PHOTO-MECHANICAL PROCESSES.
[Sidenote: Photo-mechanical process.]
From our earliest photographic days we always felt that all “ordinary”
printing methods, however good in themselves, would finally have to give
way to photo-mechanical methods, as all processes are called by which the
negative is reproduced. All the photo-mechanical printing processes may be
divided into two great classes:—
[Sidenote: Classification.]
A. Processes in which the aim is to produce diagrams.
B. Processes in which the aim is to produce pictures.
For the first purpose any of the methods are useful: that is, typographic
processes, where the block is set up with the type in the printing-press;
the collotype process, where the prints are subsequently mounted on paper,
or interleaved in a book; and the photo-etching process, where the plates
are introduced between the leaves of a book.
[Sidenote: Diagrammatic plates.]
It is obvious that when the aim is diagrammatic, brilliancy, sharpness,
correct drawing, and the truthful rendering of texture are the requisites,
as in the reproductions of negatives from nature to illustrate scientific
works, books of travel, &c. In such cases these are the main points to be
considered; and when to these considerations is added the question of cost
of production, it is evident nearly all the processes worth mentioning
which are now in existence will serve one or other, or all such purposes.
But when the question comes to be considered from an artistic point of
view, the matter is totally different, for it is a _sine quâ non_ in this
case that all the artistic quality of the original photograph be
preserved. [Sidenote: Art blocks.] Cost must not be considered. From the
art point of view alone, then, we shall briefly discuss these processes.
[Sidenote: Platinotypes.] As we said in a former chapter, of ordinary
printing papers the platinotype is alone worth considering for this
purpose, but for book illustration a serious objection to its use is its
monotony. For, although there are two colours, the charcoal grey and the
sepia, the gamut of colour is very limited; a serious matter this, for our
experience leads us to believe that there is a particular colour and tint
especially suitable to each subject. Another objection to all ordinary
printing papers is the want of relief in the gelatine film of an ordinary
negative, a want which gives a certain flatness in the resulting print,
when compared with a print from a copperplate where the cavi-relievo is
deeper. Relief in the block undoubtedly has a great influence on all
results, and in all the photo-mechanical processes “_depth_” is an
essential, and the best processes are those in which the printing-plates
have the deepest surfaces. Another fact which renders platinotype less
valuable than photogravure is that there is always a certain amount of
“sinking in” of the image, as there is with a painting on canvas; but a
painting can be brought up by varnish, a platinotype cannot.[13]
-----
Footnote 13:
This “sinking-in” is now scarcely appreciable with, the new cold-bath
process.
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Let us, then, examine the various processes, and see which will serve our
purpose.
[Sidenote: Collotypes, Woodbury types, &c. not durable.]
For artistic reasons we are of the opinion that Collotypes, Woodburytypes,
and all such methods, are undesirable; and this we say deliberately, after
long study of the subject, for in supervising and choosing illustrations
for the books which we have illustrated we carefully examined specimens of
nearly all the photo-mechanical processes extant. We say this, although
one writer on the subject of photo-mechanical processes has given out the
opinion that the ideal process is one in which the resulting print should
be a facsimile of a “silver print;” but of course such a remark is
artistically wrong, and is in keeping with the rest of the compilation in
which the statement appears.
[Sidenote: Typographic processes.]
For the benefit of the student, then, we say there are but two processes
to be considered for artistic book illustration—a typographic block to be
printed with the text, and an intaglio copperplate. The typographic block
has the whites lowered like a woodblock; and as it is printed in the
ordinary way, with the type, there is no extra trouble or cost in the
printing. With a copperplate, on the other hand, the plate must be
carefully inked and wiped, and each print separately pulled by hand, the
difference in time taken by this process, and consequently the cost, is
therefore greatly increased.
After a careful examination of all the typographic processes we have no
hesitation in saying that there is _not one_ satisfactory in the market.
When the original picture is not travestied and cheapened by
mechanical-looking crenellations and stipplings, it is marred by obvious
hand-work and by falsity of tonal translation. Any photo-mechanical
process, to be perfect, must, as we have all along maintained, require no
retouching of any kind. All the typographic blocks, too, are too shallow;
hence in the rough working and pressure of the printing-press all tonal
subtleties are lost in smudges, as the block becomes clogged with ink.
