We shall now proceed to describe the various processes for Photogenic
drawing on paper; first, however, impressing on the mind of the
experimenter, the necessity which exists for extreme care in every
stage of the manipulation. In this portion of my work I am entirely
indebted to the works of Professors Hunt, Fisher and others.
I. APPARATUS AND MATERIALS.--Paper.--The principal difficulty to be
contended with in using paper, is the different power of imbibition
which we often find possessed in the same sheet, owing to trifling
inequalities in its texture. This is, to a certain extent, to be
overcome by a careful examination of each sheet, by the light of a
candle or lamp at night, or in the dark. By extending each sheet
between the light and the eye, and slowly moving it up and down, and
from left to right, the variations in its texture will be seen by the
different quantities of light which pass through it in different parts;
and it is always the safest course to reject every sheet in which
inequalities exist. Paper sometimes contains minute portions of
thread, black or brown specks, and other imperfections, all of which
materially interfere with the process. Some paper has an artificial
substance given to it by sulphate of lime (Plaster of Paris); this
defect only exists, however, in the cheaper sorts of demy, and
therefore can be easily avoided. In all cases such paper should be
rejected, as no really sensitive material can be obtained with it.
Paper-makers, as is well known, often affix their name to one half the
sheet; this moiety should also be placed aside, as the letters must
frequently come out with annoying distinctness. Well sized paper is by
no means objectionable, indeed, is rather to be preferred, since the
size tends to exalt the sensitive powers of the silver. The principal
thing to be avoided, is the absorption of the sensitive solution into
the pores; and it must be evident that this desideratum cannot be
obtained by unsized paper. Taking all things into consideration, the
paper known as satin post would appear to be preferable, although the
precautions already recommended should be taken in its selection.
Brushes.--The necessary solutions are to be laid upon the paper by
brushes. Some persons pass the paper over the surface of the
solutions, thus licking up, as it were, a portion of the fluid; but
this method is apt to give an uneven surface; it also rapidly spoils
the solutions. At all events, the brush is the most ready and the most
effectual means.
Distilled Water.--All the water used, both for mixing the solutions,
washing the paper, or cleaning the brushes, must be distilled, to
obtain good results, for reasons before specified.
Blotting Paper.--In many instances, the prepared paper requires to be
lightly dried with bibulous paper. The best description is the white
sort. In each stage of the preparation distinct portions of bibulous
paper must be used. If these be kept seperate and marked, they can be
again employed for the same stage; but it would not do, for example, to
dry the finished picture in the same folds in which the sensitive paper
had been pressed. A very convenient method is to have two or three
quarto size books of bibulous paper, one for each seperate process.
Nitrate of Silver.--In the practice of the photographic art, much
depends on the nitrate of silver. Care should be taken to procure the
best; the crystalized salt is most suitable for the purpose. While in
the form of crystal it is not injured by exposure to light, but the
bottles containing the solutions of this salt should at all times be
kept wrapped in dark paper, and excluded from daylight.
II. DIFFERENT METHODS OF PREPARING THE PAPER.--Preparation of the
Paper.--Dip the paper to be prepared into a weak solution of common
salt. The solution should not be saturated, but six or eight times
diluted with water. When perfectly moistened, wipe it dry with a
towel, or press it between bibulous paper, by which operation the salt
is uniformly dispersed through its substance. Then brush over it, on
one side only, a solution of nitrate of silver. The strength of this
solution must vary according to the color and sensitiveness required.
Mr. Talbot recommends about fifty grains of the salt to an ounce of
distilled water. Some advise twenty grains only, while others say
eighty grains to the ounce. When dried in a dark room, the paper is
fit for use. To render this paper still more sensitive, it must again
be washed with salt and water, and afterwards with the same solution of
nitrate of silver, drying it between times. This paper, if carefully
made, is very useful for all ordinary photographic purposes. For
example, nothing can be more perfect than the images it gives of leaves
and flowers, especially with a summer's sun; the light, passing through
the leaves, delineates every ramification of their fibres. In
conducting this operation, however, it will be found that the results
are sometimes more and sometimes less satisfactory, in consequence of
small and accidental variations in the proportions employed. It
happens sometimes that the chloride of silver formed on the surface of
the paper is disposed to blacken of itself, without any exposure to
light. This shows that the attempt to give it sensibility has been
carried too far. The object is, to approach as nearly to this
condition as possible without reaching it; so that the preparation may
be in a state ready to yield to the slightest extraneous force, such as
the feeblest effect of light.
