Edward L. Wilson

“ In Swan's carbon process the image is produced in the pigments of the painter, and whatever of permanence may be predicated of a water-color drawing, may be affirmed of the photographs produced in the same materials. If carbon be regarded as the most stable coloring matter which can be employed, lampblack or other similar preparations of carbon can be used in the production of the print. Sepia, bistre, Indian-ink, or any combination of these or other pigments, by which a pleasing monochrome may be produced and permanency attained, is equally available in this method of printing. ”

“ There are two modes of proceeding in forming the tissue, either of which may be adopted, as circumstances may render desirable. The first consists in coating a plate of glass with plain collodion, and upon this film applying a mixture of gelatine, sugar, coloring matter, and bichromate of potash. When this is dry, it is removed from the glass, and forms a pliant tissue, ready for exposure under a negative, after which it is mounted (exposed face down) on paper, either temporarily, by means of caoutchouc cement, or permanently, by means of albumen. ”

“ The sensitive tissue, prepared as before described, is, when dry, ready to receive the photographic impression, by exposure under a negative in the usual manner, or by exposure in a camera obscura, to light transmitted through a negative in the manner usual in printing by means of a camera. ”

“ My invention relates to a process by which sheets of various material, such as leather, cloth, paper, etc, are covered by a coating applied in the form of a fluid, or a fluid solution, in such a manner that the resulting coating will be smooth and of uniform thickness, and so that when the solution applied contains chemical salts these will be equally distributed over the surface which is so covered. ”

“ They are these: the image is formed of carbon or other known permanent pigment; the vehicle or menstruum in which the pigment is held is gelatine, rendered quite insoluble by combination with the oxide of chromium; the amount of gelatine present in the image, and uniting it with the paper on which it rests, is not greater than that on the surface of a sheet of well-sized writing-paper, so that there is as little danger of the vehicle cracking or decomposing, as there is of the pigment fading. Absolute imperishability cannot probably be predicated of any picture formed of pigments and paper ”

“ The layer of soluble matter is rendered insoluble wherever the light has penetrated sufficiently through the transparent parts of the negative; but where the more opaque parts of the negative, through which light has penetrated with much less intensity, protect the coated surface, a portion only of the coating is rendered insoluble, that portion being the surface in immediate contact with the negative. ”

“ In coating a surface of paper with the sensitive tissue-compound, I apply the sheet, sometimes of considerable length, to the surface of the tissue-compound contained in a trough, and kept fluid by means of heat, and I draw or raise the sheet or length of paper off the surface with a regular motion ”

“ A Carbon Photograph, in the strict sense of the word, is an image in carbon produced by the action of light. The term, as commonly used by photographers, has, however, a wider application, and is employed to designate any sun picture produced in permanent pigments, whether consisting of carbon or not. ”

“ Those who endeavor to practise it will find it entirely different from the silver process—no gold, no silver, no hyposulphite, entering the construction of a carbon print—yet quite as easy and possessed of many advantages. If what follows should not meet every case, any who may be troubled with failures I shall be glad to answer through the columns of the Philadelphia Photographer, wherein also notes of future experiments, improvements and discoveries in the process shall be regularly recorded. ”

“ It gave pictures of exquisite delicacy and force, rendering perfectly every gradation in the negative with a degree of beauty which had rarely been obtained even by the usual methods of silver printing.
It is unnecessary to enter into a consideration here of the possibility of producing permanent pictures by the usual photographic processes of silver printing. The stigma of instability has been hitherto the chief drawback to the beautiful results of photography. In no silver printing process has immunity from fading been obtained ”

“ In practice the level table top should be made of substances not changeable in form on the application of fluid, and glass, slate, marble, or metal may be used, though I prefer glass. “In applying the solution, which, upon drying, forms the desired coating of the sheet, and where the solution is of such a nature that but a small quantity will leave or deposit the requisite coating, I proceed in the manner of water-color artists when laying broad washes of flat tints. ”

“ In this style of printing, carbon or other coloring matter is fixed by the action of light passing through a negative, and impinging upon a surface composed of gelatine, or other like substance, colored with carbon or other coloring matter, and made sensitive to light by means of bichromate of potash, or bichromate of ammonia, or other chemical substance having like photographic property ”

“ When the photographically impressed, but still undeveloped tissue is to be cemented to a surface, that not only serves to support the picture during its development, but also constitutes permanently the basis of the picture, I prefer to use albumen or starch paste as the cementing medium ”

“ The non-sensitive tissue is made sensitive, when required for use, by floating the gelatinous surface upon a solution of the sensitizer, and the sensitizer that I prefer to use for this purpose is an aqueous solution of the bichromate of potash containing about two and a half per cent, of this salt. ”

“ Swan's process we cannot yet say, but we are assured that no interference whatever will at present be made with any one who may feel inclined to take it up and experiment with it. A great many have already done so, and are also making their own tissue. The making of the tissue is troublesome, and it is more economical to buy it of the dealers. ”

“ One of the greatest hindrances to the progress of the art of Photography, is the doubtful permanency of its productions. It will become an immense power if we can overcome this objection. Its votaries have learned how to secure beautiful lights and shades ”

“ Swan's specification, together with the series of ingenious devices accompanying its use, have been the means of effectually overcoming the many practical difficulties above enumerated, and of making the production of carbon prints, of any size, in any number, and of unimpeachable quality, a thing commercially practicable. ”

“ Or where I employ collodion, with a view to connect the minute and isolated points of the print firmly together during development, I sometimes ultimately remove the film it forms, by means of a mixture of ether and alcohol, after the picture has been finally mounted, and the support of the film of collodion is no longer required. ”

“ Those which have been temporarily mounted, I transfer to paper, card, or other surface. In transferring to paper or card, I coat the surface of the print with gelatine, gum arabic, or other cement of similar character, and allow it to dry. I then trim the print to the proper shape and size, and place its surface in contact with the piece of paper or card to which the transfer is to be effected, such piece of paper or card having been previously moistened with water, and I press the print and mount strongly together ”

“ Almost all the methods which have been proposed for the production of such pictures depend upon one principle. They are based on the fact that light renders certain soluble bodies insoluble in the usual menstrua. ”