Silverpoint is a drawing technique with roots that go back to the time of the Renaissance.  The technique involves drawing on prepared paper with a small wire of silver sharpened to a point, much like a hard graphite pencil. As the stylus is dragged across the paper it leaves a mark of silver.  The layering of these hatched and crosshatched silver lines build up to create a soft value study. The technique is unique in that over time the drawing changes and becomes luminous as the silver tarnishes. 
         Leonardo Study of the Head of a Girl, 1483, silverpoint on brown prepared paper
Leonardo, Raphael and Durer are all Renaissance masters who experimented with silverpoint.  Durer’s father was a metal smith and likely introduced his young son to this technique. Silverpoint is a delicate, but somewhat unforgiving medium; but with some practice the results can be remarkable.  
Silverpoint Drawing, History and Technique
                   Leonardo, Horse Studies, 1493, silverpoint on blue prepared paper
Contemporary artists using silverpoint begin the process, much as the Renaissance masters did, by preparing their paper with a ground.  The ground can be anything from house paint to commercially prepared grounds such as Golden’s Artists Supply“Silverpoint/ Drawing Ground”.  Watercolor can be added to the ground to create a toned surface. Using a rag paper the ground is applied with a brush and allowed to dry for at least 24 hours.
According to artist/author Juliette Aristides Lord Frederic Leighton worked on this rather large (21 x 15.5 inches) silverpoint drawing “from morning to evening for a full week”.  
Silverpoint Drawing, History and Technique
 Lord Frederic Leighton, Study of a Lemon Tree, 1858, silverpoint on white prepared paper
Silverpoint Drawing, History and Technique
             Marie Dauenheimer, Portrait Study, 2010, silverpoint on white prepared paper
Silverpoint Drawing, History and Technique
           Marie Dauenheimer, Figure Study, 2012, silverpoint on white prepared paper
Silverpoint Drawing, History and Technique
             Marie Dauenheimer, Figure Study, 2012, silverpoint on white prepared paper
If you are interested in learning more about how to prepare paper for silverpoint and about this technique watch this instructional video from Golden (scroll down).
I highly recommend this technique!  It is enjoyable and the results can be brilliant!