Though technically part of the intaglio printmaking family, mezzotint might better be described as a tonal method, one in which half-tones were created without using line-based techniques. In many ways it was the exact opposite of line engraving, which required at least small scores to a smooth metal plate in order for anything to print on paper. By contrast, the mezzotint plate, even without the slightest of scores, would produce an entirely black print. This unique effect owed itself to the unusual and interesting preparatory work the plate underwent prior to the transfer of any image. The ‘rocker’, a stubby chisel-like tool with a wooden handle and centimetre-wide curved blade, with serration to its edge, was used to roughen the plate surface, covering it with hundreds, maybe thousands, of tiny incisions. In printing, these miniscule pits retained ink, even after the surface of the plate was wiped clean, producing a velvety black result, quite unlike any other intaglio method.
The mezzotint printmaking method was invented by German engraver, Ludwig von Siegen in the 17th century, though it has often been falsely attributed in the literature to Prince Rupert of the Rhine, who was next to use the process and who reportedly introduced it to England. In fact, the pair initially employed quite different techniques to achieve the mezzotint effect. Von Siegen’s early prints were representative of a ‘Light to dark’ method, whilst the Prince’s, a reverse ‘Dark to light’ method. Von Siegen’s portrait of Amelia Elizabeth, Regent of Hesse Cassel, the earliest dated mezzotint (c1642), was created from a plate, roughened only in select areas, where the darker parts of the illustration were to be. This method could easily be combined with engraving, particularly on parts of the plate not roughened. Prince Rupert’s technique of working from dark to light was much more common and respected, to a greater extent, by masters of the craft. It involved roughening the entire plate surface evenly with a rocker, a tool which he was credited with inventing, then burnishing or flattening out select parts of the plate which would ultimately print much lighter than those not smoothed by the burnishing tool. Areas smoothed completely flat would not hold ink at all and would appear white in the print; other areas would print in mid-tones, between black and white depending on the degree of burnishing.
The exquisite tones and texture achieved by mezzotint made it the perfect medium for the reproduction of paintings, and some in the trade made very successful interpretations of the works of the great portrait painters of the 18th and early 19th centuries. Mezzotint engravers such as Englishmen Samuel Cousins, Valentine Green (engraver to the King in 1773) and Richard Earlom set the benchmark for others. Cousins’ 1831 mezzotint of Lady Grey and Children was truly a masterpiece of tone and texture. With its bright faces and delicate clothing, it was matched only by the finest of hairs and whiskers in his 1884 self-portrait which shows the engraver himself at work. On par with Cousins, the enormously versatile Earlom impressed with all of his mezzotints. He produced several exquisite plates after the Dutch painters and his Flowers and Fruit was simply unrivalled.
For all of its shining detail and misty tone, it’s lamentable that mezzotint was not well suited to the steel plate, for it might have survived longer as a viable printmaking method. A lack of depth, however, of the tiny pits on the soft copper plate meant that few quality impressions could be made before the tone began to degrade as the pressure of the press smoothed them out. By the mid-nineteenth century the mezzotint had all but disappeared; it could no longer compete commercially with line engraving from which a much larger number of editions could be obtained, nor with the developments in lithography, which was fast becoming the print method of choice.
Mezzotint prints began with a copperplate surface, roughened with a rocker. This was a laborious and time consuming process which, according to T. H. Fielding, required the measurement and division of the plate by means of equidistant lines, numerous times, and at cross-angles, in order that the rocking tool could be passed between them, from side to side, until every single part of the plate was covered with a burr. At all times the mezzotint engraver had to take care to apply steady, firm pressure in order than an even burr would appear. Usually, the outline of the illustration was etched into the plate before its surface was roughened, and in some mezzotints these lines can be detected due to the difference in texture to that of the soft mezzotinting. In the case of heavy or overzealous rocking, the engraved lines might be obliterated almost entirely, making it difficult to commence the mezzotint process. For this reason, most image outlines were transferred onto the plate again, after its surface had been roughened, using chalks.
The image transferred, the engraver began the process of introducing light into the plate. Using a scraper, they carefully removed the parts of the roughened surface, essentially smoothing it out again, where the finished print was to be lighter or even white. It was common practice to scrape first from the areas that were intended to be entirely white in the print, and then burnish these sections. The round end of the burnisher flattened out any remaining, minutely protruding burr which, left behind, could introduce unwanted spots or flecks into the final print. Once the highest of lights had been burnished, the engraver began scraping away the next lightest parts, and so on, burnishing as they went, and proceeding gradually from light to dark until all that remained were the deepest shades - in virtually untouched ground.
The method for printing the mezzotint plate was the same for both the ‘light to dark’ and the more common ‘dark to light’ techniques, and both followed the standard intaglio printmaking process. The plate was inked and wiped clean, leaving behind small amounts of ink in the roughened pits below its original surface. A piece of paper was placed on top of the plate and the whole run through the press. The result was a velvety, matt print, rich in texture and simultaneously dramatic and delicate in tone – the perfect combination for a portrait.
Also on display in this cabinet were the following mezzotints:
 Fielding, T. H., The art of engraving, with the various modes of operation, under the following different divisions: etching, soft-ground etching, line engraving…, London, Ackermann & Co., 1841, p. 57.
 Davenport, Cyril, Mezzotints, London, Methuen and Co., p. 54
 Fielding, T. H., The art of engraving, with the various modes of operation, under the following different divisions: etching, soft-ground etching, line engraving…, London, Ackermann & Co., 1841, pp. 58-60.
 Davenport, Cyril, Mezzotints, London, Methuen and Co., p. 13