Photo-engraving on zinc and copper in line and half tone and photo-lithography : a practical manual

Front matter

Photoengraving

AND

Photo -Lithography

Appendix

General Hints

Use of Gelatine Dry Plates in Photo Engraving Hints by Professor Scamoni Retouching Photo-Litho Transfers Zinc Plates coated with Carbonate of Lime ...

Method of strongly Etching a Stone Modern Photo-Lithography, by H. Butler Colas’ Black Process

A New Method of Photo Engraving, by J. R. Sawyer Obernetter’s Photo Engraving Process Klic’s Process for Intaglio Plates Asser’s Starch Process

Pretsch Process for making Photo Tint Blocks About Photo Lithography Silvering Glass Mirrors

Recent Improvements in the Asphalt Process...

The Velvet Roller and Collotype for Amateurs Photography and Newspaper

Various Mordants for etching on Steel, Zinc, Copper, &c.,

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PHOTO-ENGRA RING.

INTRODUCTION.

I1E subject of making Photographs applicable for the illustration of Letterpress, instead of wood cuts, has occupied the attention of experimentalists since the earliest days of the art-science, as the records of the Patent Office show ; but until the last few years, little or no progress has been made ; in fact until the advantages for cheap and quick productions of the process called Gillotage was demonstrated, very few examples of Phototype blocks offering encouragement to the practical printer were made.

This process of Gillotage was simply a Drawing in line made either direct upon zinc, or transfered to the zinc by ordinary Lithography, the drawing being made upon Litho. transfer paper.

This process answers admirably for original drawings by artists who can draw direct on zinc and work within a given space, but if the drawing has to be very small, or a block is required from a drawing already in existence, and that drawing too large for the contemplated block, then photography was brought in, and from the drawing a negative made the required size, from that negative a photo, litho. transfer printed upon paper coated with gelatine, coated (after exposure) with ink and then developed, this transfer was either laid direct upon the zinc or was first of all transfered to stone, then after touching up, a litho transfer was pulled which was laid down upon zinc and etched in relief.

The next step in progress was the process of printing from a photographic negative direct upon the zinc so securing firmer and better results than when one or two transfers had to be made.

Both these processes are only suitable for the production of .pictures in line, so that the printing of a photograph with its smooth gradations of half tones along with letterpress was still as far off as ever until iu 1882-83 when Meisenbach and Brown Barnes and Bell produced some results that fairly showed it was possible to bridge over the difficulties between photo-engraving in line aud half tone.

Meisenbach’s method of doing this is a secret process, and I will not attempt guessing at it, but that of Brown, Barnes and Bell is attained by embossing a paper photograph with a grain by passing it in contact with a wire gauze, sometimes inked and sometimes not, between powerful rollers, then from the photograph thus embossed a negative is made, from this negative a print in taken on zinc and etched into relief.

The grain thus embossed upon the paper print when photographed upon the zinc fills up the intervals between the lights and black and also binds the half tones, so that when etched a phototypic block in half tone capable of being printed with type is the result.

This process or method is patented 1883 and would not have been thus described but I find that as early as 1855 A. J. Berchtold took out a patent for producing grain by printing in black or any color from a plate or block or other printing surface, or by perforating or making strokes, lines, or dots by roller or other instruments, these perforations going through the photograph or only partly so.

Whilst upou this subject of giving a grain to the photograph for reproduction as a printing block it will be interesting to give the various methods patented at various times with dates.

Iu 1852 Mr. Fox Talbot in his patent for intaglio blocks described his method of producing a graiu by placing muslin, crape, &c., between the positive and sensitive surface or printed the grain first and then the picture. Pretsch 1854 obtained grain by the reticulation of gelatine.

J. W. Swan 1865 made a relief tissue containing charcoal or other inert grit. E. & J. Bullock 1865 published perhaps the most important specification aud described all or nearly of the practical methods of obtainiug grained photographs.

They placed any fine fabric between negative and sensitive surface, or interposed it between camera and object to be photographed, or copies of granulated or reticulated structures or fabrics upon glass &c., were used between negative and sensitive surface or between lens and prepared plate during exposure in the camera ; or such copy may be placed face to face with ordinary negative, both copied together, or by the superposition of grain upon prepared surface and printing image by aid of solar camera.

Since then many other patents have been taken out but the methods were more or less repetitions of the above. In 1879 J. W. Swan makes grained negatives by using a screen in front of sensitive plate and moves this screen during exposure and Meisenbach’s specification a little later is to the same end.

