Practical guide to photographic & photo-mechanical printing

Preface

I have to acknowledge the assistance of many who have aided me in getting the information necessary for the preparation of this book. I have freely made use of all kinds of publications on photographic matters in my efforts to acquire a practical acquaintance with processes. Wherever I can tell whence my knowledge has come I do so, but it is possible that in some cases I have not done so. With most of the processes described I have been familiar for some time. With others, whenever possible, I have recently made myself practically familiar, and when one has become familiar with a process he is liable to forget whence his knowledge came. If, therefore, I have sinned in not acknowledging sources of information when I should have acknowledged them, I have sinned unwittingly.

I must make special mention of one friend who has helped me more than others. The most difficult part of my task has been to get a knowledge of photo-mechanical processes. Here I have been most mate-

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PREFACE rially aided by T. Bolas. His lectures on the subject before the Society of Arts I have, of course, made free use of — they constituting the standard work on photo-mechanical printing in England ; but further than that, I have found Bolas ever ready personally to help me to overcome difficulties, to discover causes of defects, etc. In fact, his wide knowledge of the subject has been always at my command, requiring merely to be drawn on.

Engineering College,

Imperial University, Tokio, Japan,

Introduction

The term “ Photographic Printing ” might, with propriety, be applied to any and every process for obtaining a positive photograph from a negative, — that is to say, for obtaining a picture with the gradations of light and shade somewhat as they are seen in nature, from one in which their values are reversed, the light shades being represented as dark portions of the image, the dark as light.

It is usual, however, to confine the term to such processes as are applicable to a flexible support, generally paper, but sometimes cloth or other fabrics.

It is the writer’s intention to use the term chiefly in this partially restricted sense, taking into consideration all processes which are actually practised for producing positives on paper, cloth, etc., but not leaving entirely out of consideration those for producing positives (commonly called transparencies) on glass, on china, and so forth.

The object of this work is to give practical instructions in the working of all processes which are in actual everyday use at this date, and the author’s attempt will be to make such instructions of so full a nature, that they may serve as a guide to any one who may wish actually to

INTRODUCTION viii

practise the processes. To make the work complete, processes which have at one time been popular, but which have been superseded by others, will be described ; but more briefly than those which are now actually used, the interest attaching to defunct processes being really little more than historical.

In the cases of the most popular processes the chemical reactions will be briefly discussed, but the writer will avoid technical language as much as possible. He will also avoid all treatment of the purely artistic side of photographic printing, aiming to give such instructions only as may lead to that technical excellence which is one of the necessities of artistic work.

Chap. I. Historical Sketch of Photographic Printing Processes. — Processes before that of Daguerre — The Daguerreotype — Talbot’s process — Toning of prints — Albumen used in printing— The carbon process — Uranium salts in printing — The platinotype process — The “blue process” — Processes requiring but short exposures, and suitable to direct enlarging — Gelatino- bromide printing — Gelatino - chloride processes

Chap. II. Historical Sketch of Photo - Mechanical Printing Processes. — The Woodbury -type process — Ordinary engraving processes — Yery early photo-engraving processes — Fox Talbot’s photo - engraving processes — Modern photo-engraving processes — The Woodbury photo-engraving process — Klie’s process — Waterhouse’s process — Obernetter’s photo-engraving process — Photo-lithographic processes, etc. — Surface-printing processes, — The Lichtdriick or collotype process — Type-block processes — The Pretch process — Meisenbach’s process — Woodbury block process — Ives’s process — Zuccato’s process — The reproduction of line subjects .......

fixing, etc. of paper sensitised on a neutral bath . . 80

Chap. XI. Silver Printing ( continued ). — Storing paper prepared on a neutral bath, fuming, etc 83

Chap. XII. Silver Printing ( continued ). — Printing on plain

Chap. XIII. Silver Printing {continued). — Various toning Formulae ; general remarks on toning — Toning and fixing in one bath — Tbe sel d'or or toning process — Tbe acetate bath — The gold and phosphate toning bath — The bicarbonate toning bath — General remarks on toning . 93

Chap. XIV. Silver Printing {continued). — On the chemistry of the image of silver prints — To determine the quantity of chloride present in a sheet of albumenised paper . . 103

Chap. XV. Various Manipulations of Contact Printing.