Many of these blocks serve remarkably well for rough diagrammatic
purposes, but for artistic purposes there is not one we can recommend when
the object is to reproduce pictures taken from nature. For facsimile work
they serve the purpose. [Sidenote: A great desideratum.] A first-rate
photo-mechanical block to print with the text in the ordinary
printing-press, which is entirely the result of a chemical process, is a
great desideratum, and it is a problem which experimenters in this
direction will do well to study. Not only is it that there is no
typographic block adequate, but in addition, when the present process is
employed for diagrammatic purposes, or to satisfy the pictorial standards
of the untrained in art, they are terribly marred by crude retouchings and
daubings with Chinese white, until such travesties of nature appear that
are only to be equalled by some of the “finishing artists” of the
photographic studio. Yet, bad as these block processes are, they are
infinitely better than the second-rate woodcuts made from photographs. Day
after day, books appear illustrated with woodcuts done from photographs,
in which the woodcutter has effectually ruined all the beauty of the
photograph. If the student, then, should ever be in the position of having
to choose between the facsimile woodcuts of English woodcutters find
photo-mechanical block-work, let him choose the latter as the lesser evil;
it is better than any except the American school of facsimile woodcutters.
And here it may be well to note a dishonest practice which is daily
becoming more common with writers of books of travel who buy photographs
abroad, and unscrupulously have their books illustrated with them. We know
of certain such illustrations which are advertised as being prints from
woodblocks done from _sketches by the author_. Quite recently a book of
travel appeared illustrated with third-rate woodcuts purporting to be done
from sketches by the author, which were really done from photographs
purchased in the shops abroad. We know of one case where this was done in
England, the photographs pirated being English photographs. Should such a
thing ever happen to the student, he must, as a duty to the photographic
world, prosecute without compunction, and exact the utmost penalty of the
law. Such dishonesty is one of the most despicable forms of thieving.
[Sidenote: Photo-etching.]
But to return to our subject. As we have said, we felt from the first that
photo-etching was the ultimate goal to be reached; that was the final end
and method of expression in monochrome photography. We argued the matter
out with many painters, and they agreed with us, as did they agree that
the process of reproduction must be the _result of chemical changes
only_—that no retouching was admissible, or a hybrid would be the result,
and a hybrid is detestable to all artists, although we have recently seen
writers untrained in art matters advocating a photo-etched plate as a
basis for etching or mezzotinting. Having decided, then, on these points,
we determined to try the photo-etching processes of the various firms. On
inquiring from the best English and French firms, we found that but very
few, in most cases no landscapes from nature had been reproduced in this
way, although a few portraits had been done. We carefully examined the
specimens (nearly all specimens of facsimile work) of thirteen different
firms; in fact, all the firms practising photo-etching that we could hear
of. From this examination it was evident that however good many of the
processes were for facsimile work, but few were adaptable to our needs.
Having at last settled on the four apparently most suitable processes, we
began our studies. Negatives were sent to each of these firms, of whom
only one had ever attempted reproducing a landscape direct from a negative
from nature. The proofs came, and were in every case most unsatisfactory;
they had all been barbarously retouched, all the tonality _had been_
falsified, faces against the sky were made lighter than the sky, faces
were roughly outlined with an etching-needle, high lights were scraped
away needlessly, and shadows barbarously deepened with the roulette. Our
battles then began, and we demanded plates free from retouching; the
voluminous correspondence we had on the subject would afford amusement.
Various firms protested—it couldn’t be done; it was absurd; was art the
result of a chemical process? and Heaven knows what! However, we persisted
with inflexibility, and though we had to accept in some cases the least
visibly retouched plates, we finally gained the day all round, in so far
that all the firms supplied us with plates with no visible retouching.
Thus was instituted a new departure, negatives from nature were
reproduced, through our battlings, with no visible retouching; and
although a few diagrammatic negatives had been reproduced here and there
before us, we were the first to start the serious reproduction of
negatives from landscapes and figure subjects which could be regarded as
pictures _per se_, and not merely as topographical views.
[Sidenote: Typographic Etching Company’s process.]
But now the coast is clear, and the student can get his negatives done
without visible retouching by asking for it. From an examination of these
results it was soon evident that one firm, the Typographic Etching
Company, produced plates immeasurably superior to those of any other firm,
and in addition, they would guarantee their production _without
retouching_.
For reproducing negatives taken from nature, then, this process is
_perfect_, and we cannot see how any photo-engraving process will ever
surpass it. [Sidenote: Messrs. Dawson and Colls.] Mr. Dawson and Mr. Colls
are trained artists, and perhaps therein lies the secret of their success.
It is perhaps invidious to select one firm for special mention, but as the
results of Mr. Colls and the Typographic Etching Company are in every way
so superior when artistically considered, we feel it our duty to record
the fact here for the benefit of the student. Quite recently there has
been much discussion on the vital question of “Photogravures _v._
Engravings,” and some of the English firms have publicly announced that it
is necessary to finish their work by hand, while others privately
maintained the same fact. Mr. Colls, late of the Typographic Etching
Company, on the other hand, maintains that a plate, perfect in quality,
can be produced without the aid of a touch by hand. Further on will be
found a communication on the process by the etcher, Mr. Colls, who therein
states that he can and does produce his work without any retouching.
