APPLYING THE SILVERING SOLUTION TO THE ALBUMENIZED PAPER.
As each piece of paper takes somewhere about five minutes to sensitize
and hang up to dry, it is evident that the larger the piece of paper
sensitised the greater will be the saving in time in this operation.
Practically a whole sheet of paper, which is about 22 inches by 18, is
the maximum ordinary size, whilst it may be convenient to float a piece
as small as 3-1/4 by 4-1/4. There is not much difficulty in floating
either one or the other if ordinary care be taken, but it is no use
disguising the fact that large sheets are sometimes faultily sensitized
even by experienced hands, if the solution be not in a proper state. The
great enemy to success is the formation of bubbles on the surface of the
solution, and if it be at all contaminated with organic matter they are
more liable to be met with than if the bath be new. It may be taken as a
maxim that no paper should be floated if, to commence with, the bath be
not purified. A flat dish of about 2-1/2 inches in height, and an inch
larger in breadth and length than the paper to be floated, is used, and
the solution poured in to a depth of 1/2 inch. The paper is grasped by
the two hands as shown at page 10, so that a convex albumen surface is
formed downwards, which is placed diagonally across the dish and lowered
on to the surface of the solution; the hands are at the same time
separated outwards, so that the whole surface of the paper is caused
to float on it without any arrest. By this means all air is forced out
before the paper, and no bubbles should be beneath. To make assurance
double sure, the paper is raised from the corners which were not grasped
by the hands, and if by any chance a small bubble should be found, it
is immediately broken by the point of a clean quill pen or glass rod.
Before floating the paper the surface of the solution should be examined
for scum or bubbles, both of which may be removed by passing a strip of
clean blotting-paper across it. The dish employed should be scrupulously
clean, and in cold weather it is a good plan to warm both it and the
solution before the fire previous to use. In warm weather, the albumen
of the paper may be in a very horny condition, which increases the
liability to form bubbles. The writers have found that if the sheet of
paper be exposed to the steam passing from a kettle of boiling water for
a few seconds (moving it so that every portion shall come in contact
with it) just before sensitising, the surface becomes more tractable,
and in a better condition for sensitizing; keeping the paper in a moist
atmosphere effects the same end.
The length of time for floating the paper depends on the subjects to be
printed, _but, as a rule_, three minutes with the 50-grain bath will
be found to answer for the majority of negatives. When the proper time
has elapsed, a corner of the paper is raised from the solution by means
of a glass rod, and grasped by the thumb and forefinger of the right
hand. It is then raised _very slowly_ from off the solution till another
corner is clear, when that is grasped by the forefinger and thumb of the
left hand; and it is finally withdrawn entirely, and drained a minute
from the lowest corner into the dish. It is next hung up to dry by a
corner which should be fastened to an American clip (fig. 7) suspended
from a line stretched across the dark room, taking care to keep the
corner which last left the solution the lowest. A piece of _clean_
blotting-paper about one inch long by 1/2 an inch wide is brought in
contact with this latter corner, and adheres to it from the moisture.
This collects the draining from the paper whilst drying, and prevents a
loss of silver, since it can subsequently be detached and placed amongst
the residues for burning.
[Illustration: _Fig._ 7.]
[Illustration: _Fig._ 8.]
There is another mode of floating large sheets of paper, which is
sometimes recommended. One corner is turned up about a quarter of an
inch. This is held by the forefinger and thumb of the left hand, and the
opposite corner of the diagonal held by the right hand. The first corner
is brought on the solution near the opposite corner of the dish to that
towards which it will eventually be near. The sheet, having assumed a
convex form, is drawn by the left hand across the dish, the right hand
being gradually turned to allow the whole surface to come slowly in
contact with the solution. Air-bubbles are said to be avoided by this
means, though for our own part we see no practical advantage in it over
the last method.
[Illustration: _Fig._ 9.]
Some operators also, when lifting the paper from the dish, pass it
over a glass rod placed as in the figure, in order to get rid of all
superfluous fluid from the surface. This is a poor substitute for
withdrawing the paper slowly from the dish, since capillary attraction
is much more effective and even in its action than this rude mechanical
means. By those who do not possess patience, however, it may be tried.
Some practical photographers also "blot off" the excess of silver,
but this is a dangerous practice unless there is a certainty that no
"anti-chlor" has been used in preparing the blotting-paper. For our own
part we recommend the usual mode of draining the paper. When surface
dry, it can be dried in a drying box. The following is a kind which has
been adopted by one eminent photographer, and is excellent in principle.
Over a flat and closed galvanized iron bath erect a cupboard. Fig. 10
gives the elevation, and fig. 11 the section. A is the bath, D the
cupboard, which may conveniently be closed with a roller shutter,[17] B,
passing over _c c_, and is weighted by a bar of lead, so as to nearly
balance the weight of the shutter when closed. A couple of Bunsen
gas-burners, E E, heat the water in A; the steam generated is carried
up the flue F, which also carries off the products of the combustion of
the gas. The paper may be suspended from laths tacked at the top of the
cupboard by means of American clips.
[Illustration: _Fig._ 10.]
[Illustration: _Fig._ 11.]