SearchAbout This SiteTreatment ForumVideo clipsGalleryScienceLibraryTechnology

Towler, John. The Silver Sunbeam. Joseph H. Ladd, New York: 1864. Electronic edition prepared from facsimile edition of Morgan and Morgan, Inc., Hastings-on-Hudson, New York. Second printing, Feb. 1974. ISBN 871000-005-9

Chapter XXXII.

THE operation of printing is performed by the direct rays of the sun or by diffused light. Frames of various sizes are to be had of the dealers for this special purpose. These are oblong dishes, about two inches deep, with a pane of plate glass for the bottom, lying upon a ledge loosely. Upon this the negative is placed, collodion side upward, and over the negative the sensitized paper, albumen side downward. A piece of chamois leather, soft cloth or Canton flannel of the size of the pane of glass is placed over the paper carefully, so as to keep it in its position directly over the negative, and to form a sort of cushion when the folding doors, that come next, are fixed in their place. There is quite a knack in adjusting the leather so as not to produce any friction upon the negative, which would certainly injure if it were not varnished. The negative lies as near the middle of the pressure frame as can be, and in the same direction as to length. The folding doors are two thin flaps of wood joined by hinges in the middle, equal in size together, and lying horizontally to the pane of glass. This door is adjusted in its place over the cloth or leather in the following manner. Whilst the outstretched fingers of the left hand are holding the paper and cloth in their places, without the slightest friction, the nearer flap is put in its place and held down by a gentle pressure, whilst the left hand now relinquishes its hold and closes down the other flap. By means of strips of wood, an inch and a half wide, stretching across the frame and (fixed on hinges on one side of the printing frame, and supplied with metallic springs beneath, each flap is pressed down and held in its place by means of a hook on the other side. By such an arrangement it is evident that each folding door is independent of its neighbor, and by opening it the cloth over one half of the negative can be thrown back, the picture can be raised and examined, and again replaced without disturbing the relative position of the paper and negative. So arranged, the printing frame is now exposed to the sun, by rearing it on a shelf at the outside of the window right in front of this orb. The color of the paper will soon begin to change, and soon the whole picture will be apparent. Some negatives produce the best prints when exposed to a very powerful light; others on the contrary require to be printed slowly. A negative which is very dense will yield the best effect by exposing the frame to diffused light; whereas a very thin negative may be exposed to the full blaze of the sun, in order to be printed very quickly. The best prints are obtained from negatives that are neither too dense nor too thin. The frame is taken into a shaded corner of the room from time to time, and one end of the print is examined in order to ascertain the progress of the operation. If the lights are still white, and the shades not yet bronzed in the slightest degree, the print is not yet finished. As a rule it may be concluded that this operation is complete when either the lights have become slightly tinged by reduction, or when bronzing is beginning to appear in any part of the shadows. In this case, take in the frame, and placing it on a table or shelf, remove the folding doors, then the cloth, and finally the print. Be careful not to expose the print to a strong light, otherwise the whites will be injured. Place it between the leaves of a book or in a drawer in the dark-room, until a sufficient quantity has accumulated for the next operation. An experienced printer will be able to obtain satisfactory results as far as circumstances will permit; but it is utterly impossible to force a n inferior negative to yield a superior print; a certain relation, a certain happy relation, (a remark that I have so many times repeated, but not too often,) must exist between lights, middle tones and shades, with a given density of the latter in order to secure normal prints; and where this exists, it is the fault of the printer if he does not arrive at the maximum result of perfection.

Toning of the Prints.

In the dark-room, illumined by the yellow light of a lamp, or by that which passes through the orange-yellow non-actinic glass, examine the points separately, rejecting each in which there is a decided failure, and cut off all extraneous parts that are certainly not required when mounted, allowing, of course, always sufficient margin for the final trimming. Next throw each print separately into a pail or tub of water, taking care that its surface comes in contact with the water, without the intervention of bubbles. Keep the prints in motion by turning them over and over again for the space of five minutes, and afterward take them out separately and immerse them in another tub of ´eater in the same manner as before. The grater from the first pail is poured into a large barrel or tank kept for this special purpose. Move the prints about as before for five minutes, and then proceed to the third pail in like manner. The water from the three pails is poured into the tank, and a tea-spoonful of common salt is added and dissolved by agitation with a wooden stirrer; after the subsidence of the deposit of chloride of silver, the refuse water is allowed to flow off into the sink by a stop-cock inserted within a couple of inches from the bottom of the tank.

