THE BRITISH JOURNAL OF PHOTOGRAPHY. June 15, 1884, p.207
IT is now time that we turned our attention to the printing of positives on paper, the "end all" of photography, according to Mr. Hughes; although this phrase is by some deemed quite incorrect, the "end all" in their opinion being the giving a receipt for the money received for their labour or skill. Although we have other negative processes to treat of, it is felt to be desirable that the chapter on printing positives be not delayed until these are all explained, as practice in printing may go on simultaneously with experimenting in new or untried negative processes.
Positive printing may be divided into three general heads: First, Printing on albumenised paper; secondly, Printing on plain paper; and lastly, Printing by development.
The first is requisite when the most minute detail and the finest gradation of tint, combined with brilliancy, are desired, and this is the kind of printing most practised at the present time; the ordinary card-portrait and stereoscopic view being printed on albumenised paper. Plain paper is perhaps more to be preferred when the subject is bold and the size large; such, for example, as when a large picture is to be printed from a waxed-paper negative, or when, at any rate the picture is one which is intended for framing, and to be viewed at a distance of some feet--when, in short, boldness and massiveness, without that minuteness of detail so displeasing to certain artists, are the desiderata. Printing by development secures the qualities inherent in plain paper prints in perhaps a greater degree than is obtained by plain sun printing, coupled with the advantage of great rapidity; for where one print may be turned out by the former two methods, a dozen may, by the latter, be produced in the same time. Each having, then, its advantages, we proceed to discuss them in their order as indicated.
This kind of paper differs from all others, inasmuch as it has one of its surfaces sized, coated, or varnished with a layer of albumen, in which has been previously dissolved a hydro-chloric salt, such as the chloride of sodium (common kitchen salt, of ammonium, of barium, or others. When a paper, or a film, impregnated with such a salt is floated on a solution of nitrate of silver, a decomposition occurs similar to that which takes place in a collodion film. Chloride of silver is formed with an excess of the nitrate; and this, on being subjected to the action of light darkens more or less, thoroughly and speedily.
Whatever the custom may have been long ago, few photographers care, now-a-days, to prepare albumenised paper. The great demand, and consequent competition in connection with it, secures to the buyer an article generally good in quality and moderate in price. Of this fact our advertising columns at all times bear ample testimony. However, for the benefit of those who prefer experimenting on the preparation of albumenised paper, the following instructions are given:
Take the whites of fresh eggs, carefully avoiding the presence of any of the yolk, and to each ounce of them (the white of one average-sized egg measures about one ounce) add from five to ten grains of chloride of sodium dissolved in as little water as convenient, for the smaller the quantity of water present the more highly glazed will be the surface of the albumenised paper be; also; the smaller the quantity of salt which has been added to the albumen, the weaker may be the silver bath for sensitising, and vice versa.
This must now be beaten up to a frothy mass. Earthenware pots are manufactured and sold for this purpose, and consist of jars with closely fitting covers, and from the sides of which spikes stick out in considerable numbers for the purpose of breaking the body of albumen in the most perfect manner possible. The albumen having been put into such a jar, simple shaking suffices to convert it into froth in a brief space of time. Where such a vessel cannot be obtained, put it into any convenient dish, and by means of a wooden fork or a bunch of quills, whip up into a dense froth. This is allowed to stand undisturbed, and after a few hours it subsides into a clear liquid, which must be carefully decanted into a flat dish, of sufficient size to hold the sheet to be albumenised. In this operation it is of importance that no air bubbles be allowed to be formed. The paper is now arranged alongside, and the face of each sheet is placed in each a position as to ensure no mistake in coating it with the albumen. Each sheet of photographic paper has a right side and a wrong side; and it requires only the exercise of observation and common sense to distinguish between them. The sheet, being held by two opposite corners, and bent into a curve, is to be laid down upon the albumen. The centre of the sheet comes first into contact with the fluid; after which, first one side and then the other is lowered down. In this operation care must be Taken to avoid air-bubbles, and this is not at all difficult to do when the most ordinary care is taken. The paper, after being allowed to remain for one or two minutes, is lifted up, and dried. The drying should be affected as speedy as possible, either by means of a hot fire or by heat otherwise applied, for on the rapidity of the drying depends, to a great extent, the beauty and brilliancy of the surface.
