Aquatints usually begin with an etched outline, and have the detail filled in with tiny, sand-like, resin particles layed on in either an alchohol bath or as a powder, before being steeped in the acid bath and then stopped out for the next one. Eight to twelve stages in this process are not uncommon, to achieve the prints wash drawing or watercolour like tonal variations. These images from Vauxhall Gardens aquatinted by James Bluck after a drawing and etching by Thomas Rowlandson and Augustus Pugin published by Ackerman 1 October 1809 show the general sandy effect of the process. This section of the larger image shows how the courseness of the process lends itself to imitate watercolours. Here the enlargement shows the grittyness of the acid bites in the plate lending themselves to the image.
Mezzotints start life black, and the artist then brings in lightness.
First the plate is worked over with a rocker until it is like a file to produce a rich velvetty black. From here the artist then scrapes out the lighter tones of the picture with a scraper and a burnisher for the very white areas of the print. The result is engraving in tone, as true mezzotints have no lines per se, but only areas of relative tonal difference. Mainly portraits were done in this manner, the exceptions being Turner's Liber Studorium , with a mixed etching and mezzotint process. The examples on the left are that of Norham Castle on the River Tweed mezzontinted on steel by Charles Turner after JMW Turner and published 1 January 1824 by Wm.