Chapter 8

To tone, the plate is immersed for, say, ten minutes in A, then, after rinsing slightly, it is placed in B for the same period, rinsed again and flowed with C until the desired color is obtained. The tone is a splendid purple black color. If a solution of pyrogallol be substituted to that of gallic acid, the tone is green, and to a green bordering to black when a solution of catechu is used, the catechu exerting at the same time a tanning action on the gelatine. After toning, the plate should be thoroughly washed.

A similar process consists to wet the plate under the tap, then to flow over a mixture by about equal volumes of

A. Ferrous sulphate 5 parts Acetic acid, No. 8 5 parts Water 100 parts, filter B. Gallic acid 5 parts Water 100 parts

When toned, the plate is well washed, then flowed once with the alum solution and again washed. The tone by this process easily turns to an inky blue not very agreeable. The action should be stopped a little before the desired color is obtained.

It sometimes happens that the image in drying intensifies more then necessary. It can be cleared with a solution of oxalic or citric acid.

A brown sepia is obtained by toning first with potassium permanganate, 1 per cent. of water, then, after washing, with a solution of pyrogallol. If gallic acid be used instead of pyrogallol, the tone is black. By this process a great intensity is obtained. A dilute solution of ammonium sulphide can be employed as a clearing agent.

Pyrogallol and silver nitrate give a warm black tone.

Potassium bichromate followed by silver nitrate form a brick-red precipitate of some opacity.(34)

Chloride of nickel and potassium ferrocyanate produce a fine brown.

Lime water and alizarine dissolved in alcohol dye violet.

Alizarine and the caustic alkalies produce a variety of tints, from violet to purple, according to the concentration of the solutions.

Lead acetate and alizarine in ammoniacal solution dye purple.

Potassium ferrocyanide and uranium nitrate produce a warm sepia tone. With chloride of nickel the tone is brown.

Ammoniacal solution of coralline diluted with water gives carmine red.

Potassium bichromate and extract of indigo produce a fine greenish tone suitable for landscapes.

Extract of indigo colors blue(35)

Some of these reactions can be applied to the printing processes with the bichromates, etc. The paper should be coated with galatine. See the Appendix.

Other colorations can be obtained with dyes in utilizing (as shown by Persoz) chromous chromic oxide as a mordant: alizarine, Brazil and yellow wood (morus tinctoria), Fustet (rhus cotinus), etc. The extent of this work does not admit of describing the numerous processes which can be employed; they will suggest themselves to the chemist.

The alkalies employed with the dyes should be employed in diluted solutions, as being liable to produce reticulation. By applying the coloring matters and the mordants thickened with a little starch, the image can be colored with different colors. Lantern slides can be thus colored with great ease.

PREPARATION OF RED, YELLOW, OR BLUE TISSUES.

_Red Tissue.—_Dissolve 10 grams of carmine in 1 liter of aqueous ammonia and evaporate. When the smell of the alkali has almost disappeared, add 1 liter of rain water. Of this take 65 cubic centimeters, add 35 c.c.m. of rain water, and in the solution let soak for an hour 15 grams of very soluble gelatine, add 1 gram of sugar, and dissolve in a water bath. Filter, and take of the mixture a sufficient quantity (25 c.c.m. for a surface 18×24 centimeters) to cover a sheet of paper which has been previously applied upon a glass plate in the following manner: In a tray full of hot water, immerse the plate and the paper; remove the whole in such a manner as the paper remains in contact with the plate; rub out the excess of water with a squeegee, and flow the gelatine over the paper still damp. Let cool on a leveled stand, and when the gelatine is solidified to a consistent jelly, remove the paper from the plate and place it to dry in an oven heated at not over 24 or 25 deg. C.

It is desirable that in drying the paper does not curl up. To that end, apply over it, before it being removed from the plate a wooden frame to which the gelatine, still sticky, will sufficiently adhere to hold the tissue when it stretches in drying.

_Yellow Tissue.—_Pulverize to an impalpable powder 25 grams of light chrome yellow in tablets (water color), and gradually add in stirring 1 liter of rain water. Take 100 c.c.m. of this and into it let soak for an hour 15 grams of the same gelatine used for the red tissue, add 1 gram of sugar, then proceed as above.