Formula No 1. For the Toning Solution.

Chloride of gold, (pure,) 1 grain.
Distilled water, 8 ounces.
Carbonate of soda to neutralize the acidity.  
Alcohol, 2 drachms.

Formula No. 2.

Double chloride of gold and potassium, 2 grains
Distilled water, 3 ounces.
Carbonate of soda, 3-5 grains.

Formula No. 3.

Chloride of gold, 1 grain.
Distilled water, 8 ounces.
Chalk to neutralize the acidity.  
Chlorinetted limp, 5 grains.
Alcohol, 2 drachms.

Formula No. 4. Gold and Uranium.

No. 1. Chloride of gold, (pure,) 1 grain. Filter each and then mix
Distilled water, 4 ounces.
Chalk to neutralize the acidity.  
Nitrate of uranium, 1 grain.
No. 2. Distilled water, 4 ounces.
Chalk to neutralize the acidity.  

Formula No. 5.

Chloride of gold, 2 grains.
Distilled water, 8 ounces.
Phosphate of soda, 100 grains.
Neutralize with chalk.

Formula No. 6.

No. 1. Chloride of gold, (pure,) 2 grains. Filter the latter grains, and mix.
Distilled water, 4 ounces.
Carbonate of soda to neutralize the acidity,
Phosphate of soda, 2 grains.
Acetate of soda, 2 grains
Nitrate of uranium, 2 grains.
No. 2. Distilled water, 4 ounces.
Chalk to neutralize the acidity.  

The acidity of any of the above solutions is neutralized as follows: In the first place throw into the solution a piece of blue litmus paper of the size of a ten-cent piece, its color will be turned red; now throw in either carbonate of soda or carbonate of lime until the blue color is restored. Carbonate of lime (chalk) has this advantage over carbonate of soda, it can be used without litmus paper, taking care only to throw in a superabundance, which does no harm, and can afterward be removed by filtration. I prefer preparing the double chloride of gold and calcium beforehand, and in quantity in a concentrated liquid form. In such a condition a few drops can be added to the toning bath in a moment, whenever it is found that the toning does not commence or proceed satisfactorily.

Pure chloride of gold is a deliquescent salt, is not easily crystallized, and when crystallized is not easily retained in this form. Its color is of a deep reddish color. But the chloride of gold, sold as such, is of a yellowish color, in a dry crystalline condition, and is not deliquescent; it is therefore not pure; it is probably in most cases a double chloride, either of gold and potassium, or of gold and sodium. These double salts are used in toning, as recommended in the above formulae; but it must be remembered, that in buying such an article, double the quantity will be required, and of course you have to pay the price of gold for the soda or potassa in the mixture, which is poor economy.

With any of the preceding formulas baths may be formed which will produce rich tones. Formula No. 5 admits the substitution of citrate of soda, or acetate of soda for the phosphate. The first is the simplest, and I think the most rational; probably the third will please many; its tone is more of a sepia. The aim of the citrate, acetate, and phosphate is to produce a purple tone. The uranium bath produces a rich tone, still I do not think it superior to the simplest alkaline gold bath. Use the bath slightly warm, that is, at a temperature of 90° or 100°. Before the prints are introduced into the toning bath, pass them separately through hot water. Let the bath be sufficiently large to accommodate a number of prints side by side; turn them over continually; keep them in motion. The tone of the prints soon begins to change; before it becomes of a slate blue, take each print out, wash in hot water, and immerse in the fixing bath.

Fixing Solution.

Hyposulphite of soda, 2 ounces. Slightly warm
Water, 12 ounces.
Alcohol, 4 drachms.

The first effect of the toning bath is to change the color to a reddish hue, and then finally back again. Move the prints about in this bath continually, and keep them in until the whites are perfectly clear when viewed by transmitted light, and the tone has been restored. Where the printing has been well performed, supposing the contrast in the negative to be right, the color of the deep shades is but very little changed in the fixing solution, and very soon returns to the proper tone. If the whites are full of gray spots when the prints are placed between the light and the eyes, it is a sign that the fixing is incomplete, and probably too that the prints during the hashing and the toning have been too much ex posed to a strong light. All operations, until the fixing is complete, ought to be performed in a room lighted by non actinic rays. When the tone of the picture and the transparency of the whites are satisfactory, remove the print from the fixing bath and immerse it in a tub of water. Do so with all of them, until the fixing operation is complete. The prints are now kept in motion for a few minutes in the water, in order to remove as much as possible of the fixing solution from their surface. They are then taken out and allowed to drain, and finally immersed in another tub of clean water, where they remain for a number of hours, taking care to move them about, and to turn them over frequently. The water in the washing operation can not be changed too frequently; in fact, it is by far the most desirable plan to have an arrangement by which the prints can be subjected to a running stream of water, which can easily be made in large cities supplied with water works.

