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STEREOSCOPIC PHOTOGRAPHY.
PRINTING ON ALBUMENIZED PAPER.
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THE
Photographic Instructor,
FOR THE
PROFESSIONAL AND AMATEUR,
BEING THE COMPREHENSIVE SERIES OF
PRACTICAL LESSONS ISSUED TO THE
STUDENTS OF THE CHAUTAUQUA SCHOOL
OF PHOTOGRAPHY,
REVISED AND ENLARGED,
EDITED BY
W. I. LINCOLN ADAMS,
Editor of the PHOTOGRAPHIC TIMES.
WITH AN APPENDIX ON THE NATURE AND
USE OF THE VARIOUS CHEMICALS
AND SUBSTANCES EMPLOYED IN PHOTOGRAPHIC
PRACTICE.
BY
Prof. CHARLES
EHRMANN,
Instructor of the Chautauqua School
of Photography.
NEW YORK:
SCOVILL MANUFACTURING COMPANY,
423 BROOME STREET.
1888.
PRINTING ON ALBUMENIZED PAPER.
THE SILVER SOLUTION.
The albumen paper that is sold by dealers has been soaked in an alkaline salt, and when such paper is floated upon a solution of silver nitrate, two compounds are formed; the organic albuminate of silver, and silver chloride, both of which are sensitive to light.
A sixty-grain solution of silver nitrate may be recommended, that is, one which contains sixty grains of silver to the ounce, although a much weaker one will answer the purpose tolerably well. As a matter of course, the bath grows weaker with use.
Such a bath may be made as follows:
| Water .................................... | 64 ounces |
| Silver nitrate ........................... | 8 " |
| Ammonia nitrate ...................... | 2 " |
| Magnesic nitrate ...................... | 1 ounce |
To each ounce of the solution add one drop of strong ammonia. By adding silver nitrate, from time to time, the solution may be kept up to the required standard. This may be ascertained by the argentometer; the figures at the surface of the bath in which the instrument is floated indicating the number of grains per ounce. The ordinary hydrometer will serve well enough, since we may add silver, from time to time, in sufficient quantity to keep the instrument at the same level when floated in the bath. We may, indeed, employ any glass tube closed at one end and open at the other. Cause the tube to stand upright in the liquid by dropping Shot into the open end. The surface of the bath may be marked by a ring of thread, and this mark may afterward be made permanent by a three-cornered file. Of course the tube must always contain shot of the same number and size.
On account of the presence of ammonic and magnesic salts, the argentometer should read, not sixty, but eighty. Only silver nitrate needs be added from time to time, as the solution is not depleted of the alkaline salts, except as the quantity of the liquid is diminished. The best way is to add a quantity of solution compounded as above, and then add silver nitrate to bring the whole up to the required reading on the hydrometer.
The silver-bath should be kept in an alkaline condition by adding, occasionally, a few drops of ammonia. The tendency to become acid is due to the liberation of nitric acid from the silver nitrate.
During the floating of the paper some organic particles pass from the paper into the bath, where they soon decompose and discolor the solution. The bath may be cleared by shaking it up with a handful of china clay or kaolin, which adheres to the particles and carries them to the bottom. The bath should then be filtered, or, when used, it may be decanted, leaving the sediment behind. Better yet, the bath may be drawn from the bottle by two tubes, carried in one cork after the manner of the wash bottle which is so much used in laboratories. One tube is a syphon that reaches to the bottom of the bottle, while the longer arm is outside the bottle and carries the solution into the tray. The other tube passes merely through the cork, and through this a current of air is blown; the pressure from this starts the syphon.
FLOATING THE PAPER.
This must be done in a glass, porcelain or wooden tray. If wood is used, the bottom and sides should be well shellacked. A convenient tray for amateurs is the "Waterbury " tray, of a size large enough to float a whole sheet at a time.
Lift the sheet to be floated by two opposite corners, with the film side down, and let it touch the bath first near one end. Lower the rest of the sheet smoothly and quickly until it all rests upon the bath. Across each end lay a light piece of wood, until the curling of the edges has ceased. These edges may easily be kept down also by breathing upon them. As soon as possible, each corner of the sheet should be lifted and bubbles of air adhering to the film. should be broken with a glass rod, or blown away by a smart current of breath. No drops of the solution should be spattered upon the top of the sheet. The albumen paper commonly sold in the market should be. floated about two minutes in winter, and a minute and a quarter or a minute and a half in summer. For printing with weak negatives, the floating should be somewhat longer.
