OIL _vs._ BROMOIL
OIL PRINTING AND BROMOIL PRINTING.—Oil printing and bromoil printing
are frequently considered as two different photographic processes. From
this premise different conclusions have been drawn, thus for instance,
that oil printing is more suitable for certain subjects and that bromoil
printing is to be preferred for other purposes. There has also been
discussion as to which of the two processes deserves the preference,
which produces the finer artistic effects, and so on.
All these discussions are, however, superfluous, for the assumptions on
which they are based are erroneous. Oil printing and bromoil printing are
actually not two essentially different techniques. In both cases there
is one and the same process; _oil and bromoil printing are basically
identical_. This can be proved both theoretically and practically.
_The theoretical considerations_ are as follows: in most photographic
processes the chemical property of certain substances of being changed
by action of light is used for the production of the final image.
Such photochemical processes only play a preparatory rôle in oil and
bromoil printing. The production of the final image is here based on
a physical property of the gelatine, namely on its innate possibility
of being tanned or hardened. In oil and bromoil printing an image is
first formed in the gelatine photochemically. This image is, however,
not the final one; it is merely a means to an end. Its actual
purpose is the attainment of a suitable tanning of the gelatine. The
photochemically produced image is therefore removed, but in such a way
that simultaneously with the elimination of the image, the gelatine
which carried it is proportionately tanned in the lights and shadows of
the picture. Only by this tanning is the gelatine made ready for the
production of the final picture. The purpose of these preliminary steps
is the production of the tanned image in the gelatine, which by itself
is invisible or scarcely visible. After carrying out the preliminary
processes the result is a pure gelatine film, which shows places of
greater and lesser tanning corresponding to the photochemical image which
has disappeared and which, therefore, has greater or lesser capacity for
swelling in these places. If at this stage there are still chemicals in
the film they are of no value for the further processes.
If a gelatine film thus prepared is swollen in water, the untanned places
suck up water, while the tanned parts do not take it up. Fatty inks,
applied with suitable brushes, are then repelled by those parts of the
gelatine which hold the water, while the tanned parts of the film freely
take the greasy ink. The final image, therefore, is not formed until the
inking-up of the film with greasy inks.
_This technique may, therefore, be most suitably characterized by
the name “inking-up process.” The usual names oil print and bromoil
print merely designate, although in terms which are terminologically
unsatisfactory, two methods of preparing the base for the inking-up
process._
Oil and bromoil printing are, therefore, nothing more than the two
methods which have hitherto been at our disposal for the production of a
tanned image in gelatine.
Both methods lead to the same result; only the bromoil method is by far
the more complete technically, as is shown in the following discussion.
In oil printing, printing is effected direct on a bichromated gelatine
film. The chromate image is only faintly visible and is not easy to
judge. From its nature it has a very short scale of tones and, therefore,
only gives satisfactory prints from soft harmonious negatives, while
with more contrasty negatives it must inevitably fail; if with such
negatives the high lights are correctly printed, the shadows have long
lost all details; if the shadows are correctly exposed, the high lights
are wanting in detail. Control of the chromate image is only possible
to a very moderate extent. This chromate image is washed out and leaves
behind as a result the tanned image in the gelatine, in which all the
disadvantages of the short scale of tones are inherent, and which besides
this can be far less easily inked-up than a tanned image prepared by the
bromoil method.
The process of bromoil printing has been fully explained in this book;
a direct comparison of the two processes will be made very briefly. A
correct print is prepared on a suitable bromide paper, either by contact
or enlargement. Through the possibility of using direct enlargement, the
enlarged negative, necessary in oil printing, is done away with. The
bromoil image, in contradistinction to the chromate image is visible, and
can be controlled in the most varied ways to attain the desired artistic
effect. It has a much greater scale of tones than the chromate image; and
this can in addition be increased in the subsequent processes far beyond
the possible gradation of the bromide print. The resulting bromide image
is then removed by a bleaching solution containing bichromate, and in
this way the tanned image is formed in the gelatine.
_Oil printing and bromoil printing, therefore, lead to the same
result; but the tanned image, obtained by way of the bromoil print, is
qualitatively of much greater value, for it has a much better gradation._
The opinion is frequently expressed that it is a specific property of the
oil print to give pictures of a peculiarly artistic character.
It is, however, absolutely erroneous to assume that the same effect
cannot be obtained in a bromoil print. As already mentioned, the tanned
images produced in the two methods are alike, but the bromoil print may
have a far longer scale of tones.
The rich gradation of the bromoil print is however not present from the
beginning, but is only produced by allowing it to swell in water of
suitable temperature. The warmer the water used, the longer is the scale
of tones, naturally within definite limits.