The Dawson process renders the light in the shadows better than any of the
other processes, this being effected by the method of working, and, as a
whole, the “quality” of the work is unapproachable, it beats mezzotint out
of the field in its subtlety and delicacy.
[Sidenote: English _v._ French photogravure.]
And here we would caution the gentlemen of the press who have lately
written so freely and so mistakenly on the subject of photogravure, that
the best photogravures are _not_ produced in France, but in England.
Englishmen do not seem to know when they possess a “good thing.”
We venture to say, without any diffidence, that for the reproduction of
negatives from nature, Dawson’s process is _facile princeps_, and to
assert that for the reproduction of pictures, some of the English
processes are equal to, if not superior to, the continental processes.
This is also the opinion of several artists who have seen specimens of the
work done in both countries. The process, as worked in America, does not
give results equal to those obtained in England. For diagrammatic
purposes, we consider nearly all of the English processes possess
qualities of equal value.
Another new departure for which we had some battling was a _minor_ point,
but an _important_ one. It was on the question of lettering. It had been
the practice of many of the firms to engrave in plain lettering beneath
the picture, the name of the firm, and the words “negative by ——,” and
often in addition the word “copyright.” This engraving, as it was usually
done, gave a “cheap” look to the picture. We felt that the picture was
injured by this procedure, so we insisted that our name should be cut in
the picture, in a quiet manner, as an etcher would sign his name, and that
no ordinary engraving should appear on the plate. In case, then, our
student should at any time have any of his works reproduced, we will give
him a few hints, for though the publisher does the business part, the
artist always has the passing of the plates.
[Sidenote: Hints for those having plates reproduced by photo-etching.]
When sending his plates, then, to be bitten, he should send a well-printed
platinotype print with them, a print having just the effect he wishes for
in the copper-plate. If clouds are to be introduced, the cloud negative
should be sent as well. He will in due time receive a proof, which he must
go carefully over, making any notes on the margin as to re-biting, &c. If
it be retouched or utterly bad, it must be rejected. Of course, it is here
evident that his art knowledge will come in, for if ignorant of art, how
can he make remarks to the “biters” who are often artists? He must
continue asking for proofs until he receives a satisfactory one, for no
plate can be forced upon him if he can prove it to be wrong. If he have
real grounds for objection, he will find the English firms most generous,
for they take a pride in their work. They have, in some cases, made as
many as three plates from a subject for us, with no extra charge, and this
we could never get a French firm to do. When he approves of the plate, he
signs the proof to that effect. Then comes the great question of “colour,”
that is the coloured ink to be used; for one of the great advantages in
photo-etching lies in the number of colours and shades of colours which
can be used. Here, again, his artistic knowledge comes in, and he will
find the effects produced by different colours are marvellous. Having,
then, suggested his colour and tint, he will receive proofs printed in
them, and he finally decides upon the tint suitable for each plate, and
these are kept as standards on a file. The matter of printing papers, too,
offers great variety and scope for artistic selection; but here the
student will find he has not a free hand, the publisher often limiting his
choice in that on financial grounds. The student must see, however, that
if India paper be used, an unsuitable tint be not selected. For example,
India paper may be yellow or white, obviously then, if the plate is to be
printed in bartolozzi red, white India must be used, and not the ordinary
yellow-tinted India. The student must be careful when sending his
platinotype print, to cut it exactly to the limits he wants the picture on
copper. Copper-plates can be produced in this way from prints in cases
where the negative has been broken. If the sky is not an important part of
the picture, it is better to have it a flat grey tint, or delicately
gradated. The student, of course, remembering certain physical truths, as,
for example, that still water is, as a rule, lower in tone than the sky
which it reflects, &c. The best test of relative value of sky and water is
to turn the _picture upside down_. All these subtleties must be carefully
considered, for a sky lower in tone than the still water reflecting it,
would, with rare exceptions, be a fatal artistic error, and enough to
condemn the plate. The details which thus go to make or mar a picture are
countless.
[Sidenote: W. L. Colls on photo-etching.]
