My French Easel: Thick lights over thin darks

Monday, 30 June 2008

Thick lights over thin darks

In oil painting, I have often used thick impasto of light colours while keeping dark areas thin. Turner was a master at using impasto for sparkling light effects

Ostende by Turner

Detail of the same painting showing the light impasto

Lately, I wondered why it makes sense to do this way and why generations of painters have followed this rule. Here is the list of reasons I came with:

Thick applications of paint draw attention: you want the shadow areas to recess, not to stick out (which is literally one of the consequences of an impasto. In her book “Painting better landscapes”, Margaret Kessler explains how thick applications of dark colours can lead to glares and create confusion: “A thickly painted, light door-frame projects forward, jus as thin, darker transparents in the opening itself recede, allowing the eye to enter the depth of the building. Keep in mind that, when your finished painting is hung, the display lights will reflect off any ridges and lumps of paint, creating bright highlights. If you load the opening with dark, thick pain, the lighting will reflect off this surface, pulling the opening forward – thus confusing the viewer.”
Projected shadows: If a light impasto (which means a “thick application of paint”) projects a shadow, then it reinforces the contrast between the light and dark areas. If you place a dark impasto over a light background, the projected shadow will darken the light area and will change the actual size and shape of the shadow area (which becomes the dark impasto plus the projected shadow).
Thick applications of paint can crack as they dry. Reserving impasto technique for smaller areas reduces the risk of cracks. This is exactly what happens if you use impasto in your latest lights.

The incidence of drying time: The white used at the beginning was lead white which had good drying properties (Zinc White and Titanium White were introduced more recently) and allowed thicker applications. Many dark colours take longer to dry and that could be an issue for thick application. For instance, Winsor & Newton classifies Burnt Sienna, Ultramarine Blue, Permanent Alizarin Crimson, Lamp Black and Ivory Black as “medium drying time” and Alizarin Crimson as “slow drying time”.
Impasto is better suited for opaque colours which have a good consistency and a buttery aspect. Many dark colours are transparent or semi-transparent and therefore less effective as impasto. Now, you can find impasto gels that would allow you to get high solid transparent touches.