About Silver Point
"Metal point, descendant of the stylus of classical times and ancestor of the modern pencil, a small, sharpened metal rod used for drawing precise compositions on paper or parchment. The metal could be lead, silver, copper, or gold, but silverpoint was the most common choice because it is the most suited to permanent drawing, its stroke adhering unerasably. The silverpoint was of great value in producing the hard, clearly defined line required, for instance, by miniaturists; modelling, emphasis, and light phenomena, however, had to be rendered either by means of repetitions, dense hatching, or blanks or else supplemented by other mediums." — Encyclopaedia Britannica (online), 1996.
"Silver has long been the preferred metalpoint medium, due to the ease with which it slides over a prepared surface and responds to pressure and for its trait of tarnishing over time. The color of the silver is gray when it is first applied to a prepared surface. Upon tarnishing, the silver attains a warm, mellow, brown tonality. The degree and rate of transformation is dependent on exposure to air, pollution, and the chosen ground. Artists who have worked in the medium often greet the resulting change in color with a sense of excitement and surprise, a process categorized by Victor Koulbak as the 'self-developing of the drawing.' The silver radiates a soft, effusive tonality, an almost ghostly luminosity. Silver acquires a shimmer and, as a result, it catches and reflects light." — Bruce Weber, "Silverpoint Drawing," in American Artist, March 1986.