Withdraw the sheet by grasping two corners with wooden clips and hold it over the bath to drain. It is an excellent plan to draw the sheet over a glass rod fixed across one end of the tray. This scoops all superficially banging silver back into the bath. The sheets may now be pressed between pieces of blotting paper and hung up to dry, being supported by the clips to stretched twine or across wooden rods. The drying should, of course, take place in the darkness, or in extremely weak light.
The albumenized side of the paper, either before or after sensitizing, should not be handled more than is absolutely necessary in cutting it to the proper size. The bands should be clean and dry. The sensitized paper soon becomes discolored and is seldom in its best condition after twenty-four hours. In cold, dry weather, however, it will keep well for several days.
FUMING.
The sensitized paper, after being thoroughly dried, by artificial heat or otherwise, should, before printing, be exposed for a time to the fumes of ammonia. The ammonia is useful in absorbing the free chlorine that is evolved during the exposure of the paper to the sunlight. To this end, secure an old box that is two or three feet long and half as wide and deep. Paste black or brown paper over the cracks, and set the box on end. The front should be removable, and might conveniently work with a hinge. It should fit pretty accurately, and around the margins it would be well to tack a strip of cloth. Instead of this wooden front, a large piece of pasteboard or blotting paper might be used, it being crowded in at the edges and the whole box then covered with a cloth.
Provide the box with a false bottom placed about two inches above the real one. This may consist of a porous cloth stretched across, or of a perforated thin board or pasteboard. The perforations should be numerous.
The paper is placed in the box by putting two sheets back to back and hanging them, by means of clips provided with books, to twine stretched back and forth across the top of the box; or, the sheets, back to back, may be pinned through the corners to the sides and top of the box. A large number of sheets may be fumed at one time. When all are in place, put a shallow tray or plate containing strong ammonia under the perforated bottom and close the front. The paper should fume about fifteen minutes in warm weather, and nearly double the time in cold weather. After fuming, a short time should elapse before printing, to allow the paper that is moist with the fumes of ammonia to contract and resume its normal size.
PRINTING.
The word " printing," as used in Photography, is a misnomer. The word, as seen in its etymology, means, properly, to take an impression by some mechanical means. But photographic "printing" is a process of reproduction by a chemical change that is effected in a sensitized surface through the agency of light; and might therefore be more properly styled CC copying," after the manner of the Germans. The only mechanical changes involved are such as serve to bring the sensitive surface into proper relation to the actinic power of the light.
A frame that is at least one size larger than the negatives to be printed from is a great convenience. In the first place, in the larger frame the negative will be printed to the very margins; and, in the second place, the larger frame will be a great help if you desire to vignette upon your print clouds from another negative. A clear glass plate of the same size as the frame may be used to support the smaller negative.
Place the negative in the frame, film up, and upon it lay the paper with the sensitive surface down, that is, next to the negative. Put the back of the frame in its place and press it down with the springs. The frame is now ready to be exposed to the light.
The change effected by the light in the sensitive film may be expressed by the formula:
Ag Cl + sunlight = Ag + Cl.
We see that free chlorine is evolved and metallic silver deposited. It is this fine deposit of silver that constitutes, by its greater or lesser amount, the lights and shadows of the picture.
If the negative is very weak and flat, that is, lacking in contrast, it were better not to print by direct sunlight; otherwise, the exposure may be made to the direct rays of the sun. To effect this, a wide board may be thrust out of a window having a southern exposure. It is better yet, however, to nail together three boards in the form of a right- angle triangle, and so place the triangle in the open window that the hypotenuse is perpendicular to the line of the sun's rays. Strips may be nailed across the board for supporting the printing frame.
The progress of the printing must be carefully watched. Withdraw the frame from time to time into the diffused light of the room, slip the spring, raise one end of the back, and examine the print. The print when ready to be taken out should be considerably darker than the finished picture is to be. This excess of blackness will disappear in the subsequent washing and fixing. Rather weak and flat negatives should be printed especially dark, as they lose more of their depth in subsequent operations. Experience alone will determine just bow long to continue the exposure in order to secure the best results.
WASHING THE PRINTS.
