Focus on The Sleep of Reason Produces Monsters and explore the Technical aspects.
Los Caprichos is notable for its use of aquatint, a printing technique that falls under the category of intaglio printing. Intaglio printing is characterized by the artist applying ink to the grooves of the matrix (i.e., the surface from which a print is made), allowing for intricate lines and refined tonality. According to William M. Ivins Jr., the first official Curator of Prints at the Metropolitan Museum of Art, "every intaglio print in which the lines are laid in a formal manner is an engraving, and every one in which they are laid freely is an etching," thus clarifying that the series Los Caprichos falls under the broad category of "etchings". To produce an aquatint, the image itself is formed by applying a layer of resin (or a substitute of asphalt or bitumen) using one of two technical methods. An artist may allow the resin to settle on the plate as a dry dust by inserting the printing plate at the bottom of a box wherein the dust has been distributed. The printing plate is then heated so that each grain of resin dust melts and adheres to the metal. The alternative method is to dissolve the resin or asphalt in alcohol, and then pour this solution over the printing plate. The alcohol will then evaporate, leaving a thin film of resin which will dry on the plate. The plate is then immersed in acid, which etches the metal in the gaps around the grains of resin. The dust is then cleaned off the plate, to which ink is applied; the ink penetrates the etched depressions, and when the plate is printed, it creates a network of thin etched lines. This process produces a single tone, but the density of the tone varies depending on how finely the dust was ground and how thickly it covered the plate.
aquatint bitumen Metropolitan Museum of Art