The Art and Practice of Silver Printing

by H. P. Robinson; Sir William de Wiveleslie Abney

A trial print from a negative should first of all be taken, to enable the operator to gauge as to how much is required to be done to it. A piece of sensitized paper of the exact size of the plate is taken and examined by transmitted light in the dark room. If there be any appearance of markings due to bubbles, or of star-like metallic spots, probably due to small particles of iron being in the albumen, it need not be rejected altogether. Should there be any of these defects, the sheet should be placed on one side to cut up into smaller sizes. We will suppose that we are going to print a 15 by 12 negative. A strong frame (of the description given at [page 44]) must be employed, and the thick plate glass carefully freed from all dust, grit, or stains. The back of the negative is then placed in contact with it, so as to occupy the centre of the frame. The piece of sensitive paper is placed over it, and the back placed loosely over it, and is then carried face downward into the place where the printing is to be done, and the frame is placed face downwards on the floor, and left for a few minutes. By this artifice the paper takes the same degree of humidity as the atmosphere, and there will be no danger of any cockling, and consequent (as it is termed) want of contact, between the paper and the negative. This is only necessary when there is any very great difference in the temperature of the drying room and the place where the prints are to be exposed, and in some establishments the difficulty is met by carrying the whole supply of paper in a closed box into the latter place, and allowing it to absorb any moisture that it can take up. In any case, the paper is next to be placed in absolute contact with the negative, and we strongly recommend the use of sheets of blotting-paper cut to the proper size (about four thicknesses will be sufficient), and backed by a thick pad of closely woven and very smooth felt. These latter are rather expensive, but are very durable if ordinary care be taken of them. The blotting-paper is useful in causing contact, and also because any accidental presence of silver nitrate solution on the back of the sensitive paper is immediately detected, and there is, consequently, no danger of carrying it to another print and spoiling it, which it might do were it absorbed by the felt pad.

The back of the frame is then placed in situ, and the hinged cross-piece brought down and secured by the fasteners. If the springs be sufficiently strong, the film of the negative should now be in absolute contact with the sensitive paper. If there be any grit on the plate glass, or adhering to the back of the negative, it is highly probable that the glass plate will crack, and if the plate on which the negative is taken be very curved,[20] the same disaster may be expected. Suppose the day to be bright, and the negative fairly dense, the frame may be placed for the trial print facing away from the sun (if there be any) so that it receives merely skylight, and no direct rays. When the transparent parts of the negative seem to have taken a fairly black or brown colour, the print should be examined. In practice we have found (supposing the printing room be away from the dark room) that a cloth of thin yellow calico is a useful adjunct during the examination. The cloth is large enough to cover the frame and also the head of the operator. One half of the back is loosened and raised, the half pieces are pulled back, and the paper will probably be found adhering to the negative, and may require a little manœuvring to separate it. A very thin slip (of the size of a toothpick) of soft wood, sharpened at one end, is a good implement to employ, as by inserting it the paper can be separated at one corner, and then be raised by the fingers. We have seen some printers blow against the paper, as if they were separating the leaves of a book from one another, but this method is to be deprecated, since particles of saliva are apt to be carried on to the paper with the breath, and to cause spots, which often appear unaccountable. Should the print appear slightly deeper than it is required to remain, it is probably ready to be withdrawn from the action of light, but the remaining half of the paper must next be examined to see whether such is the case. To do this the first half of the pressure-board of the frame which is loose must be pressed down once more into position, the frame reversed end for end, and the other half of the board opened.

If the print is large (say 15 by 12) it is not advisable to look at much of it at once, or for a longer time than can be avoided. It constantly happens that on a warm day the paper contracts during the short time necessary for a proper examination of the print; the consequence is, that the paper does not fall on the same place on the negative when reflected, and the result is a double print on the paper.

The printing being judged to be complete, the paper is withdrawn by taking off pressure-board and pads, and put away for the further operations of toning and fixing. In one establishment we are acquainted with, the prints when taken from the frame are placed in a box the lid of which is pierced by a hole covered with a dark cloth; whilst others keep them in a press of blotting-paper. The great point to attend to, however, is to keep them away from all actinic light; and we should say, further, from all light, since darkened silver chloride becomes oxidized in light which is usually considered to be non-actinic. No doubt every printer is aware that the prints produced from the same negative and on the same sample of albumenised paper similarly sensitized vary considerably in richness and depth on different days. For instance, when the light is bad, and when, consequently, the printing takes a long time, the colour of the darkened surface will be found to be much duller than on a day when the light is powerful. Silver albuminate is much less sensitive to feeble light, whilst in bright light the difference in sensitiveness is not nearly so marked, and this may account in a certain degree for the difference; but if any one takes the trouble to expose sensitised albumenized paper to bright light so as to darken, and then to cover up half, leaving the other half to be exposed to the light coming through ruby-glass, it will be found that there is a difference in colour between the two portions, and on toning the differences will be still more marked. In dull weather the red and yellow rays bear a greater proportion to the blue and violet rays (all of which enter into the composition of white light) than they do on a bright day. It is the blue and violet rays that reduce the silver chloride to the state of sub-chloride, and then oxidize the latter; yet it must be remembered that the red and yellow also oxidize the sub-chloride without being able primarily to produce it. Hence on a bright day, when the printing is quick, the red and yellow rays have but little time to do any work, whilst on a dull day they have plenty of opportunity of oxidizing the sub-chloride as fast as it is formed. The oxidized image is always more difficult to tone than one which is unoxidized, hence the advantage of printing in a good light if possible. The writers believe that one of the principal causes of the variation in tone of silver prints, which is only too often to be seen, is caused by this difference in length of exposure to the light.

