Chapter 19

Deleschamps.—Glyphogen.Acetate of Silver8parts.Rectified Spirits500parts.Distilled Water500parts.Pure Nitric Acid260parts.Nitric Ether64parts.Oxalic Acid4parts.

This is recommended as being free from the defects of many of the other mordants, and as giving a clean vertical bite.

Several formulæ contain salts of copper.

Roret.Nitric Acid62parts.Distilled Water125parts.Alcohol187parts.Nitrate of Copper8parts.

Iodine is recommended as a very efficient mordant for steel, being free from the inconveniences caused by the disengagement of gas, as when biting with nitric acid. Messrs. Schwarz and Boehme give the following:

Iodine2parts.Iodide of Potassium5parts.Water40parts.

This may be further diluted up to 40 parts more water, for etching the finest lines. It gives good deep lines, sharp, and with clear edges even, for the finest and closely ruled lines have no tendency to run one into the other.

The following resembles the etching fluids for copper, commonly known as “Dutch mordant.”

Cooley.Hydrochloric Acid5parts.Water95parts.Mix and add:Chlorate of Potash1part.Water50parts.

Mix and add:

Cooley.—For electric etching with the battery, a solution of common salt is used.

II.MORDANTSFORCOPPER.—The most useful mordants for copper are nitric and nitrous acids, more or less diluted with water. Latterly, however, a mixture of chlorate of potash and hydrochloric acid, known as the “Dutch mordant,” has come more into use. For some purposes, perchloride of iron in solution is a useful mordant, particularly in photographic work with gelatine films. These two latter mordants bite more quietly than the acids, so that the lines are not so much enlarged, and there is not the same risk of close lines running together and other inconveniences caused by the evolution of bubbles of gas.

Acid Mordants.—(Lalanne.)Nitric Acid, at 40°1part.Water1part.

With a little old etching solution added, or pieces of scrap copper.

Malaret.Nitric or Sulphuric Acid1part.Saturated Solution of Bichromate of Potash2parts.Water5parts.

Fizeau used for daguerrotype etching a mordant composed of nitric, nitrous, and hydrochloric acids.

Dutch Mordant.Fuming Muriatic Acid (specific gravity, 1.190)10parts.Water70parts.To this add a boiling solution ofChlorate of Potash2parts.Water20parts.

To this add a boiling solution of

This may be diluted with from 100 to 400 parts of water as required.

Perchloride of iron, more or less diluted in water, is, according to Hamerton, an excellent mordant. It bites deep and clear, without enlarging the line much, and there is no ebullition, as with nitric acid. It is particularly useful in photographic etching through gelatine, as the latter is insoluble in it.

In most cases the mordant is flowed over the plate, or kept moving on it in the same way as a photographic developer. Such mordants are generally used for finishing off and deepening the light tints, and are calledeau fortis à couler or à passer. The following formulæ are given:{113}

Roret.—(Abraham Rosse’s.)Strong White or Distilled Vinegar3litres.Sal Ammoniac180grammes.Common Salt180grammes.Pure Verdigris120grammes.

A little oxalic acid is sometimes added. The solids are ground up, and boiled in the vinegar. Acetic acid at 3°, or pyroligneous acid, may be used in place of vinegar, and, if too strong, more vinegar should be added.

The following, used by Callot and Piranesi, is similar and prepared in the same way:

Strong Vinegar8parts.Verdigris4parts.Sal Ammoniac4parts.Salt4parts.Alum1part.Water16parts.

For relief etching use only 10 parts of water.

For etching copper in relief, the following glyphogen is recommended by Deleschamps:

Nitrous Acid, at 30°2ounces.Acetate of Silver6drachms.Hydrated Nitric Ether16ounces.

The nitric ether is prepared by mixing two ounces each of nitric acid and alcohol, and, when the reaction commences, stopping it by adding eight ounces of distilled water.

Flour of sulphur mixed with oil forms a good composition for etching tints. It can be applied with a brush. For a flat tint, Hamerton says “Oil the plate liberally with olive oil, and blow flour of sulphur upon this.” The sulphur, if allowed to remain on the plate, will produce a flat tint, more or less deep in proportion to the time it remains.

Roret gives the following formula for tint etching:

Bay Salt2parts.Sal Ammoniac1parts.Verdigris1part.

These are pounded together, and the mixture kept in a bottle.{114}

When required for use, grind up a little in a glass with some syrup of old honey, so as to make a mixture which flows readily. It may be used with a brush like a color. It is used after the bitings of aquatint plates with acid, to give finish and vary the tints.