Cooper's Method.--Soak the paper in a boiling hot solution of chlorate
of potash (the strength matters not) for a few minutes; then take it
out, dry it, and wet it with a brush, on one side only, dipped in a
solution of nitrate of silver, sixty grains to an ounce of distilled
water, or, if not required to be so sensitive, thirty grains to the
ounce will do. This paper possesses a great advantage over any other,
for the image can be fixed by mere washing. It is, however, very apt
to become discolored even in the washing, or shortly afterwards, and
is, besides, not so sensitive, nor does it become so dark as that made
according to Mr. Talbot's method.
Daguerre's Method.--Immerse the paper in hydrochloric (or as it is more
commonly called, muriatic) ether, which has been kept sufficiently long
to become acid; the paper is then carefully and completely dried, as
this is essential to its proper preparation. It is then dipped into a
solution of nitrate of silver, and dried without artificial heat in a
room from which every ray of light is carefully excluded. By this
process it acquires a very remarkable facility in being blackened on a
very slight exposure to light, even when the latter is by no means
intense. The paper, however, rapidly loses its extreme sensitiveness
to light, and finally becomes no more impressionable by the solar beams
than common nitrate paper.
Bromide Paper.--Of all common photographic paper, the best, because the
least troublesome in making, and the most satisfactory in result, is
that which is termed bromine paper, and which is thus
prepared:--Dissolve one hundred grains of bromide of potassium in one
ounce of distilled water, and soak the paper in this solution. Take
off the superfluous moisture, by means of your bibulous paper, and when
nearly dry, brush it over on one side only, with a solution of one
hundred grains of nitrate of silver to an ounce of distilled water.
The paper should then be dried in a dark room, and, if required to be
very sensitive, should a second time be brushed over with the nitrate
of silver solution.
In preparing the papers mentioned above, there are two circumstances
which require particular attention. In the first place, it is
necessary to mark the paper on the side spread with the solutions of
nitrate of silver, near one of the extreme corners. This answers two
purposes: in the first place it serves to inform the experimentalist
of the sensitive surface; and secondly, it will be a guide as to which
portion of the papers has been handled during the application of the
solution, as the impress of the fingers will probably come out upon the
photograph. The second caution is, that the application of the
sensitive solution (nitrate of silver,) and the subsequent drying of
the paper, must be always conducted in a perfectly dark room, the light
of a candle alone being used.
[Illustration: Fig. 29 (hipho_29.gif)]
III. PHOTOGENIC PROCESS ON PAPER.--Method.--The simplest mode is to
procure a flat board and a square of glass, larger in size than the
object intended to be copied. On the board place the photographic
paper with the prepared side upwards, and upon it the object to be
copied; over both lay the glass and secure them so that they are in
close connection by means of binding screws or clamps, similar to g. g.
fig. 29. Should the object to be copied be of unequal thickness, such
as a leaf, grass, &c., it will be necessary to place on the board,
first, a soft cushion, which may be made of a piece of fine flannel and
cotton wool. By this means the object is brought into closer contact
with the paper, which is of great consequence, and adds materially to
the clearness of the copy. The paper is now exposed to diffused
daylight, or, still better, to the direct rays of the sun, when that
part of the paper not covered by the object will become tinged with a
violet color, and if the paper be well prepared, it will in a short
time pass to a deep brown or bronze color. It must then be removed, as
no advantage will be obtained by keeping it longer exposed; on the
contrary, the delicate parts yet uncolored will become in some degree
affected. The photogenic paper will now show a more or less white and
distinct representation of the object. The apparatus figured at 29
consists of a wooden frame similar to a picture frame; a piece of plate
glass is fixed in front; and it is provided with a sliding cover of
wood, c., which is removed when the paper is ready to be exposed to the
action of the light. The back, d., which is furnished with a cushion,
as just described, is made to remove for the purpose of introducing the
object to be copied, and upon it the prepared paper; the back is then
replaced, and, by aid of the cross piece and screw, e., the whole is
brought into close contact with the glass.
The objects best delineated on these photographic papers, are lace,
feathers, dried plants, particularly the ferns, sea-weeds and the light
grasses, impressions of copper plate and wood engravings, particularly
if they have considerable contrast of light and shade--(these should be
placed with the face downwards, having been previously prepared as
hereafter directed)--paintings on glass, etchings, &c.