— Treatment of the negative before printing and during printing ; treatment of paper to suit certain negatives —

The negative is too thin — The negative is too dense, giving prints which are hard — Local modifications of the negative xi

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Chap. XVI. Various Manipulations of Contact Printing

{continued). — Cutting the paper — Cutting up paper . . 120

Chap. XVII. Various Manipulations of Contact Printing (i continued ). — Vignetting — Reversed vignettes — Vignettes with tinted margins . 125

Chap. XVIII. Various Manipulations of Contact Printing ( continued ). — Skies ; composition printing — Composition printing ......... 136

Chap. XIX. Silver Printing. — Gelatino-bromide of silver for printing ; direct enlarging — Contact printing with gelatino-bromide paper — Development — Fixing the prints — Pyro-developer for bromide paper — Stock solution —

Warm tones with gelatino-bromide paper — Vignetting gelatino - bromide prints — Direct enlargement on gelatino - bromide paper — Vignetting direct enlargements 146

Chap. XX. Silver Printing {continued). — “Rapid” printing process — Exposure of the paper — Developing the prints —

Toning the prints — Fixing the prints . . . . 158

Chap. XXI. Silver Printing {continued). — Gelatino-chloride papers for printing out — Manipulation of gelatino-chloride paper— The manufacture of gelatino-chloride emulsion for printing out — (1) Chloride of silver emulsion — (2) Citrate of silver emulsion 164

Chap. XXII. Silver Printing {continued). — Defects in silver prints and their remedies — The prints refuse to tone — The prints tone, hut the tone is more or less lost in subsequent operations — The prints tone unevenly — The high lights of the prints are yellow, not white as they should be — The • prints lack contrast — The shadows are heavy and lacking in detail — Bronzing of prints — The prints are mealy —

Marks of various kinds on the prints .... 172 xii

Chap. XXIII. Silver Printing ( continued ). — The treatment of residues — Disposal of the residues — To convert the silver got from residues into a printing bath — To precipitate and redissolve an old sensitising bath

Chap. XXIY. The Carbon Processes. — The powder or dusting -on process — The powder — The glass — The sensi tive mixture — The transparency — Preparing the plate — The exposure — Development of the image — Fixing the image — Defects in powder pictures — The powder process for intensifying negatives and for producing reversed negatives ...

Chap. XXY. The Carbon Processes {continued). — The single transfer pigment process — The tissue — Preparations of the negative and exposure of the tissue — The development — Fixing the print — Under and over exposure — The continuing action of light .......

Chap. XXYI. The Carbon Processes ( continued ). — The double transfer process — Rigid supports — Flexible supports

Chap. XXYII. The Carbon Processes {continued). — Lambert type ; transparencies, lantern slides, opals, etc., in carbon — Transparencies in carbon — Opalotypes

Chap. XXYIII. The Carbon Processes {continued). — Sensitising tissue — Strong and weak sensitising baths ; to print from over- thin and over-dense negatives — To intensify prints .........

Chap. XXIX. The Carbon Processes {continued). — The manufacture of tissue — Coating the paper with sensitive compound

Chap. XXX. The Carbon Processes {continued). — Defects and remedies in pigment prints — Frilling of the film — Reticulation of the film — Streaks and spots in the prints — The prints are too dark — The prints are too light — The print developed on collodionised glass refuses to leave the support ........

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Chap. XXXI. The Platinotype Process. — Exposure of the paper — Development of the image — Fixing and washing the prints — Brown tones in platinotype — Sensitising of paper — Platinotype prints on linen and other fabrics

Chap. XXXII. Mounting Prints. — Mounting albumenised paper prints, platinotype prints, etc., in the ordinary way — Dry mounting — Rolling and burnishing prints — Encaustic paste — Mounting prints that have been dried in optical contact with glass — Enamelling prints — Mounting prints in optical contact with glass for rims, etc.

