is the aggregate of different rays of light emerging from differing points within the paint layer and bearing the mark of the layer that last absorbed and re-emitted it. When I paint with tempera, which can be diluted into thin washes of paint, the final effect is the cumulated effect of as many as 15 layers of paint of varying tones and colours. If you shine a light directly onto the painting then the optical effect is that the painting is itself a source of light. It is especially beautiful if the light is a flickering candle.
If you use a glaze with tempera, the usual medium for icons, it creates richer, jewel like surface. I you apply one in oil, the effect is even more dramatic. It causes the surface to appear to sink into the deep distance. The shadows of baroque art, such as we see in a Rembrandts, seem to sink into the infinite. This is effect, is created by a glazes and it is perfect for the numinous, mysterious feel that baroque artists sought. The painting right is Rembrandt's St Bartholomew.
A scumble, on the other hand creates the opposite effect. The upper layer appears to float on the surface. Generally, it is less often useful to an artist and so you don’t hear the term used very often by artists. However, it is extremely useful to any icon painters wishing to create this Kroug effect. You simply ensure that the final layer of paint is the lightest in tone. If the layers underneath are a combination of glazes and scumbles it still looks interesting and varied, but it thrust forward, rather than sinking back into the painting. What I find so lovely about Kroug’s works is the huge variety of washes of tone and colour that he applies underneath the upper layer, be it glaze or scumble.
So many modern attempts at icon painting that you see don’t do this. The colours are flat, dull and lifeless because they are created by the painting of a number of thick layers of the same paint. Like do-it-yourself decorator painting a wall.
(The painting below is The Virgin at Prayer by the Italian artist Sassoferrato. This baroque artist is using oil to create sinking depths in the negative space around the Virgin. What a wonderful painting! This is in the National Gallery too, and every time I visit, I make a point of going to look at it.)