The paper so prepared will keep good for a long time, and when about to be used must be rendered sensitive. In former times a somewhat strong solution of nitrate of silver (from sixty to one hundred grains in each ounce of water) was employed; but upwards of two years ago, Mr. Coleman Sellers--the talented American correspondent of this journal--in a paper devoted to the discussion of this subject, stated that a solution very much weaker than that hitherto employed would produce equally good results, provided such a substance as nitrate of ammonia were added to it. And since that time the subject has been pretty fully discussed by photographic writers, some of whom have recommended a silver bath as weak as twenty grains to the ounce, with a large admixture of nitrate of soda. The mass of evidence, on the whole, seems at present to preponderate in favour of a bath much stronger. Make, then, a quantity of the following solution:
|Nitrate of silver||60 grains.|
|Distilled water||1 ounce.|
Filter and pour into a flat dish, and in this float--prepared side downwards--a sheet of albumenised paper, the same precautions being observed here as when coating it with albumen. Allow it to remain on the bath for from three to five minutes, after which remove and hang up to dry. For this purpose a rail may be provided with a suitable arrangement for catching the drippings. It is not a bad plan to have a string stretched across the room, each sheet on being prepared suspended by one corner by means of an American clip, a dish being placed: underneath. When the second sheet is ready, the first is pushed farther along the string and the other made to take its place over the dish, in turn giving place to the third sheet, and so on. When quite dry it should be put away into a dark place, or between the leaves of a portfolio, until convenient to use it. It is desirable that it be used as soon as possible after being excited. As it is liable to undergo decomposition, a few drops of acetic acid added to the silver bath enables it to keep good for a few days in a dry place; but in all cases use it as soon after preparation as possible.
The negative being placed in the printing-frame, select a piece of paper of a suitable size, and, having placed its face near to the collodion side of the negative, put on the back of the printing-frame, and screw them in close contact. Expose now to light, and those parts of the paper not protected from its action by the density of the blacks in the negative will speedily become more or less darkened. The back of the printing-frame must consist of two parts hinged together. This allows of an examination going occasionally made without disturbing the position of the negative and print; but it is desirable to examine it as little as possible. Print till it is considerably deeper in tone than would be desired in the finished print, as the subsequent operations somewhat "undo" the printing. In short, let it be printed so deeply that your uninitiated friend at once exclaims that the print is ruined by being too dark. It is now transferred to a dish of water, the object of this being to remove all the nitrate of silver from the film, in which its presence is now no longer of any use. How these washings may be utilised and reconverted either into cash or nitrate of silver, will form the subject of another lesson; meantime, keep all your washings
The print having been washed, is now ready for being "toned," the object of which operation is at once to make the picture more beautiful and more durable. Were it not toned it would, when finished, appear of a red tint, and not at all pleasing in appearance; whereas, by toning, we may obtain tints of almost all kinds--sepia, purple, black, or blue. But this is not all; for the toning imparts to the print the quality of resisting the lowering of tone consequent upon the subsequent immersion into the firing solution, allowing more brilliant pictures to be produced than otherwise could be done; and, as a last advantage, the toning, by causing a deposit of gold on the blacks of the picture, adds very materially to its chances of remaining permanent. The subject of toning solutions has received much attention of late years, and is now reduced to a state of comparative certainty and considerable ease. To reproduce the various formulae which skill has devised and experience attested, would swell the present lesson into undue length.J.T. TAYLOR.
The Author of these lessons--to render them of more service to the class for whom they are intended--will, at the close of each, reply to such correspondence as may arise out of them. Letters addressed to J. T. TAYLOR, Editorial Office of this Journal, 2, York Street, Covent Garden, London, W. C., will meet with prompt attention, and be replied to in this column as fully as their nature warrants.
J. BRYCE--Your suggestion is a good one, and will receive attention.
ROBERT B. sends a transferred portrait of himself and asks what we think of him. He seems to be a good-looking sort of person, and a good photographer, too, if the specimen be his own production.
A. B. C.--Some photographers of experience prefer cyanide of potassium to hyposulphite of soda for fixing negatives, on the ground that, when the latter is employed, it has a tendency--unless when uncommonly well washed out--to bleach the negative.
A FRIEND.--The sunshade of your lens is too short. Extemporise an addition to it b means of a piece of cardboard blackened in the inside. Let it be ouch m will effectually prevent the ass's rays from falling upon the lens else fogged pictures will reader such circumstances be the rule rather than the exception.
AMATEUR (Portsmouth).--When enlarging with a portrait combination arrange the lenses is such a way as to have the uncemented or back lens of the combination next to the picture to be copied. If a picture is to be copied smaller than its present size, then arrange so as to have the uncemented lens in its normal position, that is, next to the sensitive plate.
J.R.C. cannot get details in the blacks of his pictures, which, so far as we can understand him, are positives on glass. He thinks it cannot arise from imperfect exposures, as that has been varied considerably with the same want of success. The cause evidently is, that the developer is washed oft too soon. It must remain on until the details of the shadows become visible, and should fogging set in before this result be obtained, a little acetic acid must be added to the developer, which will then allow the picture to remain clean under a prolonged development.
W.F.--To obtain a collodion giving great intensity, such as to be suitable for copying maps or engravings, iodise with iodides, to the exclusion almost, it not quite of bromides. The presence of bromides renders collodion more sensitive to coloured rays; hence for portraiture and landscapes it is requisite that one or other of the bromides be present in the collodion, To secure a good photograph of the garden to which you allude we advise the addition of bromides in a large proportion. Make an alcoholic solution of bromide of ammonium or cadmium, and add to the collodion by small quantities, making a trial after each addition until you are satisfied with the effect. Also leave it somewhat longer in the exciting bath.