Fielding (for aquatint).Nitrous Acid1part.Water5parts.

For the strongest touches, nitrous acid and water, equal parts, applied with a feather or brush. No. 19 may also be used for this purpose, either with or without a little gum.

Hamman.—Dilute nitric acid at 12° (sp. gr. 1.09), mixed with:

Distilled Water12parts.Alcohol3parts.

This is said to give a grain in biting, so that the ordinary grained ground may be dispensed with.

Electric Etching.It has frequently been proposed to etch by means of electricity, and in some cases it may be an advantage to do so.

It has frequently been proposed to etch by means of electricity, and in some cases it may be an advantage to do so.

The copper plate to be engraved is attached to the positive pole of a suitable battery and placed as anode in a solution of sulphate of copper, or in water acidulated with sulphuric acid.

In suitable cases, different degrees of depth may be given, putting parts of the anode and cathode nearer together or further apart.

Grove etched daguerrotype plates with a single pair of Grove or Bunsen cells, by inserting the plate to be etched, and a platinum plate of the same size, in a wooden frame having two grooves a quarter of an inch apart.

The daguerrotype having been attached to the battery as anode, and the platinum plates as cathode, the frame is immersed in a suitable vessel filled with

Hydrochloric Acid2parts.Distilled Water1part.

Contact is made for about half a minute, after which the plate is removed from the acid, washed thoroughly with distilled water, then placed in a solution of hyposulphite of soda or ammonia, and the deposit removed from the surface{115}with gentle rubbing with cotton. It is again rinsed with distilled water and dried.

MORDANTS FOR ZINC.The comparative cheapness of zinc would give it an advantage over copper or steel for engraving or etching with the graver or point, but it does not seem to be recommended for these purposes. It is hard to cut with the graver, and, though it bites easily, it is not suitable for fine work. Another defect is that it will not stand a long impression; but this may be overcome by surfacing the plate with copper. The principal uses of this metal for printing purposes are for surface printing or zincography in the same manner as lithography, and for the process of biting in relief, and zinco-typography or Gillotage, now so largely employed as a substitute for wood blocks. It can also be engraved very delicately in the same style as engraving is done on stone, through a coating of gum.

The comparative cheapness of zinc would give it an advantage over copper or steel for engraving or etching with the graver or point, but it does not seem to be recommended for these purposes. It is hard to cut with the graver, and, though it bites easily, it is not suitable for fine work. Another defect is that it will not stand a long impression; but this may be overcome by surfacing the plate with copper. The principal uses of this metal for printing purposes are for surface printing or zincography in the same manner as lithography, and for the process of biting in relief, and zinco-typography or Gillotage, now so largely employed as a substitute for wood blocks. It can also be engraved very delicately in the same style as engraving is done on stone, through a coating of gum.

The etching fluids for zinc are of two entirely different kinds: first, mixtures of gum and weak acids used for preparing plates for zincographic printing in the lithographic press, or for preliminary inking preparatory to being bitten in relief by the Gillotage process; and secondly, mineral acid, more or less dilute, used for biting in relief and ordinary etching.

Zincographic Etching.This kind of etching is more of a preparation of the plate for printing than engraving or biting, the object being merely to fill up the pores of the metal with gum, and prevent it receiving printers’ ink from the roller elsewhere than on the lines of the drawing.

This kind of etching is more of a preparation of the plate for printing than engraving or biting, the object being merely to fill up the pores of the metal with gum, and prevent it receiving printers’ ink from the roller elsewhere than on the lines of the drawing.

The solution most commonly employed for this purpose is a mixture of gum and decoction of nut-galls, in use at the Ordnance Survey Office, Southampton, and given by Sir Henry James in his work onPhoto-zincography. It is prepared as follows: Four ounces of Aleppo galls are bruised and steeped in three quarts of cold water for twenty-four hours; the water and galls are then boiled up together, and the decoction strained. The gum-water should be about the consistency of cream. One quart of the decoction of galls is added to three quarts of the gum-water and to the mixture are added about three ounces of phosphoric acid, which is prepared by placing sticks of phosphorus in a loosely corked bottle of water, so that the ends of the sticks may be uncovered. The oxidation of the phosphorus produces phosphoric acid, which dissolves as fast as it is formed.{116}

The etching solution should only just mark a piece of plain zinc.