This, then, is our experience of the photo-mechanical processes, and, as
we make it a rule never to write on anything we have not full _practical_
knowledge of, we have asked our friend, Mr. Colls, to write us some
particulars of these processes. We have done this because there are
certain misleading books in the market on the subject, written by men
without such special knowledge as can only be obtained by a man who has
worked at the process for years and at nothing else, and who is, in
addition, an artist. Mr. Colls is both a specialist and an artist in this
work. In our opinion the future artists who practise photography will also
photo-etch their own plates, which is greatly to be desired, but since
these processes are at present kept very secret, this knowledge cannot now
be acquired. Nevertheless, we feel that the day is not far distant when
every artist who expresses himself by photography will also bite his own
plates and make his own blocks, and the prints will be published by
print-dealers as etchings are now. This, in our opinion, is the only
method which can give full artistic satisfaction. A final important
consideration is the number of good prints which can be pulled from each
plate. Dawson’s plates, being bitten deeper, will obviously stand more
wear and tear than the others, and will produce a greater number of good
impressions. Mr. Colls thinks that at least 3000 good impressions can be
pulled from each plate, if the steel-facing will last. We append Mr.
Colls' remarks:—
METHODS OF REPRODUCING NEGATIVES FROM NATURE FOR
THE COPPER-PLATE PRESS.
[Sidenote: Preamble.]
“In giving a description of the various methods that are employed for
reproducing photographs from nature for the copper-plate press, it is
obvious that only those which are purely ‘automatic’ need be mentioned, as
it is impossible to give a true rendering of those beautiful forms and
delicate gradations of tone, which we see in nature, by any but automatic
means. For so ever-varying and sudden are her changes, that it is by
photography alone we are able to secure these effects, and having obtained
them, we require a process which will give us _our_ impressions, and one
which will harmonize with printed matter when required for book
illustration.
“This we have in the Intaglio plate, which gives the most perfect
tonality, and possesses all the richness and quality of a mezzotint plate,
with the same degree of permanency.
[Sidenote: Grown and bitten plates.]
“For convenience of description the different methods of producing
Intaglio plates may be classed under two heads—‘Grown’ and ‘Bitten.’ I
will first mention the ‘grown,’ and will endeavour to point out the
characteristics of the different processes, so that a comparison may be
made between them, with the object of determining the one best suited for
the purpose. In all the growing methods the basis of the process consists
in obtaining a gelatinous mould of the subject; the most usual and simple
way being to develop a carbon print from a reversed negative on a polished
copper-plate which has been previously silvered, to prevent the copper
which is afterwards deposited upon it adhering; and to produce the grain
which is necessary to hold the printing ink. The mould when wet is dusted
over with powdered glass, sand, or the like, previously treated with wax
or stearine, to assist its removal.
“When the mould is quite dry the gritty particles are removed by gentle
rubbing, leaving the gelatine in a grained state. Plumbago is then rubbed
well over the picture to render the mould conductive, and it is placed in
the electrotyping battery and a stout cast taken. There is some little
uncertainty attending the entire removal of the gritty particles, and
great danger that in making the mould sufficiently conductive in the heavy
portions, the fine work is destroyed by getting blocked with the plumbago.
The former objection has been overcome by substituting powdered resins,
which can be readily dissolved away without injury to the mould, and the
latter by the introduction of a tissue containing granular plumbago, which
while producing the necessary grain for holding ink, is one of the best
conductors of electricity, so that no after-treatment is required.
“Similar to this is a process by which the grain is obtained by the action
of light on a chemical substance, which crystallizes under the action of
light, the crystals becoming larger the longer they are acted on by it. A
deposit of copper is then made on the crystalline surface and a plate
obtained.
“By these methods very satisfactory results may be obtained for certain
classes of work where the range of tone is not great, they are more
particularly suited for reproducing the works of early engravers, old
cuts, etchings, pencil and crayon drawings, and similar work upon rough or
grained surfaces. In fact, when printed upon old paper, as is sometimes
done in particular cases, so closely do they resemble the originals, that
the most expert judge would have great difficulty in detecting the
reproduction from the original; but for reproducing nature work, where the
scale ranges from the highest lights to the deepest shadows, these methods
are not suitable without much hand-work, which is ruinous to the faithful
rendering of the subject, and the introduction of the roulette which is
used to give the necessary depth does not improve the appearance, as the
depth obtained by it is heavy, and lacking that transparency which is so
desirable in all classes of work from nature. The great drawback to these
methods is that the grain produced is upon the surface of the plate,
standing up in innumerable little prickles, and the only way of working up
a plate is with the roulette and scraper (the nature of the grain being
unsuited for re-biting). These, added to the soft nature of grown copper,
as compared to rolled or hammered copper, which is used in the biting
methods, necessitates the greatest care in printing, and usually require
very strong and sometimes forcing inks to give the necessary strength, and
although a plate be steel-faced it will not hold out for a large number of
impressions.
