BRITISH JOURNAL OF PHOTOGRAPHY. August 15, 1863, p.326
ON THE INTERVENTION OF ART IN THE PRACTICE OF PHOTOGRAPHY.
By M. BLANQUART-EVRARD.
PART II--PRACTICAL MEANS--MANIPULATIONS.
I.--ACTION OF LIGHT.
IF it were possible, we should willingly postpone the publication
in order to make our investigation more complete; but the near
approach of the photographic campaign, and the desire to avoid the
reproach of incompleteness in our directions which might be fairly
brought against us if the results were not obtained which
ought to follow the application of our theory, will not, allow us to
We have said that it was possible to continue out of the camera
the action of light on the image produced, in such a manner as to
increase its intensity.
When it is desired not to light the whole of the negative, those
parts which it is desired to retain in their primitive state must be
protected by screens.
How is this result to be obtained? That is what we now proceed to
show. But it should be at once understood that we do not here
propose to give an artistic lesson. Art is not the result of
chemical reactions or manipulations: it consists in the choice of
effects. We shall show how they are obtained, not where they should
Some parts of a subject have to be sacrificed in order to bring
others out into bolder relief and with greater effect than with an
ordinary method of illumination, as in the magic paintings of
Rembrandt; or ask of Nature a lively and spirited style of
illumination, as in the Spanish school. Photography will be able,
from this time; forth, to produce these two results with the same
Let its observe at first, that there are certain kinds of
negatives which we prefer to others. Thus those of a medium degree
of intensity and full of detail--that is to say, rather weak than
strong--are those with which we are; best satisfied. The following
is the reason:--their deficient intensity causes them to be rejected
in practice, because, in printing, they yield proofs which are too
deep and without brilliancy in the high lights--a condition of
things which is very favourable for our purpose. All those parts
which we desire to keep in relative obscurity are obtained in that
condition by using the negative in its ordinary, condition; that is
to say, that we protect those parts from the action of light while
we expose the others.
Nothing can be more simple; than the means necessary to effect
this object. With a small brush, and some opaque colour well ground
in oil or varnish, we trace out, as correctly as possible, on the
reverse of the cliché--that is to say, on the side not
covered with collodion--the outline of those parts which it is
desired to protect from the action of light; then this being
determined--a matter of great facility by reason of the transparency
of the negative--we cover these parts with a film of opaque
In this state we expose to the sun the painted side of our
The luminous rays pass through those parts not protected by
colour, and it is on these places only that they exercise their
It will be obvious that it is quite possible to arrive at great
perfection in defining the outline of those parts which it is
desired to protect and those which it is desired to expose.
A sufficient amount of sharpness almost is obtained without the
slightest precautions. Further, an amount of sharpness equal to that
produced by an engraver's tool may be obtained if the negative be
exposed on a moveable framework, moving in the meridian, and
according to the elevation of the sun, in order that the rays may
traverse the thickness of the glass in a perpendicular
The mass of high lights being obtained, the working of the
reserves may be proceeded with at pleasure. All those parts of the
negative which are now considered sufficiently exposed must be
covered with colour, in order that those only may now be exposed to
which it is deemed expedient to impart greater depth of colour. It
will be seen that in this way we may, vary, ad infinitum, the
luminous effects, since we. can graduate at discretion the intensity
of the light.
When the desired effect has been obtained, the colour with which
the back of the negative has been covered is removed, and a little
practice will enable the operator soon to appreciate the value of
the lights thus produced.
It is scarcely necessary to mention that if the contemplated
effect has not been fully attained, nothing is more simple than to
re-expose those parts which require to be more deeply printed--an
operation which in some respects resembles that of the engraver, who
continues his labours until. he has obtained what he desires.
II.--OF DE-IODISING. .
The effects due to luminous action being finished, we have at our
disposal two methods-either of which may be adopted, according to
circumstances--for the purpose of de-iodising or fixing.