Woodbury reliefs can be used for the production of phototype blocks in a very simple manner, by embossing a piece of ordinary litho. transfer paper with lines, dots or stipple by contact with wire gauze or an engraved plate, then placing in contact with a relief thinly coated with transfer ink and then subjecting them to heavy pressure in type, litho. or hydraulic press, or instead of embossing the transfer paper the wire gauze or engraved plate is placed in bed of press then the litho transfer paper laid upon it (face up) and upon that the inked relief, then upon application of pressure a grained transfer is obtained which may be transferred to zinc and etched in relief.

And now having given full consideration to the theoretical we will now plunge into the practical.

As this treatise is written for those who are both (and neither) photographers and lithographers, it has been deemed the wisest and best course to treat each subject as far as required for the proper working of the processes described in this book in as elementary a manner as possible, so as to serve as a guide to the expert as well as to beginner. In order to simplify matters when treating of the different methods, all the different formula will be given once for all, and under each process reference will be made to the page and section.

CHAPTER I.

LIST OF APPARATUS &c REQUIRED.

Section I. — Photographic Negatives

HP HE studio and dark room it will be assumed, are either already built, or if to be built or converted, that most people as a rule will prefer their own model. I will content myself with saying that the studio must possess a floor that is perfectly steady and that the portion where the object to be photographed will be placed is well lighted with a good all round light, and the dark room is fitted with a sink in front of a good sized window covered with a non-actinic medium such as two thicknesses of golden fabric, so as to have plenty of light to see the progress of the developement of image and that there is plenty of bench room to hold the various baths, dishes, bottles &c.

The camera must be of the copying type with a long bellows and should not be less than 12 by 10, fitted with rackwork so as to be able to get absolute sharpness in focussing.

It will be a great advantage and aid in adjusting the position of the drawings to be copied on the focussing screen, if a line be drawn in the centre vertically and another horizontally so that they bisect each other exactly in centre, then from the centre mark and number each inch and 1 inch upon each of the four arms of the cross, it can then be seen at a glance not only that the picture is in the centre but also that it is about the right size.

The dark slide must be light-tight, and made for strength and not for portability.’

The lens should be of the rectilinear type and should be capable of covering the largest size plate the camera will take, quite sharp to the corners ; for a 12 by 10 plate a lens with an equivalent focus of about 18 inches will be best.

To the lens should be fitted a reversing mirror of silvered glass mounted behind the lens by preference, as such a style of mounting not only protects the surface of mirror from the air but keeps extraneous light from detracting from the brilliancy of the image.

The camera must be mounted upon a solid table stand fixed upon small grooved or flanged wheels, such wheels running either upon rails fixed upon or in grooves cut into the floor at right angles to the wall against which the copying board is fitted.

The copying easel is placed perpendicularly in front of and perfectly parallel with the camera (a mirror being used the camera is sideways to object, not facing it, as in copying direct).

The easel should be so contrived that it can be raised or lowered and moved right and left, which double motion is managed by having the easel double, the up and down motion being obtained by hanging the back portion like a window sash, the weights being exactly the weight of the whole easel and the pulleys over which the cords go not running too freely.

At the top and bottom of back portions of easel are projecting strips with a rabbet deep enough to allow the front or copying board to slide sideways but not loosely ; this front board should be painted a dead black with white lines in centre from top to bottom and from side to side, these white lines being divided into inches and half inches from the centre so that the drawing may be pinned in the exact centre without trouble.

A convenient size for a copying easel will jbe 5 feet high by 4 feet wide.

In connexion with the camera the only thing left to describe is the focussing cloth which should be quite opaque and of ample size to exclude all extraneous light from behind when focussing.

For focussing the image absolutely sharp a magnifying glass will be required and which may be purchased at any Opticians or Photographic dealers.

Section II. — Wet Collodion Process. The Collodion

Methylated Spirits of Mine (pure) 30 ounces.

Methylated Ether '720 ... ... 40 ounces.

Schering’s Cellodine ... ... 1£ cakes.

Cut the cellodine into thin strips, or, if it be hard, break it up in a clean mortar, and dissolve in the above mixture of Alcohol and Ether, when dissolved that forms the collodion.

The Iodiser is composed of

Bromide of Zinc ... ,, 150 grains.

Iodide of Zinc ... .. ... 350 grains.

