rtainly not over
the "Encre de Chine Liquide." Should the student have occasion
to draw over salt-prints he will find it wise to use waterproof
ink, as the bleaching acid which is used to fade the photographic
image may otherwise cause the ink to run.

[Side note: _Papers_]

Bristol-board is probably the most popular of all surfaces for
pen drawing. It is certainly that most approved by the process
engraver, whose point of view in such a matter, though a purely
mechanical one, is worthy of consideration. It has a perfectly
smooth surface, somewhat difficult to erase from with rubber, and
which had better be scratched with a knife when any considerable
erasure is necessary. As the cheap boards are merely a padding
veneered on either side with a thin coating of smooth paper, little
scraping is required to develop a fuzzy surface upon which it is
impossible to work. Only the best board, such as Reynolds', therefore,
should be used. Bristol-board can be procured in sheets of various
thicknesses as well as in blocks.

Whatman's "hot-pressed" paper affords another excellent surface
and possesses some advantages over the Bristol-board. It comes
in sheets of various sizes, which may be either tacked down on
a board or else "stretched." Tacking will be satisfactory enough
if the drawing is small and is to be completed in a few hours;
otherwise the paper is sure to "hump up," especially if the weather
be damp. The process of stretching is as follows: Fold up the edges
of the sheet all around, forming a margin about an inch wide. After
moistening the paper thoroughly with a damp sponge, cover the under
side of this turned-up margin with photographic paste or strong
mucilage. During this operation the sheet will have softened and
"humped up," and will admit of stretching. Now turn down the adhesive
margin and press it firmly with the fingers, stretching the paper
gently at the same time. As this essential part of the process must
be performed quickly, an assistant is requisite when the sheet
is large. Care should be taken that the paper is not strained too
much, as it is then likely to burst when it again contracts.

Although generally employed for watercolor drawing, Whatman's
"cold-pressed" paper has some advantages as a pen surface. Slightly
roughish in texture, it gives an interesting broken line, which
is at times desirable.

A peculiar paper which has considerable vogue, especially in France
and England, is what is kn