r that has been wetted with a sponge. One sheet of wet paper to
two of blotting-paper will be enough. The pile of blotting-paper and
wet paper is put in the press and left for an hour or two under
pressure, then taken out and the common paper removed.

The blotting-paper should now be slightly and evenly damp. To flatten
the vellum the open pairs of leaves are interleaved with the slightly
damp blotting-paper, and are left for an hour under the weight of a
pressing-board. After this time the vellum will have become quite
soft, and can with care be flattened out and lightly pressed between
the blotting-paper, and left for a night. The next day the vellum
leaves should be looked at to see that they lie quite flat, and the
blotting-paper changed for some that is dry. The vellum must remain
under pressure until it is quite dry, or it will cockle up worse than
ever when exposed to the air. The blotting-paper should be changed
every day or two. The length of time that vellum leaves take to dry
will vary with the state of the atmosphere, and the thickness of the
vellum, from one to six weeks.

Almost any manuscript or printed book on vellum can be successfully
flattened in this way; miniatures should have pieces of waxed paper
laid over them to prevent the chance of any of the fibres of the
blotting-paper sticking. The pressure must not be great; only enough
is needed to keep the vellum flat as it dries.

This process of flattening, although so simple, requires the utmost
care. If the blotting-paper is used too damp, a manuscript may be
ruined; and if not damp enough, the pressing will have no effect.

CHAPTER IV

Sizing--Washing--Mending

SIZING

The paper in old books is sometimes soft and woolly. This is generally
because the size has perished, and such paper can often be made
perfectly sound by resizing.

[Illustration: FIG. 17.]

For size, an ounce of isinglass or good gelatine is dissolved in a
quart of water. This should make a clear solution when gently warmed,
and should be used at about a temperature of 120 deg. F. Care must be
taken not to heat too quickly, or the solution may burn and turn
brown. If the size is not quite clear, it should be strained through
fine muslin or linen before being used. When it is ready it should be
poured into an open pan (fig. 17), so arranged that it can be kept
warm by a gas fla