The apparatus for this purpose is adjusted on pivots so as to rise and fall like the beam of a pair of scales, and it is put in motion by the weight of the water itself. It consists, in the first place, of a trough of wood of any given appropriate length, as, for instance, three feet; its breadth may be one foot, and its height the same. It is divided into two compartments in the middle, and supported on pivots in the middle of the base-board about six inches above the table or shelf on which it rests; by this means it has an oscillating motion or play of about twelve inches at either end, like a see-saw. This trough is placed so that the middle division is, when horizontal, immediately below the stop-cock; but when one is down and filled with water, and the other up and empty, it is evident that if the stop-cock be open, the water will flow into the- empty compartment until this sinks, which it will do when the other is empty. Each compartment is supplied with a syphon, whose arch reaches to a plane nearly level with the top; the calibre of this syphon is somewhat greater than that of the ingress pipe furnished with the stop-cock. Now when either end becomes filled with water, the latter will rise higher than the arch of the syphon, which will then be filled with water. The longer arm of the syphon passes through the end of each compartment and discharges the water from its corresponding end quicker than the water is supplied to the other end by the stop-cock. By this expedient one end becomes alternately light and heavy, and thus produces a constant oscillation of the whole trough up and down. The prints to be washed are placed in these troughs as soon as they leave the fixing bath, and are thus kept in motion and supplied with fresh water for any length of time. Such a machine is called the

Self-Acting Photographic Washing-Machine

When prints are thus treated an hour's washing will remove every trace of the hyposulphite of soda. They are then taken out one by one and pinned by one corner to slips of wood, or suspended on varnished hooks inserted into corks, as before described in the albumenizing process.

Mounting of Photographs.

Photographs may be cut out of the proper size and shape either before they are starched or gummed or afterward. If before, the following is the mode of proceeding. Place a thick plate of glass before you on the table, on which lay the photograph, picture side upward. Next place over this a heavy mat in such a position as to present the best appearance the print can receive. Holding the mat firmly in its place, by means of the first and second finger stretched far apart, with a sharp-pointed penknife cut along the edge of the mat through the paper to the glass all the distance from the end of the second finger to that of the first. If you stand to perform this operation (a position to be preferred to that of sitting move gently round to the left, still holding the fingers firmly on the mat. Press upon the mat with the right hand, whilst the second finger advances to the position of the first, and this one is again stretched asunder to a new point along the edge of the mat. Now make another incision along the edge in perfect continuity with the first, and thus proceed to the termination. This act of cutting out the prints requires considerable dexterity in pressing the plate, and making the incision so that the terminal cut is a continuity of the commencement, and that the edge all round is clean and not dentated. Where the business is extensive, it is advisable to fix up a special mounting-table like that used by potters for the formation of utensils out of the plastic clay. Such a table can be turned by the feet oil a vertical pedestal, allowing the operator to sit all the time. A whetstone or hone is a very necessary appendage to the mounting-table.

The prints are now turned over and brushed over with a strong solution of gum-arabic, a mixture of gum-arabic and gelatine, or what is still better, with a solution of patent starch or dextrine, such as is used on the back of post-stamps. Where a number of photographs are mounted upon the same paper, it is usual to brush them over on the back with the solution before they are cut out, and when dry to perform the operation just described. The starched surface is then made moist by going over it with a moist sponge. The print is now adjusted upon an appropriate mount and pressed accurately down by placing first a sheet of clean paper over the print, so that its edges overlap the latter, and then holding the first and second finger far apart and firmly on its surface, the print is pressed upon the cardboard by rubbing the space between the two fingers with a burnishing tool or with the smooth handle of a tooth-brush. The fingers then assume different positions, and the burnishing is continued until the whole print is smoothly and evenly adherent to the mounts beneath.