Methylated Spirits of Wine ... 10 ounces.

When the salts are dissolved, filter and add to the collodion.

The filtering is best done by placing a pledget of cotton wool in the neck of a glass funnel and passing the iodiser through it and to prevent evaporation, lay a glass plate over the funnel.

The iodiser being added to the collodion shake up thoroughly and allow to stand for a week to settle, then decant into convenient sized bottles for using ; this collodion is ready for use in a week, and will improve with age up to 6 months, after which time it should be mixed with new.

Most photographic manuals say that collodion made with methylated solvents will quickly contaminate the bath and eventually prevent the formation of a properly sensitive film, but that, in my experience, is a total fallacy, and I have used some gallons of collodion of my own make and of commercial, made presumably with absolute solvents ; let the student procure pure sweet-smelling methylated spirits from a respectable chemist and go ahead.

When coating plates with collodion it is not a wise plan to pour the surplus from the plate back into the bottle from which it was poured, but to pour it into another, kept handy for the purpose, the contents of which are, at the end of the day’s work emptied into the stock bottle after such a quantity as is sufficient for next day’s consumption has been decanted into the pourer.

The best bottle from which to pour the collodion upon the plate is the tall capped bottles sold by the dealers as collodion pourers.

The Silver Bath is a most important factor in the production of good negatives and imust be compounded with care and used with skill.

To make it, dissolve 6 ounces of nitrate of silver in 10 ounces of water, then add 10 drops of collodion, and shake up well, then add 70 ounces of water, and let it stand all night; then filter through a pledget of cotton wool packed loosely into the neck of a glass funnel into a clean bottle or jug, such bottle or jug being kept solely for use with the silver bath, as also the glass funnel, then add 1 dram of nitric acid and let it stand all night before trying.

The bath holder may be an upright vessel of the. ordinary pattern, with a dipper with which to lower the plate into the solution, or it may be a flat dish with a cover to keep out light and dust, and using a silver hook to lift the plate from the solution if the former shape be chosen, let the dipper be of glass, porcelain, silver wire, or of wood soaked in melted parafin, but on no account of ebonite as such a dipper will cause spots and derange the bath sooner or later.

If a flat dish be used the best form is that introduced by Mr. H. J. Burton, principal operator of the Autotype Company, which is a wooden dish lined with ashphaltum hanging on a cradle, the lower end being a well to hold the solution, in this form of bath the plate after sensitising is drained thoroughly before taking it out which is a great convenience as not only is silver solution saved but the dark slide will last much longer.

The Bath solution made up as above will be the right strength for work, but as every plate sensitised therein takes away its modicum of silver, after a certain time it must be strengthened as it is essential for the production of good work that the solution be kept at a proper strength. The best way of doing this is to add a dram or two of a saturated solution of nitrate of silver, after each day’s work has been done, and if the solution be worked in a flat bath, it will be as well to pour it into the jug and filter it before using again ; with an upright holder, this filtering will only require to be done about once or twice a week, as any particles of dust, &c., subside and have not the same chance of falling upon the film as in a flat bath, but the addition of the silver solution should be made, and the solution well stirred up with the dipper.

In course of time a silver bath will get contaminated with organic matter from various causes and will also get supersaturated with ether and alcohol and also with Iodo, Bromo, nitrate of zinc, and will either refuse to work or only yield imperfect films and thin images, in which case the best plan will be to take 20 ounces of the solution, dilute it with clean water 60 ounces, filter, and add 6 ounces of nitrate of silver and again filter when a new bath will be the result.

The silver in the rejected portion of the old bath should be precipitated as a chloride by the addition of a solution of common salt, the precipitate dried and sent to the refiner, together with the ashes of the filtering papers, blotting paper used to drain the plates upon, or to wipe the, backs of the plates, after leaving the bath and before putting into dark slide.

The Developing Solution.

First of all purchase 7 lbs. of commercial sulphate of iron (copperas) and put this into a gallon jug and fill up with boiling water (clean) stir up with a clean rod at short intervals for 3 or 4 hours, then allow to stand until the sediment settles and the top portion of solution is clear and bright, then decant as much as possible into a bottle or bottles and label saturated solution of iron, then again fill up the jar with boiling water, stir until as much is dissolved as possible so as to be ready by the time the stock in the bottle is exhausted, repeating the process until all the crystals are dissolved, then wash out the jar, rejecting the residue and begin again.

