CHAPTER V.

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.

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.

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.