Black Velvet

From Draw Like Da Vinci: Drapery: How one ought not to give drapery a confusion of many folds, but only make them where it is held by the hands or arms, and the rest may be suffered to fall simply where its nature draws it; and do not let the contour of the figure be broken by too many lines or interrupted folds. 

Drawing shadows in drapery requires dense filled-in shading. This is the opposite to the general rule of keeping shading lighter than contour lines. Whichever medium you use – charcoal, pencil, chalk or ink – the deep folds of drapery require dense shading in their concavities. Da Vinci fills in solid areas with wash, sometimes reinforcing it with hatching lines. In his brush drawing Drapery study for the Virgin of the Rocks, he uses line hatching with white gouache as he did over the horseman in the storm.

Ref. Leonardo da Vinci (1452–1519). Hurrican over Horsemen and Trees (aka A tempest). c. 1518, Pen and ink over black chalk with touches of wash and traces of white, and brush line hatching with white gouache on the horsemen, on grey washed paper, 27 x 40.8 cm. Royal Collection Trust, London (RCIN 912376).