_Blue Tissue.—_In a liquid consisting of 85 c.c.m. of rain water and from 12 to 15 c.c.m. of blue ink, such as sold by stationers, let soak for an hour 15 grams of the same gelatine and 1 gram of sugar, and proceed.

_Preparation of Transfer Paper.—_Two kinds of transfer paper are employed—the enamel and plain transfer paper.

To enamel the paper: Dissolve 100 parts of barium nitrate in 500 parts of water, and, on the other hand, 200 parts of sodium sulphate in the same quantity of water. Mix, wash well the precipitate—barium sulphate—by decantation, and when well drained, mix to the following solution:

Gelatine, Coignet’s 300 parts Glycerine 80 parts Ultramarine blue 1 part Crimson lake 0.1 part Water 2,500 parts

Let soak the gelatine for, say, one hour, dissolve by heat, then add by small quantities, stirring violently, 4 parts of chrome alum dissolved in 250 parts of hot water. Filter through flannel and coat the paper as directed to prepare the tissue. The mixture should be employed immediately after adding the chrome alum.

The plain transfer paper is prepared in the same manner, leaving out the barium sulphate and the coloring matters.

_Preparation of the Silver Paper.—_Immerse the paper for two minutes in a solution of—

Sodium chloride (common 2 parts salt, dry) Lemon juice 1 part Water 100 parts (filter)

When dry and wanted for use, sensitize the salted paper by floating for one minute on—

Silver nitrate 8 parts Nitric acid 0.1 part Water 100 parts

On its removal from the silver bath, sponge the paper between sheets of blotting paper and hang it up to dry.

ENCAUSTIC FOR SINGLE TRANSFER PROOFS. White wax 25 parts Mastic 3 parts Turpentine 100 parts

Dissolve by heat, first the mastic, then the wax, and keep for use in a large mouthed vial.

MATT VARNISH. Sandarac 6 parts Mastic 6 parts Lavender oil. 0.5 parts Ether 100 parts

When dissolved, add 30 parts of benzine. The opacity of the film varies with the quantity of benzine added; by excess the varnish dries transparent.

WATER COLORS WHICH RESIST THE ACTION OF LIGHT. Red. Indian red. Light red. Orange. Mars yellow. Blue. Cobalt blue. French blue. Smalt. New blue. Brown. Raw umber. Burnt sienna. Green Terre verte. Yellow. Cadmium Yellow Roman ochre. yellow. ochre.

APPENDIX.

Although we intended to only describe the printing processes without the use of silver salts, we thought it would be well to complete this work by giving the most practical and interesting processes ever published to obtain permanent photographs; as they may give rise in the hand of experimenters to useful applications.

From time to time processes are published under “queer” names, which are based on the well known actions of reagents on the ferric salts reduced by light. They are derived from those described in the following pages.

We call specially the attention of the reader to the process of Poitevin, by which one can experiment with every ferric salts, citrate, lactate, oxalate, tartrate, benzoate, etc., by simply exciting with the corresponding acid. Observe that to obtain good results the paper should be strongly sized; it is a sine qua non, although not recommended by Poitevin.

C.J. BURNETT’S PROCESS(1857).

“A capital process for many purposes,” says Mr. Burnett, “is to float or _steep_ the paper in a mixed solution of bichromate of potash and sulphate of copper, as for Hunt’s chromotype process.(36) I have mixed gelatine, or occasionally grape sugar, or both with the solution;(37) but instead of developing it with nitrate of silver, as in chromotype, wash out the salt unaltered by light, and develop by floating on a solution of ferrocyanate of potassium. The purple red color of the copper salt which now forms the picture may be modified or changed in many ways,(38) viz., by soaking the picture, after the ferrocyanate of potassium has been washed out of the lights, in a solution of sulphate of iron. Solutions of gallic acid, tannic acid with alkalies of carbonate, may also be employed to modify or change the color. This process has the advantage that one may regulate the exact tone (black or useful neutral tint) to the greatest nicety by the time we allow the print to remain in the iron toning bath.”

GODEFROY’S PROCESS (1858).

