When the artist proceeded to colour, and had to represent white draperies, he sometimes suffered the ground to remain untouched. Titian did this latterly when he had attained the greatest certainty in practice, and could accomplish much with little labour. The whitish ground was left as a middle tint, the shadows painted in, and the high lights touched on.—[Note KK].
In the process of colouring, the preparation merely washed as it were underneath, was always effective. A drapery, for example, was painted with a transparent colour, the white ground shone through it and gave the colour life, so the parts previously prepared for shadows exhibited the colour subdued, without being mixed or sullied.
This method had many advantages; for the painter had a light ground for the light portions of his work and a dark ground for the shadowed portions. The whole picture was prepared; the artist could work with thin colours in the shadows, and had always an internal light to give value to his tints. In our own time painting in water colours depends on the same principles.
Indeed a light ground is now generally employed in oil-painting, because middle tints are thus found to be more transparent, and are in some degree enlivened by a bright ground; the shadows, again, do not so easily become black.
It was the practice for a time to paint on dark grounds. Tintoret probably introduced them. Titian's best pictures are not painted on a dark ground.