orate the soot with the ground by heating the plate slightly. This
gives a black ground, against which the lines appear light, the
negative of the ultimate print. The black ground is favored, both out of
long-established tradition and because it is very easy to apply.
Furthermore, artists today explain that they also enjoy the feeling of
working slightly blind, that one of their greatest rewards is the sense
of surprise in peeling the first proof print off the plate. For whatever
reason, the black ground has been preferred by the great majority of
artists, both past and present.

The description of Rembrandt's ground in 1660 takes knowledge of the
white ground for granted. Its technique certainly appears to have been
generally well known among artists in the middle of the 17th century.
Rubens, in a letter as early as 1622, mentions having received a recipe
for a white ground, although he could not remember it.[22] The first
technical explanation of the process appeared in Bosse's pioneer
treatise in 1645.[23] There is no reason why Rembrandt should not have
known of the white-ground technique and every reason to suppose that he
did.

There is one piece of strong evidence that he did use a white ground
about 1631. One of Rembrandt's drawings exists which, unlike most of his
sketches is an exact prototype (in reverse) of a specific etching,
_Diana at the Bath_.[24] The back of this drawing is covered with black
chalk, and its lines show the indentation of tracing. The only
reasonable explanation of this evidence is that Rembrandt placed his
prepared drawing on top of a white-grounded plate and traced the lines,
depositing the black chalk lines on the ground, where he could then
trace them with his etching needle. Another similarly indented
drawing--for the portrait of Cornelis Claesz Anslo--has been held to
show the same procedure as late as 1641. This drawing, however, is
backed, not with black chalk as previously cited, but with ocher
tempera.[25] Although surely used for tracing, this gives perhaps even
more evidence of his use of a black ground rather than white, although
ocher lines would show on either. These conclusions are not meant to
imply in any way that Rembrandt used the tracing of a drawing for his
_Landscape with a hay barn_.... There is every probability that he did
not do so. The implication is rather that only where a traced drawing
with black backing exists do we have circumstantial evidence for the
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