Float the paper upon the following solution for three minutes and hang it up to dry:

Uranium nitrate 30 to 60 parts Silver nitrate 8 parts Water 100 parts

(39)

The sensitiveness increases in proportion to the quantity of uranium nitrate. With the above formula the paper can be exposed in the camera, or, for printing, under a negative cliché.

In printing an exposure of five seconds in diffused light gives an image perfectly visible, and a grayish black tone; ten seconds gives a vigorous image almost of a black color; in from fifteen to twenty seconds the image is very strong, with the color of an engraving. In sunshine the action is necessarily much more rapid.

The impression is developed by immersion in

Ferrous sulphate 8 parts Tartaric acid 4 parts Sulphuric acid 1 part Water 100 parts

The image is rapidly developed. It is fixed by washing in water.

DE LA BLANCHERE’S PROCESS (1858).

Uranium nitrate 25 parts Distilled water 100 parts

Filter the solution and keep it in the dark.

The paper should be sized with a gelatine solution at 5 per 100 of water, and, when dry, kept in the dark.(40) It is sensitized by floating five minutes.

The exposure under a negative varies from fifteen to twenty minutes in the shade, and from one to three minutes, at the most, in sunshine. As a rule, it is advisable to somewhat underexpose in order that the development be regular, progressive, under control.

The image is developed by floating, or immersion in

Silver nitrate 2 parts Distilled water 100 parts Nitrate acid, C.P. a trace

When the image is intense enough it is washed in several changes of water, then toned in a solution of gold at 1 per 1,000 of water acidified with traces of hydrochloride acid.(41)

The following bath develops slowly, and gives very rich purple tones without toning:

Nitrate of silver 3 parts Nitrate of uranium 1 part Nitrate of cadmium 1 part Alcohol 10 parts Water 100 parts Nitric acid traces

_The developing solutions should be as little acid as possible, but not neutral, for then the proofs would be veiled and grayish._

The image can also be developed in a solution of gold, or in a very weak solution of mercuric chloride at 1 per 10,000. The proof must be extremely well printed and left for from two to five minutes in the mercuric solution. If the time of exposure is right, the image will change but little in the solution, and will take, when treated with silver nitrate, the most splendid tones.

The proofs should be carefully washed when finished. If they were developed with silver, they must be immersed in diluted aqueous ammonia, which will perfectly clear the whites. If developed with chloride of gold, the water should be heated to 60 to 80 deg. C. (140 to 176 deg. Fahr.)

HOUDOY’S PROCESS (1858.)

The paper is floated upon a lukewarm solution of gelatine at 5:100, and when dry, on a bath of uranium at 10 or 15 per 100 of water. After exposure to the sun the image is developed with a solution of silver nitrate acidified with acetic acid. The exposure varies, according to the nature of the negative, from one to ten minutes; it must be long enough for the image being developed in from thirty to forty seconds. It is then removed from the silver bath and placed in the following:

Ferrous sulphate 3 to 8 parts Acetic acid 2 parts Water 100 parts

In this bath the image takes a great vigor and appears entirely on the surface of the paper. When the proof has been too long exposed it should be washed slightly before placing it in the iron bath. Developed, the image is, generally, of a sepia tone, which can be turned to black by a solution of chloride of gold, 1:1,000, washing afterwards as usual.

NIÈPCE DE ST. VICTOR’S PROCESS (1859).

Red Prints.

Float the paper for fifteen or twenty seconds on a 20 per cent. solution of nitrate of uranium and dry before the fire in the dark room. This paper can be prepared many days before use. Expose in sunshine from eight to ten minutes, according to the intensity of the light and the quality of the negative, then wash in moderately warm water (50 to 60 deg. C.) for a few seconds. This done, immerse in a solution of red prussiate of potash at 2 per cent. of water; in a few moments the proof will become of a fine blood-red color, like “sanguine.” Wash, etc.

Green Prints.

Make a red print as above described, immerse it for a few minutes in a solution of nitrate of cobalt and dry it without washing. Fix then in a solution of sulphate of iron at 20 per cent. of water and 4 of sulphuric acid. Wash and dry before the fire.

Violet Prints.

