_The Calotype Process: curling up of Paper._--I am happy in having the
opportunity of replying to your correspondent C. E. F. (Vol. ix., p. 16.),
because, with himself, I have found great annoyance from the curling up of
_some_ specimens of paper. In the papers recently sold as Turner's, I find
this much increased upon his original make, so much so that, until I
resorted to the following mode, I spoiled several sheets intended for
negatives, by staining the back of the paper, and which thereby gave a
difference of intensity when developed after exposure in the camera.
I have provided myself with some very thick extra white blotting-paper
(procured of Sandford). This being thoroughly damped, and placed between
two pieces of slate, remains so for many weeks. If the paper intended to be
used is properly interleaved between this damp blotting-paper, and allowed
to remain there twelve hours at least before it is to be iodized, it will
be found to work most easily. It should be barely as damp as paper which is
intended to be printed on. {41} This arrangement will be found exceedingly
useful for damping evenly cardboard and printed positives when they are
intended to be mounted, so as to ensure their perfect flatness.
It is quite immaterial whether the paper is floated on a solution or
applied with a glass rod. If a very few sheets are to be manipulated upon,
then, for economy, the glass rod is preferable; but if several, the
floating has the advantage, because it ensures the most even application. I
sent you a short paragraph (Vol. ix., p. 32.) showing how we may be
deceived in water-marks upon paper; and when we are supposing ourselves to
be using a paper of a particular date, in fact we are not doing so.
I would also caution your photographic correspondents from being deceived
in the quality of a paper by the exceeding high gloss which is given it by
extra hot-pressing. This is very pleasing to the eye, and would be a great
advantage if the paper were to remain dry; but in the various washings and
soakings which it undergoes in the several processes before the perfect
picture is formed, the artificial surface is entirely removed, and it is
only upon a paper of a natural firm and even make that favourable results
will be procured.