In Richmond’sGrammar of Lithographythe following modifications of this formula are given:

Decoction of Nutgalls3⁄4pint.Gum Water as thick as Cream1⁄4pint.Phosphoric Acid Solution3drachms.

Boil one and a quarter ounces of bruised nutgalls in one and a quarter pounds of water till reduced to one-third, strain, and add two drachms of nitric acid and four drops of acetic acid.

Richmond recommends, however, the use of a simple decoction of galls without acid, and gumming in after etching.

Scamoni has the following, by Garnier: Boil about one and a half ounces of bruised gall-nuts in a pint of water till reduced to one-third, filter, and add two drops of nitric acid, and three or four drops of muriatic acid. For very fine work this may be weakened with water. It is applied for about a minute, then washed off, and the plate gummed.

Zinco-typographic Etching.In biting zinc plates in relief, the acid generally used is nitric of different degrees of strength, according to the nature and state of the work.

In biting zinc plates in relief, the acid generally used is nitric of different degrees of strength, according to the nature and state of the work.

After the transfer is made, the plate is etched with one of the foregoing preparations, then inked in and dusted with finely powdered resin, which adheres only to the lines. This procedure is followed after every biting, the plate being warmed to melt the resin and inky coating, so that it may run down between the lines and protect them from the undercutting action of the acid.

Kruger, in hisDie Zinkogravure, recommends for the first relief etching, nitric acid 30 to 40 drops to 100 grammes of water, applied for five minutes. For each subsequent etching, 8 to 10 drops of acid are added for each 100 grammes of water, and the time is increased, from five to fifteen minutes. For the final etching of the broad lights he uses:

Muriatic Acid4parts.Nitric acid1part.Water16parts.

To soften down the ridges between the lines the plate is inked and dusted as before, and etched with dilute nitric acid at five per cent., applied for a{117}minute, and the inking, dusting, and etching repeated as often as may be necessary.

THE DIFFERENCE.Finally, in this department, only the novice will require an explanation of the varied productions possible by means of the processes already given. As actual examples, reference may be had to the illustrations in this work. Figures 1, 2, and 3 are specimens of line work, zinc etchings made from pen and ink drawings. The figures in the following chapter were made in the same way.

Finally, in this department, only the novice will require an explanation of the varied productions possible by means of the processes already given. As actual examples, reference may be had to the illustrations in this work. Figures 1, 2, and 3 are specimens of line work, zinc etchings made from pen and ink drawings. The figures in the following chapter were made in the same way.

Fig. 13.

Fig. 14.

Figures 4, 5, 6, and 7, as well as some others, are zinc etchings reproduced from Mr. Mörch’s work. With them more effort has been made to secure half-tone by a variety and quantity, or filling, in of lines. The example below was made by using the objects (ferns) themselves as the negative, without any interposition from photography, and shows one of the possible applications of zinc etching. It is delicate work and is very beautiful when carefully done. An example of true half-tone, obtained in the manner described in Part II., is the one which follows. It was made by Mr. F. E. Ives, the earliest inventor of a half-tone process, several years ago. The larger examples of half-tone work which appear in this book are made after the most modern fashion and formulæ, as described in Part II., and will serve well to show what the worker in this fascinating process may expect to reach after patient and persistent experiment. When we look upon Fig. 1 and see the very best that zinc{118}etching could do a few years ago, and compare it with the Mosstype and other half-tone pictures now possible, we may well wonder at the growth of the art.

It has been attained by the careful and persistent plodding of a few. Many a method has been discarded for a newcomer, and there is no telling what may come next. Photography has about revolutionized the illustration of books and magazines, and has made the newspaper far more attractive than it was a few years ago. It has made the faces of almost every renowned individual familiar in every land and in every household, and the attractions of every known country have been so pictured by it that every intelligent child is familiar with them. It has been said that process-engraving has supplanted wood-engraving. This is not so. How many newspapers were illustrated before process-engraving was made available? How many works of the old masters and gems of the old museums abroad were made familiar to the lovers of pictures everywhere, by wood-engraving? Instead of coming into the arts to take the place of another, photo-engraving has made a place for itself and a market for itself. Moreover, it is refining and educating the masses by creating a love for art, where before its advent, there was very little feeling for the beautiful. Its accomplishments have been marvellous, and yet they have hardly begun. The good photography has done in bringing the wood-engraver up to his duty in following the artist in every line and light and shade, it will augment by teaching him how to secure the loveliest effects of nature. It will make way for more wood-engraving as well as for more process-pictures if you choose to call them such.

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