THE READER is referred to Chapter XI for a complete statement of Rubens' formulas, techniques and principles. It is believed that only by reading through this chapter from beginning to end will the artist be able to derive full practical benefit. The present summary may then be useful..
In choosing the supports for his grounds, Rubens made a distinction between those that were to be used for pictures of small dimension, to be executed by his own hand, usually alla prima, and those that were destined for the large, long drawn out works in which his pupils assisted. For those in the first category, he generally used panels of hard wood--oak or walnut. Their preparation is described in the chapter on grounds on Page 189. When the last layer of the priming of these panels was dry, it would be colored with a light brownish tone, diluted with the jelly medium (described later) so as to be almost a glaze. He painted over this surface only after it was thoroughly dry. The use of the medium in the toning of his panels accounts for the streaky effect that can be seen on the grounds under the painting..
For the larger, more important paintings, he seems to have preferred a final coat of priming, tinted gray (black mixed with white). This also was not painted on until it was thoroughly dry..
Rubens' palette was essentially the same as the Italians. The colors were ground with a generous amount of black oil (see Page 16o). The white only was ground with raw oil. To each of the colors, after they were ground, including the white, was added a quantity of beeswax (dissolved in oil) in the Proportion of about one third of the volume of the paint. The actual quantity would depend upon the kind of picture to be painted. Its function was simply to strengthen the impastos and to reduce the glossiness of the surface, when such an effect was desired..
The jelly medium (see Chapter XI) was made by mixing approximately a little more than a spoonful of the black oil