The operator must now be supposed to be cognizant of the operations of toning and fixing which are to be described in subsequent chapters, and that he has the finished trial print of the particular landscape negative before him. He sees whether the middle distance or far distance is obtrusive, and notes which portions require to be softened down by tissue paper, or to be brought nearer by strengthening the high-lights, and eventually forms a picture of it as it should be, centring his imagination in it as built up round the point of principal interest. He endeavours to see whether the sweeps of light and shade lead up to this principal object in the view, and whether, if light, it is in contrast with an immediate dark part of the picture, or vice versa.

Knowing that this is one of the laws of art, he next should endeavour practically to give effect to his imaginative picture by the judicious manipulation of tissue paper, the crayon, and the paint, such as described in [Chapter IX.] The next point to attend to is as to whether the picture requires clouds or not, and if he have a stock of cloud negatives of the right size, he must endeavour to pick out one, a portion of which will compose well with the lines of the picture,[21] and at the same time be correct as regards light and shade. When such a negative is selected, it remains to print it in. A white sky is an abomination, and a plain tinted one without gradation is nearly as bad. If, therefore, the operator has the heart and means to do this double printing, he should never neglect to do it.

But we would here remind him that when a sky-negative has been used with a particular view, it should always be devoted to that landscape. Nothing could be in worse taste, or further from nature, than to use the same sky with different landscapes. We once saw a frame of sixteen views, thirteen of which were backed with the same sky; this was bad enough, but the absurdity went further, and in the same exhibition were landscapes by another photographer with the same sky! The inference is that both these photographers bought their sky negatives, printed them, and exhibited them as their own—a proceeding to which a harsh name might be given. To use a cloud negative properly, the reader should consult the chapter on "[Combination Printing]."

There is another artifice, however, that does away with the blank sky. It is practised by some of the leading photographers in England, and may be put in requisition instead of the more elaborate double printing. In order to do this, a not quite opaque sky—that is, one which "prints in" a little—is necessary. Very effective clouds may be produced by a paint-brush and lamp-black, Indian ink, or gamboge, by painting them artistically at the back of the negative. It matters not if the clouds so formed show sharp lines and dots, since, if the printing be done in diffused light, the thickness of the glass plate on which the negative is taken shades these off, and gives them the soft edges which are natural to clouds. The clouds may take any of the usual shapes as seen in nature, and the paint should not be applied too strongly, but should have a certain amount of transparency. In some negatives we have seen taken on dry plates, the sky was very transparent, and, when printed in the ordinary manner, showed a good deal more than perceptible tint. Yet, by a judicious masking, fleecy clouds floating in a light sky were produced, which deceived the greatest connoisseurs in such matters.

We will now describe how such a negative should be prepared for printing.

Black varnish should be carefully run round the sky-line on the face of the negative, for about a quarter of an inch. On the back of the negative the medium should cover the sky to within one-eighth of an inch of the sky-line, and by this means a sharp but slightly softened edge of the distant landscape was projected. The breadth of the black varnish border on the back was slightly greater than that on the film side of the negative, being about an inch. A piece of cardboard was also roughly cut out to the sky-line, and left sufficiently broad so as to more than cover the sky when laid flat on it. The negative with the clouds painted on it was now placed in the pressure-frame, with the sensitive paper in contact with it. Outside the frame, and corresponding with the sky-line, the edge of the cardboard was placed, a small bar to act as a weight was placed across it as shown in the figure, and the top end supported by a couple of wooden pegs. The printing took place in diffused light. When the picture was withdrawn from the frame, the sky, being shaded gradually by the card, was printed in lightly, whilst the remaining portion of the negative received the full light; the sky, as is right it should be, was darker near the zenith than toward the horizon, where it was, in fact, white; but since the clouds were printed in at the top, the baldness of the white sky was avoided.