If the negative under treatment be strongly coloured, and possess
that degree of intensity necessary to give brilliant positive
proofs. it is only necessary to introduce it into a bath of
hyposulphite of soda. The effect of the re-agent may be followed by
the eye. In dissolving the iodide it simultaneously removes the
pearly shade of the collodion film, which then becomes completely
clear and transparent. If, on the contrary, either from insufficient
exposure or want of energy in the light the negative be regarded as
insufficiently intense, it will be necessary to submit it to the
action of chloride of gold according to the very valuable method
suggested by M.. Fizeau for Daguerreotype pictures on silver
Let us recapitulate this method in a few words, to avoid trouble
to those of our reader;, who leave not practised the
Daguerreotype:--The plate, being perfectly levelled on a levelling
stand is flooded with a solution of Sel d'or de Fordos et Gelis
(hyposulphite of soda and gold) as deep as possible. The image thus
covered is uniformly warmed by means of a spirit lamp, under the
orison of which the gold is precipitated and the image is seen to
We propose to replace the Daguerreotype plate by our glass
negative, and let it undergo the same treatment. Whether it has
previously been grey or brown, we shall see it assume a deep black
tint when viewed by transmitted light, and bronze green by reflected
light. The opacity naturally results from the quantity of gold
precipitated; we therefore warm it well in order to have an abundant
precipitate, and we use a very strong solution of gold (containing
one per cent).
This process, as will be seen, constitutes in itself an excellent
method of intensifying; for, far from thickening the high lights and
fogging the shadows--as too often happens when intensifying by means
of a nitrate of silver bath--it gives to the high lights great
solidity without taking away their limpidity, and instead of fogging
the high lights it clears them, so to speak, by beginning the
solution of the iodide of silver in the film.
But for the special case upon which we are now engaged it has an
advantage which does not appertain to any ordinary means of
intensifying, inasmuch as it induces a much more energetic action
upon those parts where the light has twice acted than upon those
parts which have been preserved. Thus, in our own practice, we are
almost tempted to submit all our negatives to the action of sel d'or
After cooling, the excess is collected to serve (after the
addition of see d'or to keep up its strength) again. The negative is
then, treated with hyposulphite of soda to effect the removal of the
iodide: it is then freely washed with water and dried.
We have said that when we had to deal with a weak negative, but
full of detail, as produced by certain reducing agents, especially
sulphate of iron, we could. convert into shaded portions for the
general effect of the picture those portions of the negative which
are exposed to a second action of light. It is possible that by this
simple means we should have shadows enough. When, however, this is
not the case, and it becomes necessary, for effect, to sacrifice
more of certain parts, the following is the method to adopt to
obtain this result:--
Trace upon paper against glass the outline of those parts which
it is desired to put into shadow; cut this out in cardboard or thick
paper, in such a manner that this cardboard being applied to the
proof protects one part, while the other is being exposed.* Prepare then a flat dish, which, being placed
horizontally, should leave some iodine spread over the bottom, over
which the negative, covered by its screen, should be placed. The
vapours of iodine attach themselves to those parts of the image
which remain uncovered, and form with the metal an iodide of silver.
The film is more or less thick, according as the exposure has been
more or less prolonged.
Iodide of silver being soluble in hyposulphite of soda and its
analogues, it is only necessary to pass the negative rapidly through
a solution thereof in order to remove all the iodide formed. By
these means the shadows may be increased to any desired extent,
since it may be carried as far as the complete conversion of all the
metal into iodide.
It is hardly possible to say at what point the iodising should be
stopped, as experience alone can teach this; the operator will,
however, be able to form some judgement from the colour assumed by
It will, of course, be understood that it is always best to keep
within the extreme effect, since one is always free to renew
the operation; as the negative, after iodising, drying, and washing,
tray be submitted to the action of iodine until the image is
Let us conclude by an observation which is not without its
importance. It is, that the operation of iodising is attended with
less danger after the negative has been passed through chloride of
gold, as we showed above. The film of gold which covers the silver
moderates the action. of the iodine, and thus allows it to be
conducted with greater safety to the point where it is desirable it
should be arrested.
* Tracing the outline on glass may be dispensed with if a
positive print be taken, pasted on cardboard, and cut out. In this
manner a more exact outline is obtained than by tracing.