“There are other ways of producing a grain upon a gelatinous mould by
re-sensitizing and, when dry, dusting over the picture brocade powder,
either coarse or fine, as the subject may require; the mould being
previously treated with vaseline, or a similar substance, to allow of the
powder adhering, and exposing to daylight for a short time. The powder is
then removed, and it is ready for the battery, after being blackleaded. As
all the growing methods resemble each other so closely, I will not mention
any others, but will proceed with a short description of the biting
processes.
[Sidenote: Biting process.]
“A polished copper-plate, preferably a hammered one, is thoroughly
cleaned, to remove all traces of grease, and is dusted over with powdered
asphalt or resin, and the plate heated until the powder becomes partially
melted. A carbon print from a reversed transparency is next developed upon
the grained plate and allowed to dry. The unprotected margin is then
painted round with asphalt, or other resist-varnish, and a wall of
bordering wax placed round the work. It is then ready for biting, which is
done with perchloride of iron, the bare portions being first attacked;
water is then added, and the biting proceeds to the next tone, and so on,
adding water when required, until the solution has penetrated the thickest
portions of the film. The greatest care must be exercised during this
operation, and a careful watch kept lest the action remain too long on any
part. The biting should proceed in a gradual manner, so that the values
are not exaggerated. The plate is then rinsed in water, the bordering wax
removed, and the pigment cleaned off with a little potash ley.
“The biting of a plate resembles very closely the development of a
dry-plate positive, as the action may be seen throughout the operation as
each successive tone is reached. There are many variations to the above
method, and each worker has his particular way of producing the grain,
making the mould, biting, &c., but they are all based on the one just
described. As the introduction of the biting methods as commercially
worked is of more recent date than the grown, less is known of it, and
those who work it most successfully keep it secret, and were it known
there is little likelihood of its being satisfactorily worked by any but
those experienced in copper-plate work, as long and careful study is
necessary to master those minute details which are so important to ensure
good results. For so delicate are the operations, that the changes of
weather, temperature, &c., play an important part, and must be attended
to.
“One of the great advantages a bitten plate has over a grown is that the
scale is greater than by any other method, and the nature of the grain
admirably lends itself to re-biting should any parts require deepening.
That is, re-entering the original work by covering the grained surface
with a protective coating, which resists the action of the acid
etching-fluid, and deepening those parts that may require it, stopping out
with resist-varnish any portion where deepening is not wanted. This at
once does away with the roulette, and the plate still maintains its
original character. Re-biting is seldom required on a plate from nature,
_for with care a plate can be made which needs no after-work whatever, and
when bevelled and steel-faced is ready for the press, notwithstanding the
assertion that has been made to the contrary, which recognizes the process
only as a basis for skilled after-work_. It is needless to say that in all
mechanical processes the very best negative is required to work from, for
although a great deal may be done in the biting to counteract any defects
in the negative, yet, if the negative is wanting in any particular, the
after-result is sure to suffer. And here I wish to say that by the ‘very
best negative’ I do not mean the ordinary photographer’s beau-ideal, but a
negative which gives a true impression of the object photographed, and is
full of the ‘quality’ and subtlety of nature.
“The grain obtained on a plate which is bitten, differs materially from
one that is grown, inasmuch as in the former it is below the surface, and
in the latter upon it, as previously described; consequently its wearing
capabilities are far greater.
[Sidenote: Another biting method.]
“Another biting method which possesses the merit of ingenuity rather than
utility, is of converting an ordinary bromide of silver positive into
chloride of silver, by the action of perchloride of iron and chromic acid.
The film when damp is brought into close contact with the face of a
polished copper-plate. Chloride of silver now rests upon the copper-plate,
more of it in the vigorous or dark portions, and less of it in the
lighter, and by a galvano-chemical process the chloride of silver
decomposes, forming metallic silver and soluble chloride of copper, and
producing depths corresponding to the amount of chloride of silver
present. The energy of the action may be increased by moistening the film
with a weak solution of chloride of zinc, and a battery current seems
necessary to produce good results. As can be seen, the process is a very
delicate one, admitting of little if any latitude in working, and, unlike
the first-mentioned biting process, will not permit of any work being put
on the positive as is usually done in the first method for certain work
where the darks are very hard and pronounced, and a great saving of
after-labour avoided.
“It is advisable to say that the work done on the positive and plate to
which I refer is done in connection with facsimile work, and not with
‘nature work,’ for in the reproduction of engravings the deep blacks of
the engravings have to be reproduced, and since in nature there is no
black of this kind we do not have to accentuate parts of the plates to
produce it.”