_In bromoil printing it is therefore entirely at the choice of the
operator whether he will or will not make use of the long scale of tones
which the process can give._
If cold water is used for the soaking, the gradation of the tanned image
is much less than that of the oil print or the bromide image. _By the
choice of a suitable temperature of the water, the short gradation of
the oil print with all its peculiarities can be exactly obtained._ With
higher temperatures the gradation may be finally increased far beyond
that of the original bromide image.
If one knows and has mastered the properties of the tanned image produced
by the bromoil print, one may easily obtain the same effects as with oil
printing; one can, on the other hand, obtain incomparably more than with
the latter. No limitation is imposed on artistic aims by the imperfection
of the tanned image.
The following shows the _practical comparison_ of the two methods:
if we have before us prints with gelatine films which contain tanned
images, of which one has been produced by the oil process, the other by
bromoil, they behave absolutely alike in the inking-up, for the bromoil
print receives, by soaking in cold water, a gradation which is just as
short as that of the oil print. _The two prints absolutely cannot be
differentiated in practice_, and are indistinguishable, if the paper, on
which the gelatine film is supported, or the structure of the gelatine,
does not give one a hint.
_In such cases it is impossible to determine from the finished print
whether the picture was made by oil or bromoil printing._ The portfolios
of some of my friends furnish striking proof of this; the authors
themselves can no longer recall by which of the two processes some of
their earlier pictures were made.
Nevertheless the opinion is often held that one can obtain pictures
of much finer artistic quality by means of oil printing, because the
prints thus made have a characteristic tonality and better treatment of
masses. This opinion may be explained by the fact that oil printing has
been used longer and is better known than bromoil, and that first class
bromoil prints have not often been exhibited in public until recently.
Especially, it has not been widely known how manifold are the effects
that can be produced by the different methods of working described in
this book.
There is also another explanation. Whoever has completely mastered any
process and has kept in view a definite artistic purpose, will as a
rule find that the process will give him the results which he desires.
It is now an indisputable fact that even such an imperfect process as
oil printing has many times, because of this very imperfection, led to
results which have been proclaimed as artistic. If for instance, an oil
print is made from a contrasty negative, the process cannot correctly
reproduce the tone values of the negative. The short gradation sets a
limit to the inking-up, before the tone values of the negative are fully
developed. The result is then certain to be a gloomy print with heavy
masses. Technically, however, this means nothing more than that the
high lights are not clean and the shadows lack detail. This does not
imply that the resultant picture may not have an artistic effect. _The
question is only whether this effect was actually tried for_ or whether
necessity was not made a virtue and the imperfections of the process
called an advantage. _Without question, the worker who intentionally
strives for a given artistic effect can attain this easily and certainly
by means of bromoil._ If, however, he has no definite aim, but allows
himself to be blindly driven on, as it were, by the idiosyncrasies of
the process, it may happen that he will obtain quite another result.
The greater gradation of the bromide print may induce him to keep on
working on the picture until he finally obtains a print, which exactly
corresponds in tone values with the gradation of his contrasty negative,
which could not happen with the oil print. In such cases one often hears
the opinion expressed that the special quality of the oil print cannot
be attained in bromoil, and that a similar result could be obtained by
any process, even printing-out paper. But the fault does not lie in
the bromoil process, but in the fact that the worker has not mastered
it, and has been carried beyond his aim by its greater possibilities.
_Oil printing is satisfactory when one desires a shorter gradation than
is present in the negative; beyond this, however, it fails. Bromoil
printing, on the contrary, permits on the one hand the shortening of the
tone gradations of the negative to any desired extent, on the other hand,
however, the extension of the gradation beyond that of the negative._ It
offers, therefore, to the artistic aspirant a far greater liberty and in
every respect a technically more perfect and therefore more effective
instrument. By bromoil printing, therefore, one can prepare at will from
a given negative, either a low-toned picture without detail, or one
richly modeled and full of detail and vigor. _Oil printing does not offer
this alternative._
If, in spite of all this, erroneous ideas as to assumed fundamental
differences between oil and bromoil printing, and particularly as the
special suitability of oil printing for certain effects are still
disseminated, the reason usually lies in the fact that many who have
previously worked in oil have drawn erroneous general conclusions from
their first and naturally imperfect results in bromoil printing. They
overlook the fact that even the worker experienced in oil printing must
first learn bromoil printing and then practice it thoroughly in order
to master it. The oil printer does not bring to it anything beyond
a brush technique, which is not sufficient for every bromoil print.
Everything else must be newly acquired; especially an actual mastery
of the technique of bromide printing, which many lack, though they
believe they possess it. Conservative thought easily overvalues its
own possessions and is likely to show itself somewhat antagonistic to
new accomplishments which cost new efforts. The worker who spares no
trouble to make himself a thorough master of bromoil printing will be in
possession of a technique which renders feasible, by its extraordinary
many-sidedness and capacity of expression, the solution of the most
difficult problems of artistic photography.