Mix the ground color of Venetian red with a little vermilion and white, until it is of the tint required. The first layer of spots is produced by sprinkling in the following manner: Mix some of the ground color with a larger quantity of white, in a paint-pot, and use a large brush which has been well worked in the color; hold the palette knife over the paint-pot and press the hairs of the brush against the edge so that as much as possible of the color may be forced out of it; then, taking the handle of the brush between the palms of the hands, roll it to and fro with a rapid motion, the ends of the hairs being below the level of the paint.
Now hold a stick firmly in front of the work and strike the handle of the brush against it; the color that still remains in it will thus fall on the surface in a variety of small dots. Great care on the part of the painter is necessary at this stage, so as to distribute the spots equally; otherwise, whilst one part of the work will be left only partially spotted, others may be so thickly covered that the drops will become confluent and not be visible as spots afterwards.
When this work has become sufficiently dry, the sprinkling may be repeated by dipping the brush into a color rather deeper than the ground; it may be Indian red, with sufficient white to give it a body. The sprinkling with this color must be done very sparingly and rather more in some parts than others.
The last sprinkling is to be done with a clean small tool dipped in white paint only and the spots are to be very fine; as much color, therefore, as possible should previously be removed from the brush, and it will be found that, when so little color remains in the brush that it will scarcely mark a board when rubbed on it, there will still be enough to produce the fine dots when struck against the stick. The stick should be held at some distance from the work, as the farther away the finer will be the dots. In imitating some specimens, the three layers of spots are laid on and, in addition, a narrow opaque white vein is to be run amongst the spots; from this transparent threads are drawn in various directions; these cannot be added until the whole of the sprinkling is quite dry and hard; they must then be formed with a sable pencil and the threads drawn out with a feather.