June 2023
Self-Portrait in a Cap and Scarf with the Face Dark, Rembrandt, 1633, National Gallery of Slovenia, Ljubljana, Slovenia (A. Kraš) In the context of metal etching, corrosion assumes a deliberate and controlled role. Etching selectively removes the surface of a material using corrosive substances. By protecting the desired parts of the surface from corrosion, only the unprotected areas are removed to create specific patterns. It finds applications in art, printing, and industry. Rembrandt van Rijn, the legendary Dutch painter, printmaker and draughtsman, employed this technique with extraordinary finesse. While the tools, materials, and techniques have expanded significantly since Rembrandt's time, the fundamental principles of etching in art remained the same. Rembrandt's etching begins with coating the metal plate (usually copper) with an acid-resistant substance called the "ground." During Rembrandt's time, the ground was made from powdered bone ash or charcoal and linseed oil The ground acts as a barrier, preventing the acid from affecting areas that should remain untouched. Once the ground is applied, Rembrandt used a needle-like tool called an "etching needle" or a brush to meticulously scratch through the ground, exposing the underlying metal. Subsequently, the metal was immersed in an acid bath typically made of nitric acid, which selectively corroded, i.e. dissolvde the exposed metal. The duration of immersion determined the depth of corrosion and the intensity of the resulting etched lines or textures. This process required precision and control, as Rembrandt had to etch each line with varying pressure to achieve a range of light and shadow effects. After the ground was cleaned, the plate was positioned on the bed of a rolling printing press and covered with a sheet of paper onto which the etching pattern was finally printed. In addition to the ability to produce multiple prints from a single metal plate, existing etchings could be modified by grinding specific parts of the plates and reetching, allowing for changes in the prints. In his self-portrait shown in the picture, Rembrandt's deft etching skills can be observed through the intricate lines that delicately define his face and the folds of his clothing. |