The washing may be performed in a japanned or porcelain tray. Lay the prints one by one face down into the tray and press them beneath the water. Twenty-five or thirty may be washed at a time. After being placed in the tray they should be moved by slipping them from the bottom and placing them upon the top. After standing eight or ten minutes the water may be poured off and a fresh supply added. The same manipulation should be performed with each washing as with the first. Into the fourth wash a quarter of an ounce of saturated solution of sodic bicarbonate and half an ounce of saturated solution of common salt may be placed. The soda will bring the prints into an alkaline condition that is favorable to the action of the toning-bath. The prints should remain in this mixture not more than five minutes, and should then be well rinsed. They are then ready for the
TONING-BATH.
The office of the gold toning-bath is to substitute for the reddish, disagreeable color of the print a bluish or brownish black. The chemical change involved is not at present very well understood.
It is a prime requisite of any toning-bath that it be slightly, but decidedly, alkaline. It should be tested from time to time with litmus paper, especially if it does not act properly.
Many toning-baths are in use and they differ somewhat in results. We will describe but one or two.
STOCK SOLUTION.
| Water | 15 ounces |
| Chloride of gold and sodium | 15 grains |
To make up a toning-bath for twenty prints, take
| Water........................................ | 10 ounces |
| Sodic bicarbonate......................... | 3 grains |
| Sodic chloride (common salt) .......... | 6 " |
| Stock solution of gold ................... | 3 ounces |
A good pinch of sodic bicarbonate and of sodic chloride will be sufficiently accurate. To this bath add three ounces of the stock solution of gold that has first received three drops of a saturated solution of bicarbonate of soda. This last is to maintain the alkalinity of the bath.
Another excellent toning-bath is as follows:
STOCK SOLUTION.
| Water ............................................. | 15 ounces |
| Chloride of gold and sodium ................. | 15 grains |
Pour three ounces of the stock solution into the toning-tray and render it slightly alkaline by carefully adding a saturate solution of sodic bicarbonate. Then add a pint of water and about twenty grains of sodic acetate. After standing half an hour this bath will be ready for use.
Lay the prints in the bath one by one, face down, and move them continually, so as to avoid sticking together of the prints, and consequent unevenness of tone. Ten or twelve may be toned at one time, and as these are taken out others may be added. If the bath becomes very weak and slow in its action, provided excessive cold be not the cause, more gold should be added.
In ten or fifteen minutes the reddish color should begin to disappear and to be gradually succeeded by a rich purplish black in the shadows. The prints should not be withdrawn from the bath until this stage has been reached. On the other hand, they should never lie so long as to acquire a bluish or slaty color.
As heat accelerates chemical action, it is important that the bath be kept at about the same temperature as the room, sixty-five or seventy degrees. To effect this the toning-tray may be set on a hot soapstone ; or, better yet, as some one has suggested, the tray may be set across a small open cask, in the bottom of which stands a burning lamp; but the bath must not be overheated. The prints must be examined in light strong .enough to enable the operator to judge accurately of the tone. After thorough rinsing the prints are ready for the
FIXING-BATH.
The office of the fixing-bath is to dissolve the silver chloride not acted upon by light; without which the picture is subject to further light-action, will consequently not retain its brilliancy and definition, and will, in fact, assume a dark color all over.
One of the products of the fixing process is a double salt, the argento-sodic hyposulphite, which is again soluble in an excess of sodium hyposulphite, and must be totally removed from the print by subsequent washing, to secure its perfect permanency.
The following bath is recommended:
| Water............................... | 1 gallon |
| Sodic hyposulphite............... | 1 pound |
| Sodic bicarbonate................ | 1 tablespoonful |
| Common salt...................... | 1 " |
The prints should be placed in the bath one by one, enough of the liquid being used to cover them well. Move them frequently, as in toning, to prevent sticking together. They should lie in the bath not less than fifteen minutes. It is better to prolong the time to twenty minutes, if the bath is rather cool. The bath should be made up some hours or days beforehand, as the dissolving of the crystals lowers the temperature materially. The fixing-bath should be thrown away after once using. The fixing-tray should, under no circumstances, be used for any other purpose.
To insure against blistering, it is well to transfer the prints from the fixing-bath into a strong solution of common salt, in which they may lie three of four minutes.
They are then ready for their final
WASHING.