Photo-Mechanical Printing Processes. — Preliminary note

Chap. XXXIII. Photo-Mechanical Printing Processes. — The Woodbury - type process — Preparing the sensitive tissue — The exposure — Development of the image — Production of lead moulds from Woodbury reliefs

Chap. XXXI Y. Photo -Mechanical Printing Processes ( continued ). — Stannotype — The transparency — The relief or mould — Printing from Woodbury and Stannotype reliefs

Chap. XXXY. Photo - Mechanical Printing Processes {continued). — Photo-lithography — Lithographic transfers — Photographic transfers from line subjects — Photo-zincography— Photo-lithography in half-tone ....

Chap. XXXYI. Photo -Mechanical Printing Processes {continued). — Collotype — Preparation of collotype plates — The Albert-type — Husnik’s process — Exposure of the plates — Development of the plate — Printing from the plate — Printing by machine — The heliotype process

Chap. XXXYII. Photo - Mechanical Printing Processes {continued). — Etching transfers on zinc to produce relief blocks — Materials for etching ......

Chap. XXXYIII. Photo-Mechanical Printing Processes {continued). — The asphalt process for the production of xiii

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254 264

XIV line relief blocks — Preparation of the bitumen varnish — Coating the plates — Exposure and development of the plates — Etching the plate ......

Chap. XXXIX. Photo -Mechanical Printing Processes (i continued ). — Other methods of producing line relief blocks — The “instantaneous asphalt process” — Processes of casting from gelatine reliefs .....

Chap. XL. Photo - Mechanical Printing Processes ( continued)., — Processes for producing entaglio or engraved line plates .

Chap. XLI. Photo -Mechanical Printing Processes {continued).— Half-tone processes

Chap. XLI I. Photo-Mechanical Printing Processes {continued).— Methods of obtaining half-tone in photo -lithography— Transfer from collotype plate — Description of Husband’s papyrotint process

Chap. XLIII. Photo-Mechanical Printing Processes {continued).— Methods of obtaining half-tone in phototype blocks — The use of a grained screen for producing a half-tone type-block — Woodbury process — Process of Ives and analagous processes .......

Chap. XLIY. Photo-Mechanical Printing Processes {continued).— Methods of obtaining half-tone in entaglio plates — Woodbury’s process — Klie’s process — The Waterhouse process — Sawyer’s process — Obernetter’s process

Chap. XLV. The Production of Transparencies or Transparent Positives

Chap. XLVI. Processes for Copying Plans or other Drawings in Blue. — The ordinary “blue process” — Blue positive processes .

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Chapter I Historical Sketch Of Photographic Printing Processes

Processes before that of Daguerre

All the photographic processes, before that which bears the name of Daguerreotype, appear to have been negative processes. The lighter shades of nature being shown as blacks, the darker shades as whites.

To Nicephore de Niepce is due, so far as is known, the credit of producing the first photograph in the sense of a camera picture. Niepce had been for several years at work experimenting with various substances, but it was not before 1827 that he produced anything which could be called at all successful. Even then it was negatives only that he produced1— a fact greatly in favour of his process, had the thought struck him to use his results as a means to an end, but not as pictures themselves. The idea does not appear to have struck him, however, or, if it did, he was unable to work it out, for we find him, in his correspond-

1 It is only fair to say here that Niepce described a method whereby he proposed to turn his negatives into positives — not to reproduce positives from them. This was by the use of fumes of iodine to darken the parts of his silver plate not covered with bitumen. I can scarcely imagine that the method was efficient for the purpose indicated ; but it seems quite possible that the use of iodine, as described by Niepce, laid the foundation of the iodide of silver process for which Daguerre commonly gets all the credit.

B ence, describing attempts he is making to get positives directly in the camera. This was first done, or at any rate the means of doing it was first published, in 1839 by Daguerre, who took all the credit to himself of the invention of the process, known as Daguerreotype, although it is becoming more apparent, the more the subject is investigated, that the credit was really due, at any rate in great measure, to Niepce, who had entered into a partnership with Daguerre, but who died before the results of their joint investigations were published.