Prepare the paper in the uranium bath, expose, wash and develop in a solution of chloride of gold, 1:200, until the proof has assumed a fine violet color. Wash in several changes of water.

Blue Prints.

Sensitize the paper with a red prussiate of potash solution at 20 per 100. Let dry, expose until the proof is slightly blue; immerse it for five or ten seconds in a saturated solution of bichloride of mercury, wash only once and immerse in a solution of oxalic acid—saturated when cold—heated to about 55 deg. C. Wash in three or four waters and let dry spontaneously.

Black Prints.

Float the paper on a mixture by equal volumes of a solution of iron perchloride and another of uranium nitrate, each at 10 per 100 of water. Expose and develop on a saturated solution of gallic acid.

DR. T.L. PHIPSON’S PROCESS (1861).

Take a solution of perchloride of iron and, having precipitated the peroxide with ammonia, collect the precipitate on a filter and wash it with boiling water. Add the precipitate in excess to a warm solution of oxalic acid. A beautiful emerald green solution is obtained, which must be a little concentrated by evaporation and then set aside in a dark room for use. The paper is floated for ten (?) minutes upon the green solution of ferric oxalate, to which has been added a little oxalate of ammonia and hung up to dry in the dark.

Expose under a negative for from ten to twenty minutes, according to the weather, and wash well the paper with rain water. Spring water will not do on account of the lime it may contain, which will form oxalate of lime in the paper (insoluble). When all the non-decomposed oxalate is washed from the proof, a feeble image of oxalate of protoxide of iron, scarcely visible, is left on the paper. To develop it and to obtain the vigor, the tone and color of silver prints proceed as follows:

Plunge the proof for a little while in a (weak) solution of permanganate of potassium to which a few drops of ammonia have been added; in the bath the image becomes brown and distinctly visible. It is then withdrawn and immersed in a solution of pyrogallic acid for half an hour, after which it is washed and dried.

The image thus obtained can hardly be distinguished from silver prints; the tone is soft, brilliant and permanent.

This process is quite original and interesting. The theory is as follows: Under the action of light the ferric oxalate is reduced in the ferrous salt, insoluble, which, after the print has been cleared from the ferric oxalate, is oxidized and reduced into ferric oxide by the alkalized permanganate, the latter then forming colored compounds with reagents.

It has been lately published in England under the name of “kallitype,” a new process—or old, ad libitum—which consists in developing the image in ferrous oxalate by a peculiar silver compound whose formula is given below. The paper is prepared by brushing with a strong solution of neutral ferric oxalate dried rapidly—which is a sine qua non when using deliquescent salts; and after exposure the image is developed, etc.

Silver nitrate 50 grains Sodium citrate 800 grains Potassium bichromate 1 to 2 grains Water 10 ounces

“Dissolve the silver nitrate in 1 ounce of water, the citrate and bichromate in the remainder and mix. The precipitate—silver citrate and chromate—is then dissolved by adding 1 dram of ammonia .880, and after 35 drops of strong nitric acid has been added the solution is ready for use.”

This process reminds us that of Robert Hunt (1842), and that of more recent date (1863), of Borlinetto, who developed the image in black with a silver nitrate alcoholic solution, 1:500, and after washing the picture in a solution of citric acid, 1:10, fixed it by aqueous ammonia. But, although that is not absolutely necessary, we would advise one working this, or similar processes in which a silver salt is employed for developing, to fix the image, after treatment with citric acid to clear the proofs from iron salts, in a solution of ammonium sulphocyanate—which has not the injurious effect of sodium thiosulphate (hyposulphite)—in order to prevent the paper to be tinged by the reduction of the silver nitrate which is mechanically retained in its fiber.

The solution of ammonium sulphocyanate should be compounded with auric chloride to tone the picture at the same time it is fixed; thus:

Ammonium sulphocyanate 35 parts Gold terchloride 0.15 part Water 350 parts

The solution can be used over again.

In the processes devised by Dr. Phipson, Monckhoven and other authorities, the double ammonio-ferric oxalate is rightly recommended instead of the simple oxalate. Not only is the preparation more sensitive to the luminous action, but better half tones are obtained. As usual, it is advantageous to size the paper with starch.