To fix the Drawings.--Mr. Talbot recommends that the drawings should be
dipped in salt and water, and in many instances this method will
succeed, but at times it is equally unsuccessful. Iodide of potassium,
or, as it is frequently called, hydriodate of potash, dissolved in
water, and very much diluted, (twenty-five grains to one ounce of
water,) is a more useful preparation to wash the drawings with; it must
be used very weak or it will not dissolve the unchanged muriate only,
as is intended but the black oxide also, and the drawing be thereby
spoiled.
But the most certain material to be used is the hyposulphite of soda.
One ounce of this salt should be dissolved in about a pint of distilled
water. Having previously washed the drawing in a little lukewarm
water, which of itself removes a large portion of the muriate of silver
which is to be got rid of, it should be dipped once or twice in the
hyposulphite solution. By this operation the muriate which lies upon
the lighter parts will become so altered in its nature as to be
unchanged by light, while the rest remains dark as before.
It will be evident from the nature of the process, that the lights and
shadows of an object are reversed. That which is originally opaque
will intercept the light, and consequently those parts of the
photogenic paper will be least influenced by light, while any part of
the object which is transparent, by admitting the light through it,
will suffer the effect to be greater or less in exact proportion to its
degree of transparency. The object wholly intercepting the light will
show a white impression; in selecting, for example, a butterfly for an
object, the insect, being more or less transparent, leaves a
proportionate gradation of light and shade, the most opaque parts
showing the whitest. It may be said, therefore, that this is not
natural, and in order to obtain a true picture--or, as it is termed, a
positive picture--we must place our first acquired photograph upon a
second piece of photogenic paper. Before we do this, however, we must
render our photograph transparent, otherwise the opacity of the paper
will mar our efforts.
To accomplish this object, the back of the paper containing the
negative, or first acquired photograph, should be covered with white or
virgin wax. This may be done by scraping the wax upon the paper, and
then, after placing it between two other pieces of paper, passing a
heated iron over it. The picture, being thus rendered transparent,
should now be applied to a second piece of photogenic paper, and
exposed, in the manner before directed, either to diffused day-light or
to the direct rays of the sun. The light will now penetrate the white
parts, and the second photograph be the reverse of the first, or a true
picture of the original.
Instead of wax, boiled linseed oil--it must be the best and most
transparent kind--may be used. The back of the negative photograph
should be smeared with the oil, and then placed between sheets of
bibulous paper. When dry the paper is highly transparent.
IV. APPLICATION OF PHOTOGENIC DRAWING.--This method of photogenic
drawing may be applied to useful purposes, such as the copying of
paintings on glass by the light thrown through them on the prepared
paper--Imitations of etchings, which may be accomplished by covering a
piece of glass with a thick coat of white oil paint; when dry, with the
point of a needle, lines or scratches are to be made through the white
lead ground, so as to lay the glass bare; then place the glass upon a
piece of prepared paper, and expose it to the light. Of course every
line will be represented beneath of a black color, and thus an
imitation etching will be produced. It is also applicable to the
delineation of microscopic objects, architecture, sculpture, landscapes
and external nature.
A novel application of this art has been recently suggested, which
would doubtless prove useful in very many instances. By rendering the
wood used for engravings sensitive to light, impressions may be at once
made thereon, without the aid of the artist's pencil. The preparation
of the wood is simply as follows:--Place its face or smooth side
downwards, in a plate containing twenty grains of common salt dissolved
in an ounce of water; here let it remain for five minutes, take it out
and dry it; then place it again face downwards in another plate
containing sixty grains of nitrate of silver to an ounce of water; here
let it rest one minute, when taken out and dried in the dark it will be
fit for use, and will become, on exposure to the light, of a fine brown
color. Should it be required more sensitive, it must be immersed in
each solution a second time, for a few seconds only. It will now be
very soon effected by a very diffused light.
This process may be useful to carvers and wood engravers not only to
those who cut the fine objects of artistical design, but still more to
those who cut patterns and blocks for lace, muslin, calico-printing,
paper hangings, etc., as by this means the errors, expense and time of
the draughtsman may be wholly saved, and in a minute or two the most
elaborate picture or design, or the most complicated machinery, be
delineated with the utmost truth and clearness.