Photographs, after they have been starched, or moistened after starching, can be mounted much more quickly by first adjusting them to their place on the mounts, and then passing them beneath the rollers of a glazing or planishing machine. The two operations are then performed at one and the same time. This planishing is quite au improvement to a print; it is altogether superior to varnishing or glazing. The best rolling machines are those furnished with a horizontal bed, like that in a lithographic press. Still those that consist simply of a pair of rollers are very efficacious in producing decided improvements in stereographs or card-pictures.

Great care is required in keeping out all particles of sand from the starch or gum, for where these appear they produce protuberances on the photographs or apertures when the prints are submitted to pressure in the rolling-machines. It is therefore always necessary to remove them from the starched surface before it is placed on the cardboard, wherever such particles are discovered; and to obviate the repetition of such troubles or diminish their number, it becomes the duty of the operator to cover his gum carefully up when it is not in use.

What to do with the Clippings of Prints.

Spoiled prints, soiled sensitized paper and the cuttings of pictures may as well be preserved as not, for the labor consists simply in placing them in some corner or box, instead of throwing them away. As soon as the stock is very large, they may be burnt in a clean stove and the ashes collected. These ashes contain silver, oxide of silver and other combinations of silver, together with the minerals in the paper, as, for instance, lime, etc. The ashes so constituted are pressed closely and firmly together into a Hessian crucible, then submitted to a powerful heat and thus reduced. Or these ashes may be mixed with the chloride of silver, obtained by precipitation of old baths or at the bottom of the tanks containing the refuse washing water. The mass is first well dried, then intimately mixed with about one half its weight of either carbonate of soda or potassa, and fused.

In large establishments the refuse silver salts, as well as the cuttings of paper, amount to quite a large quantity annually, and are sold for reduction to parties who make it their business. Where such an opportunity presents itself, it is more advantageous to dispose of the unreduced refuse than to perform the operation of reduction one's self.

Mounting Stereographs.

Stereoscopic negatives taken from nature contain two photographs, which, when printed, are inverted, the left picture being where the right ought to be. Some photographers remedy this defect by cutting the negative in two in the middle, and then proceeding from the middle, right and left, two inches and three quarters, the residual slips are cut off' on the ends and thrown aside. The two negatives are now placed upon a thin glass stereoscopic slide, perfectly clean, and side by side in juxtaposition, but inverted, so that the right-side negative is placed on the left side. By means of gummed or glued ribbon on the upper edges, these negatives are held firmly on the slide beneath. The negatives being so arranged, the prints will have the right position, and require only to be pared at the top and bottom previous to mounting. For this purpose a piece of glass, with rectangular corners and ground edges, five inches Ion-and two inches and a half wide, is placed upon the prints on the mounting-table or slab of glass; with a sharp penknife go round the edges, taking care to press the glass form firmly on the prints. In this way the pair of stereographs will be cut out in one piece ready for gumming and mounting. Copies of stereographs (if taken with a single orthoscopic lens) do not require the negative to be prepared as above described; the requisite inversion exists without it.

But in many instances the negative is not prepared at all in this manner for printing, but left in its natural or unaltered condition. In this case (and it is probably the easiest method of proceeding) the glass form is laid upon the inverted print, and the combined prints are cut out; after which another glass form of exactly half the size is laid upon one end of the combined prints, which are then cut asunder. The larger glass form has a notch on the top and bottom edge in the middle; these notches are placed on the middle line of the print, and serve thus to direct its position. If this middle or dividing line between the two prints has considerable width, which is sometimes the case, the glass form must be in proportion longer; but the smaller form retains its size of two inches and a half. Stereographs of groups and of architectural objects are frequently cut out with rounded corners, sometimes on the top only, and sometimes both on the top and bottom. For this purpose you must prepare for yourself appropriate forms of glass, by grinding down the corners on a grindstone, or you can cut out the requisite shaped mats in brass. Those of glass are by far the easiest to construct.

Mounts for stereographs of various shades of color can be had of the dealers; these, being cut by machinery, are neater and cheaper than those you can make y yourself from cardboard. If you do not possess the power, that is, have not cultivated the faculty of seeing stereoscopically without an instrument, you must be very careful not to invert the right and left side pictures between the cutting and mounting. It is well to be provided with two small boxes, one marked left and the other right, into which the corresponding prints can be thrown as soon as they are prepared for mounting. The mode of pasting, adjusting to position, and passing beneath the roller is the same with the stereograph as that with the ordinary photograph, which has been already described.

Home ~ Library ~ Science ~ Technology ~ Gallery ~ Video ~ Forum ~ About ~ Search