The Daguerreotype

The Daguerreotype was a positive process. The image produced in the camera was a positive, and, therefore, there was no need to print from it, even had it been possible to do so.

Talbot’s Process

But almost at the very same time that Daguerre published the Daguerreotype process, — one month before, in fact, — Fox Talbot in this country announced the invention of a negative process on paper. This was in 1839, but I can find no mention of any attempt to print or produce positives from the negatives till 1842, when Fox Talbot, in patenting his well-known calotype process, — a second and improved negative process, — mentions its applicability to the obtaining of positive copies from negatives. It is probable, however, that Talbot had used his original paper process, which was certainly far better suited to the purpose, for the production of prints. In this first process chloride of silver was formed on paper, and chloride of silver on such a support forms an excellent film for positive prints, in fact, it constitutes a process for printing used at times even to this day, and is probably a better process than some that have almost entirely replaced it. Fox Talbot’s second process, in which iodide of silver is used, is not nearly so applicable to the production of pleasing prints.

It is pretty certain that the earliest prints that are still preserved, actually produced by Fox Talbot, are on paper which had been treated with chloride of silver. Some of these still remain in a very perfect state of preservation.

Toning of Prints

At a very early date in the history of silver printing it was observed that the colour of the prints, as they came from the hyposulphite bath used for fixing — that is to say, for the removal of the chloride of silver not acted on by light — varied, some being of a much more pleasing colour than others. It was found that the bath, after it had been kept for some time, gave deeper, darker coloured prints than when fresh. It was soon surmised that the darker colours with the older solution was due to the silver salts dissolved from the paper, and silver chloride was afterwards added to the hyposulphite bath for the express purpose of giving the dark colour, of toning, in fact, this being the first toning process that we have any record of.

Gold, in the form of chloride, was subsequently used, first in an acid solution, afterwards mixed with the fixingbath, then in the “ set d’or ” bath which contained only a small quantity of hyposulphite, and was used before the fixing bath, and finally in an alkaline solution before or after fixing.

Albumen used in Printing

The introduction of albumen was brought about, at a very early date, from the desire to keep the sensitive salts of silver as much as possible on the surface of the paper. The idea of the very high gloss now common did not suggest itself. In fact, in the older prints on albumenised paper there is to be seen no gloss at all, they are only distinguishable from prints on plain paper by the somewhat finer detail that is to be seen. The gloss was a thing that came by degrees as the manufacturers improved their means of production. The gloss is considered by many, however, to be the reverse of an improvement.

I have indicated the steps whereby the printing process, which, in spite of all opposition, is the favourite process at this present day, has arisen. The results obtained by its aid leave but little to he desired in the way of beauty of colour and delicacy of detail, but, alas ! there is a terrible drawback to the process — the results are not permanent. It was not long after the very first prints were produced by Talbot that he observed that time had the effect of causing them to fade. Since the time mentioned much has been done to improve the permanency of prints by the favourite albumen process ; and there are to be found good authorities who do not hesitate to say that, with our present knowledge, a print on albumenised paper may be as permanent as the paper itself, if due precautions be taken.

Whether this be so or not, the fact remains that since doubt was first thrown on the permanency of silver prints, experimentalists directed their attention to the working out of a process which should be undoubtedly permanent, in which the image should be formed of some substance which was known not to be subject to change.

The Carbon Process

The first process which really successfully fulfilled these conditions was the carbon process of Swan, in which the image was produced of carbon in a very fine state of division, held in suspension by gelatine. There were, however, various steps leading up to the process of Swan.