But bear in mind that unless there are crystals left in the solution after each addition of hot water, it will not be saturated, therefore before taking the solution into use, be sure there are undissolved crystals in the jar.

For use, take of —

Saturated Solution of Iron ... 10 ounces.

Acetic Acid ... ... ... 4 ounces.

Methylated Spirits of Wine — 1 ounce to 5 as required.

In the above solution the alcohol is added to enable the developer to readily assimilate with the sensitive film, and the quantity requisite varies with the age of silver bath, or to be more correct, with the quantity of plates sensitised therein. At first little or no alcohol will be required, but after a number of plates have been sensitised, then the developer refuses to flow evenly and seems as though it wants to run over the edges of the plate, this is a sign that more alcohol is required, and when more has been added the developer will flow evenly as before, but when 80 ounces of developer require over 4 ounces alcohol to make it flow, it is a pretty sure sign that the bath wants re-making.

The developer is applied to the plate after exposure from a straight lipped cup or glass measure which should be kept for the exclusive use of this solution, as the mixture of any of the other solutions with it will at once counteract its working power.

The Fixing or Clearing Solution is made of—

Cyanide of Potassium ... ... 3 ounces.

This solution is highly poisonous both in solution and vapour, so ought to be kept in an upright holder, the plate being lowered into the solution on a dipper, keep the solution well covered up so as to prevent evaporation as much as possible.

After being in use a little time this solution will get weak and should be strengthened by the addition in the evening of a lump or two of Cyanide and then stirred up with the dipper in the morning, the negative must not be left in this solution too long or the density of the film will be impaired, but must be removed and well washed directly all the yellow iodide has been dissolved.

The Intensified No. 1

Chloride of Ammonium ... ... 2 ounces,

dissolve then add —

Bichloride of Mercury ... ... 2 ounces,

dissolve, and filter.

No. 2

Liquor Ammonia '880 ... ... 5 ounces.

Solution No. 1 is best kept in an upright holder, as if kept in a flat dish there is always the danger of cutting the skin with the glass plate and getting the mercurial poison into the system.

No. 2 is kept in a well stoppered bottle and only sufficient for each plate withdrawn when required.

Another method of intensifying for those who object to the use of mercury is to bleach the negative in a solution of —

Ferrid Cyanide of Potassium ) g Red Prussiate of Potash ... )

Nitrate of Lead ... ... ... 4 parts dissolve and filter —

When the plate is bleached wash thoroughly under the tap taking care that the edges and corners of the film are washed as well as the centre, then flood with a sufficient quantity of —

Nitric Acid ... ... ... ... 1 ounce allow this to remain on a few seconds, then wash and flood with sufficient quantity of —

Sulphide of Ammonium ... ... 1 Part which will at once turn the film an intense black, again wash and flood with the Nitric Acid solution and again wash ; then the negative is put away to dry.

This method of intensifying is cheaper than the other and if the washes of acid between and after the other two solutions are carefully done, and the stench of the sulphide not objected to, then there is little or no difference in the results, but if the acid w'ashes are omitted or (and) the sulphide has not been kept corked, and is consequently not fresh, then there is a great danger of a brown stain upon the lines which is more or less fatal to getting a good print on zinc.

The glass used as a support for the collodion film, should be thin flatted crown of the best quality, as the negatives as a rule, are not required again after once the zinc is etched, so that the film is washed off, and the glass used again, which cannot be done so often if the glass is of bad quality, flatness is a sine qua non as it has to be subjected to heavy pressure between a zinc plate, and the front glass of printing frame.

When new the glass merely requires polishing with a clean wash leather kept for this purpose only.

The best way of doing this is to cover a flat board 24 by 18r or thereabouts, with a good American cloth glazed side out, a plate laid upon this will not slip about when being polished.

Both sides and edges of the plate must be well cleaned, as one of the most prolific causes of derangement of the silver bath is from organic matter introduced therein by imperfectly cleaned glass plates.

One side of the plate if gently rubbed with the thumb nail will be found smoother than the other, this being the most suitable side for the support of the collodion film ; this side is polished with the leather until, upon breathing gently upon it, the film of moisture is quite free from marks or streaks, not only in the centre but at the sides and corners.

It is absolutely necessary that the plate be chemically clean all over, else the film of collodion upon drying will split and the negatives be spoilt.