The ammonio-ferric oxalate is prepared by precipitating ferric chloride or sulphate by aqueous ammonia, then washing the precipitate collected on a filter until the washing water be neutral or does not evolve the smell of ammonia. The precipitate is then placed in an evaporating dish, and by small quantity is added a hot solution of ammonium oxalate until it is nearly (not entirely) dissolved, when the solution is set aside for a few hours, then filtered and evaporated to crystallization. For use, the crystals of ammonio-ferric oxalate are dissolved in the proportion of 1 for 5 of distilled water. The solution as well as the crystals should be kept in the dark.

If one object to the trouble of crystallizing, the solution can be prepared by dissolving the ferric oxide in a hot solution of 30 parts of ammonium oxalate and 25 parts of oxalic acid in 180 parts of water observing that the oxide must be in excess.(42)

The following sensitizing solution gives also excellent results:

Ammonio-ferric oxalate 10 parts Ammonio-ferric lactate 4 parts Water 100 parts

After exposure, which varies from five to ten minutes, according to the intensity of the light and the printing quality of the negatives, the picture appears negative from formation of ferrous oxalate. It may be developed in a great many ways: by a solution of silver nitrate at 2 or 3 per cent. of water acidified slightly by an organic acid—citric acid, for example—or a diluted solution of ammonio-nitrate of silver, which most likely constitutes the best developer; the image is black and consists of metallic silver and ferric oxide, with formation of silver oxalate, which dissolve in the ammonia. If the print be treated by a weak solution of aqueous ammonia, the image turns green, then brown, and if, before the latter coloration is obtained, gallic acid or pyrogallol be added, the image becomes bluish-black or brown-black. In the same circumstances tannin (gallo-tannin) produces a blue-black image; catechu-tannin(43) and quino-tannin give green, etc. Employed as a developer, potassium ferricyanate develops an image in prussian blue, and auric chloride one in the characteristic violet metallic gold. To fix the images obtained by the latter reactions, it suffices to wash them in a few changes of water, and, if developed with silver, they can be toned by any of the alkaline solutions of auric chloride used in the printing out silver process, etc.

The photographs obtained by all these processes are permanent.

DR. J.B. OBERNETTER’S PROCESS (1863).

Copper chloride 100 parts Ferric chloride, sol. sp. 13 parts gr. 1.5 Hydrochloric acid, conc. 12 parts C. P. Water 1,000 parts

Float the paper on this solution for about two minutes and hang it up to dry. The keeping quality of the prepared paper is remarkable; it has been kept for two years without apparent change; its sensitiveness is at least one-third greater than that of silver albumen paper. Unless developed within an hour or two, the vigor of the proof is much impaired; after twenty-four hours a print can be taken over on the same.

When exposed, only a faint image is visible. It should be fixed in the following solution:

Potassium sulphocyanate 12 parts Sulphuric acid, conc. 1 part Sensitizing solution 10 to 12 parts Water 1,000 parts

A print is floated on this solution, face downward, for three or four minutes, taking care to agitate the liquid as little as possible; the print is afterwards immersed and another one floated in its place, thus proceeding until all the prints are immersed or the solution can hold no more. A fresh solution is then added to strengthen it: the older the solution the more rapidly and better it works. In this developer copper cyanide is precipitated on the parts acted on by light, and this exactly in the proportion to the luminous action. The time of immersion depends on the method selected to finish the proofs; it its from five minutes to half an hour. If the proof is immersed for, say, twenty-four hours, the image comes out in a relief which may bring the shadows to two lines in depth. When well developed and thoroughly washed, the proof can be dried and the subsequent operations made at any convenient time.

Various processes may be employed to give to these proofs the tone required; thus: the prints well washed are placed in a solution of ferricyanate of potassium at 6 to 12 per 100 of water, where they take a red color increasing in intensity. If left over night the color becomes a splendid velvet deep red with perfect clear whites. To obtain the color of silver photographs one hour’s immersion is sufficient. After this operation the proofs are washed until the water is no more tinged yellow.

By immersion in Ferrous sulphate 100 parts Iron sesquichloride 40 parts Hydrochloric acid 80 parts Water 200 to 300 parts