As early as 1839, Mungo Ponton published the fact that in certain conditions bichromate of potash is sensitive to light ; or, to speak more correctly, may form compounds or mixtures which are sensible to light. Thus he found that on soaking a sheet of paper with a solution of the salt, drying it in the dark, and afterwards placing it in bright light under an engraving, he got a faint yellow picture on an orange ground, which could be finer by simply washing it in water. This discovery formed the germ of the present carbon process, which is perhaps now the best known of all processes for producing permanent prints. It was subsequently discovered that various organic substances, such as gelatine, gum, starch, etc., were rendered sensitive by bichromate of potash, in the sense that when treated with it in solution, dried, and afterwards exposed to light, they were rendered insoluble in water. This was a great step, for it now became evident to Poitevin and others that there lay in this fact the potentiality of a practicable printing process, inasmuch as, by exposing under a negative, paper treated with, for example, gelatine, to which had been applied a solution of bichromate of potash, some parts (those which had been acted on by light) would be rendered insoluble, whilst others (those protected by the high lights, or dense parts of the negative), would remain soluble, and further, inasmuch as the soluble portion of the gelatine might afterwards be washed away with hot water.

Various attempts failed, on account of the impossibility of getting “ half-tone.” Where the gelatine was rendered quite insoluble, as in the deepest shadows, it was all right, and the same was the case where it was left quite soluble, as in the highest lights. But in the half-tones the film consists of a surface of insoluble gelatine, with soluble gelatine behind, the soluble protected by the insoluble from the action of the hot water, used for development, and either failing to be dissolved by the water, or if dissolved, carrying away with it the insoluble outer surface, which should have remained to form the half-tone.

J. C. Burnett, in 1868, got over the difficulty by the ingenious device of printing through the paper supporting the film of gelatine. By this arrangement all the gelatine rendered insoluble was next to the paper, whilst that left soluble was on the outer surface, and could readily be washed away.

There are, however, obvious objections to printing through the paper, one being the additional length of time involved, another being the liability that there is for any grain in the paper to show in the print. Burnett’s process was therefore superseded by Swan’s.

But whilst these various experimenters were working towards the process of Swan, which, to all intents and purposes, is the carbon process of the present day, a permanent process which, if restricted in its uses, was yet perfect, so far as it went, had been invented. Messrs. Gamier and Salmon, in 1858, described a process in which paper treated with citrate of iron, and exposed under a transparent positive, was brushed over with a dark powder, when a print was produced, the citrate of iron being naturally “ tacky,” and causing the adhesion of the powder, but being rendered hard and dry where acted upon by light, and in such parts not “ tacking ” any powder. The process, modified to a great extent, is slightly used at the present day under the name of the “ Powder Process.”

J. W. Swan, in 1864, brought before the public what may be looked upon as really the first carbon process of any real value for practical printing. He produced what he called a “carbon tissue.” Gelatine was dissolved in water, in which also was dissolved bichromate of potash ; finally, carbon in a very fine state of division was introduced so as to form a “pigment.” Paper was then coated with the mixture, and was dried. It was afterwards exposed under negatives, an actinometer being used to time the exposure, as no visible image was produced. The print was now coated with a solution of rubber in benzine, and was cemented by passing it between rolls to a second rubber film. Warm water was applied till the gelatine next the paper (still soluble) was softened, when the paper could be stripped away, leaving only the gelatine, soluble and insoluble, with the pigment, etc. The insoluble gelatine was then washed away by the further application of warm water, till nothing but the image or picture was left. This image was now brought into contact with the paper intended to act as a final support, albumen being used to cause it to adhere ; and when the whole was dry, the application of benzine softened the rubber, and enabled the print to be stripped from the plate used for development.

The only improvement of any importance which has been made on the process of Swan arose from the discovery, by J. R. Johnson in 1869, that it is quite unnecessary to cement the undeveloped print out of the support used in development, for the reason that, if the tissue be placed in water, and be brought into contact with any waterproof support whilst the gelatine is still swelling, it (the tissue) will adhere firmly by atmospheric pressure.

It had been observed previously by Yogel that cement was not at all times necessary ; but he had not noticed that the only condition necessary to secure adhesion without cement was that the support be impermeable to water. Johnson used ridged supports, such as sheets of zinc and opal glasses, but Sawyer some time ago patented a “ flexible support,” consisting of paper rendered impermeable to water by treatment with varnishes.

The bichromate of potash is not always mixed with the gelatine before the paper is coated. A tissue prepared by coating paper with a mixture of gelatine, water, and colouring matter may be dried and put on one side. In this condition it will keep for a very long time, and it can be sensitised at any time by floating it on a solution of bichromate of potash in water.