When the plate is clean an edging of india-rubber dissolved in benzole, about an eight of an inch wide, is run all round the edge by means of a small camels hair brush, tied to a stick, the end of stick being level with point of brush, the stick acting as a guard against the brush going too far from the edge.

Glass plates that have been used and not varnished are freed from the films by being immersed in mixture of Hydrochloric or Nitric acid and Water for a few hours, then washed under the tap, and well rubbed with a rag and allowed to dry, when they are polished same as above.

Negatives that have been varnished are cleaned by first immersing in a hot solution of common washing soda until the film comes off, then wash under the tap rubbing well with a rag, then immerse in the acid solution so as to neutralize the alkali ; again washed and dried.

The films that are removed from the glass plates, must not be thrown away, but should be carefully collected, dried and sent to the refiner with the other silver waste, a good plan of saving these films, and at the same time keep the acid and soda solutions clear of them, is to filter each solution occasionally through an old felt hat suspended conveniently over the tanks using one for each of the tanks.

The polishing of the glass plates, must not be done in the dark room, or the crop of comets, spots &c., upon the negatives will be exasperating in the extreme, let this operation be conducted in an extreme corner of the studio, where no other operation will disturb this, and where the fluff from the dusters and leathers will not interfere with any thing else.

Chapter II. Photographic Manipulations

'"PHE chemicals being prepared and in their places in the dark, polish a glass plate, run the edgeing of india-rubber along the sides and allow it to dry, then dust the plate with a flat camel or badger hair brush kept for this purpose only, now attach back to a pneumatic holder and holding the plate face up in a horizontal position, with the left hand, pour upon towards the right hand corner furtherest from the body, a little more collodion than it is judged will be sufficient to cover the plate, let the collodion run to the corner, then incline the slate to the left and the collodion will run into the upper left hand corner, now by inclining towards the body the collodion will flow into the lower left hand corner, and from thence it is guided into the funnel placed in the bottle prepared for its reception ; during the time that this surplus is draining the plate must be gently rocked sideways so that the lines formed by the collodion in draining are merged into each other leaving the him quite homogeneous, as soon as the collodion ceases to drip, release it from the pneumatic holder and touch the lover ridge of collodion and when firm raise the dipper from the bath and place the plate upon the projecting lip collodion film away,, then lower steadily and gently into the solution and when the dipper touches the bottom raise it a quarter of an inch and move the plate gently sideways and up and down (but do not let top. of plate leave the solution) for about 30 seconds so as to prevent streaks in the direction of the dip, in lowering the plate be careful that there is no halt in the operation or else there will be a mark across the film which will spoil it.

The plate will require an immersion of about 3 minutes for proper sensitising and this interval, the Bath being covered up to prevent the access of white light — may be utilized to give the final adjustment to the camera and to see that the drawing or print to be copied is properly in focus.

Use a medium Diaphragm in the lens for focussing and examine the image all over before deciding that it is sharp, focus by preference about half-way between centre of picture and the edges, and when after moving rack to and fro until the proper sharpness is obtained, take out the Diaphragm and substitute the smallest sent out with the lens, or if the picture to be taken be small and from a large original, then the second or third smallest may be used.

Now remove the focussing screen from the Camera (note that the ground round side of glass has been next the lens) and place the cap upon the lens close the door of the dark room, open the dark slide, see that the proper carrier is in it, then raise the plate from the bath slowly and if the film is free from greasy marks the plate is ready, but if the solution does not flow from the plate evenly move up and down, in and out until it does, then release the plate from dipper, and holding it by the fingers of the left hand with a corner resting on edge of bath, lower the dipper back into the solution with the right.

Now with both hands holding the plate in such a manner as to avoid touching the film, allow the solution to drain from the plate as much as possible, then lean the plate against the wall, the lower end resting upon a pad of cleau blotting paper so as to catch any further draining ; now with a pad of blotting paper or papierjoseph wipe the back of plate as dry as possible, which will prevent stains and keep the dark slide from rotting by the action of the silver solution.

The plate being drained, lay a piece of thin filtering paper in each lower corner of carrier so that the plate will rest upon the filtering paper which will catch any further drainings from the film and be a safeguard against stains.

Now lay the plate face down in the carrier of dark slide, close the door and fasten it.

The dark slide is now carried to the Camera and inserted in the grooves previously occupied by the focussing screen, takingnotice that the sliding shutter is next the inside of camera, and.

when pushed quite home cover the back with focussing cloth and pull out the shutter when the plate is ready for the exposure.