Photoengraving

“ Technically, however, "photo-intaglio" means a halftone engraving, the design of which is etched into the plate, leaving the ground (i.e., the whites) of the picture on the surface, instead of in relief with the whites etched down below the surface. The term "photogravure" is applied to a similar engraving in which the effects of light and shade are produced not by dots and stipples produced through a halftone screen, but by variations in depth of the depressions in the form of grain. ”

“ By what is known as photogravure, every tiny brush mark and every different tint of color is reproduced with scientific accuracy in black and white. This is accomplished by having a photograph of the painting taken on a gelatine film, which is suspended in a bath of acid in the line of an electric current. This current, playing over a sheet of copper, sets free the molecules of metal that are deposited upon the film, and filling all the little inequalities of the surface, produce what is practically a cast of the photograph in copper. ”

“ PHOTO-ENGRAVING. Photo-engravings are produced by means of photography. It is a fact worthy of note that experiments in photographic engraving gave rise to photography itself. The aim of Nicéphore Niepce, when he began his researches in 1813, was not only to fix the image obtained by the camera obscura on a plate of metal, but to convert this plate into an engraving which could be used on a printing-press. His early death prevented his perfecting the process to which he had devoted much time and study. ”

“ Photogravure is particularly suitable for the reproduction of drawings showing a large amount of detail and made up of a variety of tones rather than lines or stipple.
The photographic part of the process is essentially the same as making a carbon print from a photographic negative. This consists in exposing under the negative the carbon tissue, which is a mixture of gelatine, in which is dissolved bichromate of potash, and a suitable pigment. Such a film of bichromate gelatine is, when dry, sensitive to light. If no light gains access to it, the gelatine is readily soluble in warm water ”

“ He settled in Birmingham, where in 1864, while experimenting with carbon printing, he conceived a new mode of photographic engraving. The difficulties to be surmounted were very great, but on 5 Dec. 1865 he was enabled to demonstrate and exhibit examples of the beautiful mechanical process that bears his name to the Photographic Society. The main feature of the invention, patented on 24 July 1866 and called the Woodburytype, is that a photograph in gelatine is caused by enormous pressure to indent a sheet of lead. When perfected the invention came into common use, both in Europe and America. ”

“ The life of a photogravure plate without steel facing does not last much beyond 75 impressions, so that if an edition is needed, send the plate to any good printer who will have it steel-faced for you; their charges are very moderate, about 50 cents for a 4 × 6 plate. The steel-facing is accomplished by first making the plate chemically clean, as before preparation for graining, only be very thorough in using an old tooth-brush to get out the dirt and in addition use chloroform before using potash. Then solder a copper wire on to the back. The negative wire is attached to the copper plate. ”

“ Zinc etching is the simplest method of photo-engraving and should be thoroughly understood before one begins to inquire into the intricacies of the half-tone process. It is used to reproduce what is known as "black and white" work, or line drawings. Any drawing or print having black lines or dots on a white background, without any middle shades, may be engraved by this process. The old-fashioned "wet-plate" photography is used in making practically all process plates, either in line or half-tone. ”

“ Four baths are used, each of different strengths, the strongest is used first, the weakest last. I quote from the catalogue of the Boston Art Museum, of the exhibition illustrating the technical methods of the Reproductive Arts and Photo-Mechanical Processes, held January 8, 1892: "Photo-aquatint (photogravure) for the production of half-tone intaglio plates from photographs from nature, paintings, etc. A dry aquatint ground is laid on a metal plate, and over this is mounted a gelatine negative film, made by the pigment printing process. ”

“ The steel or zinc plate is then to be exposed to light to completely harden the mixture all over, and is then treated exactly as in my other engraving process; that is, pressed into soft metal by hydraulic pressure, electrotyped, and then the surface is aciercised or coated with steel. The dark parts are thus represented by a coarse grain, the middle tints by a medium grain, and the finest shades by the most infinitesimal particles, thus meeting all requirements necessary to a successful photo engraving process. ”

“ But everywhere the perseverance of zeal and talent is unfortunately insufficient to overcome the prejudices of the public, and its exaggerated confidence in the benefits of mechanical discovery.
Since the progress accomplished by science in the domain of heliographic reproduction, since the advantages with regard to material exactness that photography and the processes derived from it have offered, or seem to offer, line engraving, of all the different methods, is certainly the one that has suffered most from the supposed rivalry. ”

“ In fact, in the latter part of this work, a process is described for etching and taking printed impressions from Daguerreotype plates. As yet this process has produced no decided beneficial results--but future experiments may accomplish some practical discovery of intrinsic value to the art of engraving.
A very simple experiment will prove how essential light is to the coloring of the various species comprising the vegetable and animal kingdoms. If we transplant any shrub from the light of day into a dark cellar, we will soon see it lose its bright green color, and become perfectly white. ”

“ When we want reproductions from photographs we have a photo-engraving department where by means of a very powerful electric light we can reproduce pictures of all sorts; pen-drawings, facsimiles of old prints, photographs, and every variety of picture imaginable. These are developed on a sheet of metal instead of on a glass plate and then reproduced."
"That is the way you get the fine picture [174] sheets that you enjoy so much, Paul," put in Mr. Wright.
"The photo-engraving took the place of the woodcut," Mr. Hawley explained. ”

