This pen and bistre version contains no suggestion of Hell, yet its outline was adapted into one of The Garden's most memorable grotesques.
From the en.wikipedia.org
Pen and bistre on paper.
From the en.wikipedia.org
They could not, however, approach the beautiful, sure clarity with which Rem brandt set down, in a few streaks and slashes of bistre, a windmill facing the estuary from an old bulwark of Amsterdam.
From the time.com
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Bister: a water-soluble brownish-yellow pigment made by boiling wood soot
Bistre (or bister) is both a shade of gray and a shade of brown made from soot, and the general name for a color resembling the pigment. Bistre's appearance is generally of a dark grayish brown, with a yellowish cast.
Is a brown tint made from wood called soot and is used for drawing by art masters of old.