mezzotint, a "ground" has first to be laid, and all the quality of the plate depends upon the manner in which this is done and the scrupulous care with which the copper plate has been previously polished.
In France, the original home of aquatint, a "dust" ground is laid, but in England a "spirit" ground is the most usual method. In the former a specially constructed box is set in motion after being partly filled with finely-powdered resin. Into this chamber charged with resin dust the copper plate is placed so that an even deposit may fall upon its surface. On the withdrawal of the plate it is heated so that the particles of dust adhere to its face. It is then ready for the next stage.
In England the same result is obtained by covering the copper plate with a solution of resin dissolved in spirits of wine. In evaporation the liquid leaves the resin spread evenly on the plate in granular form. This, then, is the process of laying the ground for aquatint. The success of the plate depends upon the minute grains of resin being of the same size. But the difficulties attendant upon this first process are not easily overcome, in cold weather the resin will not granulate, and it is equally obstinate in very hot weather. Dampness in the air is again a factor in producing erratic results, so that it will readily be seen that this first operation of aquatint becomes a highly skilled operation in which the resources of science have to be employed.
The margin of the plate is varnished or "stopped out," and it is usual to leave a small strip at the side