“ I tell you— (dogmatically, if you like to call it so, knowing it well) —a square inch of man's engraving is worth all the photographs that ever were dipped in acid (or left half-washed afterwards, which is saying much) —only it must be man's engraving; not machine's engraving. You have founded a school on patience and labor—only. That school must soon be extinct. You will have to found one on thought, which is Phœnician in immortality and fears no fire. Believe me, photography can do against line engraving just what Madame Tussaud's wax-work can do against sculpture. ”

“ PHOTO-ENGRAVING, ETCHING, AND LITHOGRAPHY. PART I. PHOTO-ENGRAVING IN LINE. CHAPTER I. APPLIANCES FOR MAKING PHOTOGRAPHIC NEGATIVES.
For all methods of heliographic printing a suitable photographic negative is absolutely necessary, and to produce that negative good apparatus and pure chemicals, used with skill and intelligence, are indispensable.
The studio must be well lighted, with a perfectly firm floor. The dark-room should be kept for negative work only (the room where the zinc printing is carried on being a separate room) . ”

“ Photography is the basis of all the mechanical processes that come under the general head of photo-engraving. These processes are generally called mechanical, yet, as in photography, great skill is required to produce the best results. The higher grades of half-tone work require much careful finishing, which is all done by hand, and which, moreover, must be done by a skilful, intelligent, and artistic engraver. Practically all things may be reproduced successfully by photo-engraving, but the vast majority of subjects that go to the photo-engraver are either photographs or drawings. ”

“ A photo print can be made direct on the zinc or aluminium plate, and by a slight modification of the photo-engraving process it can be developed according to lithographic methods.
It is impossible to introduce an intermediate process without, in some manner at least, depreciating the quality of the work. In a direct photo print on zinc, or, in fact, on any suitable printing surface, the finer qualities of the work are much more likely to be retained than when a transfer print is made under the negative and afterwards transferred in the usual manner. ”

“ The shading on a drawing to be photo-engraved must be produced by lines, and not by tints, for tints, whether of black or of colors, will not photo-engrave properly.
It is generally preferred to make the drawing for a photo-engraving larger than the engraving that is to be made from it, a good proportion being to make the drawing twice the length the engraving is to be. This serves to reduce the magnitude of any roughness in the lines of the drawing, and, therefore, to make the engraving better than the drawing. ”

“ The tones are formed by scraping away the ink by the engraver, the highest light being the deepest. It gives a very good tonality, and is really the only rival to photo-etching, but the plate will not last well, thirty good prints often being all that can be taken from a plate. The engraver, too, has not sufficient control over his work. As a rule it is only used for fac-simile work, and not for original work. It will in our opinion be the last form of engraving to succumb to photo-etching. It is better suited for portraiture than landscape work ”

“ The block must also be made ready, not by putting cut-outs on the tympan or cylinder, but underneath the block, and there as thin as possible.
The ink must be good and not too thin; the rollers must be free from flaws and not too tacky. In fact, as much care is required on the press as during the photographic and subsequent operations. Indeed photo-engraving and zinc etching would have come into popular use more rapidly than they have, if printers had been willing to give them the special “making-ready” attention they require. ”

“ This description of drawing is applicable to wood engraving, to line engraving upon copper or steel, as well as to all the methods for automatically producing blocks for relief printing. The line method is also universally adopted by etchers in intaglio.
Successfully to prepare drawings for photographic reproduction it is essential that some knowledge should be possessed of the fundamental principles of {95} photography, as well as an acquaintance with the capabilities of the particular process of production which is to be employed. ”

“ Drawings made on scraper boards, grained papers, or by the aid of shading mediums, are photographed and reproduced by the ordinary line method. In making sketches for “half-tone” photo-mechanical reproduction it must be remembered that, as far as photo-lithography is concerned, it is impossible to accentuate effects by what is known as “fine etching” when applied to photo-engraving. A negative for photo-process work of any description should be absolutely perfect in every respect. ”

“ The Scovill Printing Frames for Photo-Engraving.
The Printing Frames made by the American Optical Co. for photo-engraving are like everything else manufactured by this factory, of the highest degree of perfection, and the utmost care was given to the comparative distance of screws so as to produce an even pressure. Many negatives have been either ruined or snapped by the use of imperfect Printing Frames.
The American Optical Co. Printing Frames for photo-engraving are the only safe ones on the market.
PRICES.
Larger and special sizes made to order. ”

“ For this reason photography is used not only in astronomy but in many other branches of science, among its most important uses being the making of records of microscopic objects.
A device carrying a photographic plate is attached to the eye-piece of a microscope; the plate being exposed affords, on development, a precise record of the subject under observation. It may be noted that in this case, as in astronomical photography, no camera lens is required; the microscope, like the telescope, projects an aërial image which is impressed on the plate. ”

“ As everyone acquainted with photography knows, a picture is made ordinarily by exposing a sensitized plate or film, developing the latter to make a negative, then exposing sensitive print paper to the light that comes through the negative, thus reversing the lights and shadows and creating a positive in the exact semblance of the subject photographed. A concern in Cleveland, Ohio, the Positype Co., produced Bromotype paper which could be exposed directly in the camera, coming out of the developing process as a positive without the intervention of a film or plate negative. ”

“ In sensitising the receiving paper, glass, or metal with such a compound it must necessarily be protected from exposure to sunlight, and this fact, together with the desire to sensitise the image produced by the camera, not only suggested but seemed to render that instrument indispensable to photography. Nevertheless the experiments of chemists fell short of the high mark, and it was reserved for an artist to unite the efforts of the sun and the chemists in a successful instrument. ”