5 INPAINTING IN LAYERS TO PRESERVE QUALITY

There are three attributes essential to quality which have to be imitated by the restorer, and they are all achieved by building up inpainting in layers. They are:

1. Luminosity, the phenomenon which makes some surfaces reflect light in such a way that they appear to be lit from within. The most striking example of this is human skin. Painters of all ages have struggled to imitate it in paint, and older painters often succeeded by using a brilliantly light ground under a layer of complete undermodelling, with final color glazes.
2. Cool transitions, which the older painters usually achieved by applying a translucent light paint over dark paint, make the light paint appear much cooler than it really is. This is called the ‘turbid medium effect.’ A thin layer of the warm medium tone would be applied over the edges of the warm shadow, and so automatically provide the cool transitions which enhance quality, as shown in Plate 2.
3. Texture, which is characteristic of each painting, depends on the way the brushstrokes are applied and the viscosity of each paint layer.

It follows that to preserve the quality of the painting, the restorer has to build up his inpainting in the same layers as the painter used, ground, underpaint and design layer, and imitate the original paint not only in color but also in texture and luminosity as closely as possible.

As a matter of fact, though this seems like a cumbersome process, it actually saves time, because it makes invisible inpainting so much easier to achieve. Color matching ceases to be a problem because one design layer color applied thinly or thickly over the correct underlayers will match the original paint over a surprisingly large area. This is a consequence of the fact that the painter got his color variations in just that way.