Uranium Salts in Printing

A historical sketch of printing processes would be incomplete without some mention of the use of salts of uranium. These found very great favour with the photographic public some twenty years ago, one of the claims of the process being that it gave results very much more permanent than those on albumenised pajDer with silver. To how great an extent time has proved this theory to be correct I am unable to say. The process has now dropped entirely out of use ; so far as I know, no single photographer at this date producing prints by its means.

It was known in its most popular form under the title “ Wothly-type,” Wothly being the name of the inventor of a particular variety of the uranium process. He deserves, so far as I am aware, the credit of being the first to use collodion on paper for positive printing. Since his time collodion, holding in suspension chloride of silver, has been used as a film for positive printing with very good results.

Perhaps the process which most deserves notice after the carbon process of Swan is the platinotype process of Willis, patented in 1874, and now in general use.

In this process paper is coated with a ferric salt, and also with a salt of platinum. When the paper is exposed under a negative, the ferric salt is turned into a ferrous salt wherever it is acted upon by light. Now a fernms salt has the power when it is in solution to reduce a platinous salt to metallic platinum, and ferrous salts are soluble in oxalate of potash. It is therefore possible by floating a print of the kind described — the image in ferrous salt, on a solution of oxalate of potash — to develop an image in platinum-black, — that is to say, in metallic platinum, in a very fine state of division. The oxalate of potash dissolves the ferrous salt, which latter immediately reduces the platinous salt.

Platinotype prints are extremely delicate and beautiful in colour. They resemble in general appearance the very finest engravings, and it is claimed for them that they are absolutely permanent.

The “ Blue Process ”

An application of the action of the light on ferrous salts just explained has been made use of in a process much older than the platinotype. It is the well-known “ blue process ” used for the copying of plans, etc. It will be completely understood when I explain that ferricyanide of potassium takes the place of the salt of platinum in the platinotype process, and that ferri-cyanide of potassium forms a blue compound with a ferrous salt — in fact, forms Prussian blue. The compound is, however, formed without the necessity of dissolving the ferrous salt, and therefore 4he blue prints can be fixed in water only.

These blue prints have for the most part been used in copying plans, the prints showing white lines on a deep blue ground ; but quite recently the process has come somewhat into fashion for printing from a certain class of landscape negatives.

Processes requiring but short Exposures , and suitable to direct Enlarging

For the production of enlargements it has always been considered advisable to have a process more rapid than any of those just described, because, unless very expensive appliances with large lenses, etc., be fixed up, the time taken to enlarge with any ordinary printing out process is enormously long. Even with the solar, enlarging arrangement just referred to, the photographer is dependent on bright sunshine. It is of course unnecessary to say anything as to the uncertainty of his having it in this country.

When more than one enlargement is required, it is common to make an enlarged negative from which large prints are taken in the ordinary way, and this process is, as a rule, gone through even when only one print is wanted in any of the printing out processes ; but it has always been the desire of photographers, at least to be able to enlarge directly for some of their work without the intervention of a negative.

Iodide of silver on paper (the calotype process without the oiling of the paper) was much used, a comparatively brief exposure giving an image which could afterwards be developed. Afterwards “ collodion transfers,” as they were called, were very popular. These were simply transparencies on wet collodion films transferred from glass to paper.

Gelatino-Bromide Printing

Recently gelatino- bromide paper has been very much used for the purpose just indicated. I believe that Swan, the inventor of the carbon process already described, patented printing on paper coated with a gelatino-bromide emulsion as early as 1878. Certainly the first gelatino-bromide prints I ever saw were in his hands, and were shown in Edinburgh a little after that date.

It was not, however, till several years after the date just mentioned that gelatino-bromide became at all popular. Since its first commercial introduction, however, it has gained very rapidly in popularity, and now it is used very extensively both for direct enlargement and contact printing. Its makers claim permanence for it, and there can at any rate be no doubt that prints produced on it are far more permanent than those on its rival — sensitised albumenised paper.