A limited number may be washed well enough in a tray. Rock the tray occasionally, or move the prints by continually slipping out the bottom one, and placing it upon the top. The water should be changed seven or eight times, and during the earlier part of the process the changes should be more frequent than during the latter part. A thorough elimination of the fixing solution is essential to the permanence of the photograph. There is little danger, therefore, of continuing the washing too long. Some even allow water to run over the prints all night. It is supposed by many, however, that an excessively prolonged soaking in water weakens the print.
The object of washing the print is to remove from it all sodic hyposulphite and the derivatives of the fixing process. A test for perfect elimination is the iodide of starch paper of dark purple color, which, when brought into contact with prints, or the water dripping from them, will bleach immediately if only a trace of hyposulphite be present.
To remove these last traces of the obnoxious salt, a tablespoonful of Flandreau's S. P. C. Hypo Eliminator, added to one quart of the last washing water, and allowing the prints to remain therein for a few moments, and then rinsing them off again with pure water, will effect a thorough elimination, without which albumenized paper prints will always be liable to turn yellow or to fade.
The eliminator should not be used in large proportions, as by too strong solutions the whole silver deposit might suffer.
STEREOSCOPIC PHOTOGRAPHY.
This class of photographic work, so far as the making of the negative is concerned, is the same in all its details as the negative-making already described.
The only difference in apparatus is found in the use of two lenses, in all respects exactly alike, and placing in the camera, exactly in the centre, a partition of such length and width as to keep the images thrown by the lenses from interfering the one with the other. The usual 5x8 camera is well suited for this style of work; better yet, so far as economy is concerned, is the size known as 4 1/4 x 6 1/2.
The cut illustrates fully the style of camera required for this work; in it may be seen the central division and the two lenses.
It is self-evident that, by the use of this camera, two negatives are in made of the same view at the same. time, one differing from the other sufficiently to give the relief needed when the print is made, mounted and viewed through the instrument known as the stereoscope.
The difference in the two pictures is well illustrated by holding a book directly in front of the left eye, at the same time closing the Tight eye. By thus placing the book, the back, only will be seen by the left eye; now open the right eye, upon doing which the whole of the right side of the book will be seen, thus relief or solidity is given to the object.
Nothing need be here written as to choice of subject, direction of light, development, or any of the manipulations already given, for the reason, as first stated, that all are the same.
After printing, we meet with the important part of this work in the mounting on card-board. Of this the best size is 4x7. When you are ready to mount the pictures, before cutting, turn each one over and mark the one that is at your right hand with an L, for left, and the other with an R, for right, for when mounted on the card the one that is to the right, as printed, is to be placed to the left on the card ; keep each pair together, otherwise you will have different shades of toning on one card.
Before cutting out you should have a piece of glass prepared to trim by, to measure 21 inches wide and 31 inches high; some workers make it 3 inches wide. As a rule, the firstnamed width is the best. Some people have difficulty in viewing the pictures when too widely separated. This piece of glass may be cut on top at a right angle to the sides, or may be rounded, as suits 'the fancy, but it must be smooth along the edges to render the cutting-out clean; it may be had of the dealer if you do not choose to bother with the making.
The trimming may be done with the Robinson Trimmer before described, or with a knife that has a rounding point, and that is perfectly smooth and absolutely free from any roughness on the edge, otherwise it will tear and make ragged the edges of the print edges
Place upon a sheet of glass the print to be cut; upon the print place the glass pattern by which the print is to be trimmed, hold the pattern firmly and pass the knife closely along the sides of the pattern with a steady but quick movement.
In placing the pattern, be careful to have the base-line the same in both pictures, and use on one side or the other the same object, so that each may contain exactly the same view. This, with a little practice and care, can easily be done.
Viewed in the stereoscope, the picture, if properly mounted, will be most charming; the distance, quite perfect.
There are views without end, anywhere and everywhere, that are suited to this sort of work-little bits, wooded lanes, forest paths, waterfalls, brooks over-hung with trees that possess little charm in a single view, but which are just suited for this style of picture.
Always avoid having the negative very intense; avoid pure whites in the print, for the effect will be snowy; plenty of detail (full exposure); even if the print seems dark, the stereoscope will bring it all out; while if "hard," as we term it (black and white), the effect is not good.
In this style of picture, have, if possible, something prominent in the fore-ground. From this the stereoscopic effect is plainly seen; a bush, a log, in fact any object so placed, seems to lift the whole picture into relief.
Scovill Manufacturing Co.
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