when large sizes or large numbers of prints are required. For large
sizes the negatives are reversed in the process of enlargement. For
small sizes one or more reproduced reversed negatives are made,
either in the camera from a carbon transparency, or by contact
printing from a carbon transparency on a dry plate. With reasonable
care, little if any loss of quality occurs in reproduction. As the
single transfer process is the most simple form of carbon printing,
it is generally recommended to beginners. Probably the most simple
form of all is single transfer on opal. The opal plate does not
require any preparation beyond cleaning. Neither soap nor grease of
any kind must be permitted to contaminate the surface, otherwise the
print will fail to adhere. Opal plates are cleaned by scrubbing with
fine graining sand and water, and a muller or a small plate, either
of ordinary or opal glass, placed upon the wetted sand and moved
over the surface with a circular motion until soiled or discoloured
markings are ground off.
THE ACTINOMETER.
An actinometer must be used to gauge the amount of exposure, as only
a faint image, and in some tissues none at all, is visible during or
after exposure. The simplest form of instrument is the best. That in
general use is known as Johnson's Actinometer, a square tin box
containing a long strip of sensitive albumen paper, and provided
with a glass lid painted to the colour of printed albumen paper, an
opening in the paint in the form of a slit three-sixteenths of an
inch in width, from which the paint has been removed. The strip of
sensitive paper is made to pass between the top of an inner lid and
the painted side of the glass lid underneath the clear slit with the
end of the strip protruding at one side of the box. On exposure to
light the sensitive silver paper gradually discolours until it
closely resembles the colour of the paint, that is called one tint;
the tint is changed by pulling the slip forward just the width of
the slit, and so on until the requisite number of tints have been
printed for the strongest or densest negative in the batch exposed,
those negatives requiring less exposure are turned down or removed
when the requisite number of tints are registered in each case.
EXPOSURE.
For double transfer from opal the materials required are opal
plates, sensitive tissue, French chalk, collodion, double transfer
paper, pressure frame, flat camel-hair brush, chamois leather.
Before placing the negative in pressure frame, carefully clean from
both sides all finger marks, etc., with the leather, place negative
in frame on a paper mask, or provided with a safe edge. After
exposure to light, remove from frame and develop on plate prepared
as follows:--Rub the whole surface with French chalk on a pad of
muslin, afterwards removing loose particles by gentle brushing. Coat
with collodion made as follows:--Enamel collodion, 1 part; ether, 1
part; alcohol, 1 part. Filter and coat by pouring a pool on centre
of the plate, and, by tilting it, force the collodion to flow into
the top right corner, then to the left, then to bottom left, and
finally drain off at bottom right corner, rocking the plate the
while. The collodion must be allowed to set until it will bear the
gentle pressure of a finger in its thickest part, but must not be
permitted to dry in any part before plunging into clean cold water
to remove the solvents by washing. The time required in washing is
variable according to time of year. When the collodion ceases to
repel water it is ready to receive the printed tissue. Soak the
tissue for the requisite time, but not so long as to become quite
saturated, bring it into contact with collodionized side of plate,
remove to squeegeeing board, place over it a piece of wet rubber
cloth, or a piece of wet thick single transfer paper, coated side
up, to prevent injury to exposed margin of collodion and to
facilitate the smooth passage of squeegee over the surface in
removing excess of water. If, on removing the covering from the
plate, the back of tissue is found to be unevenly wet, blot or place
plate in a rack to drain; in a few minutes develop in warm water,
temperature 90° to 100° F. Be careful to remove the backing paper
_under water_, _and as soon as possible after immersion_ in the warm
bath. Finish development by laving or pouring warm water over the
print from jug or other vessel, until all details are brought out.
When washing is finished the print should look rather light, as in
drying a decided increase in strength is obtained; rinse _slightly_
in alum solution to stop bleeding only, place in clean cold water to
wash out any remains of bichromate, thoroughly rinse by dashing
water upon the print to remove any particles of solid matter that
may have stuck to its surface; place in a rack to dry, and transfer
as soon after drying as possible. The transfer paper is cut a trifle
larger than the net size of the print, but less than the opal
support; it is soaked in warm water until the surface is slimy to
the touch, but not soft enough to break under pressure between
finger and thumb. The softened transfer paper is placed in clean
cold water into which the dry print is plunged, water dashed upon
its surface to remove air; the two surfaces are brought into contact
under water, and squeegeed into contact as in first mounting before
development. When thoroughly dry, the print may be removed from the
opal plate by inserting the point of a knife at the edge.
Double transfer prints with enamelled surface are produced precisely
as above, only substituting patent plate for ground opal, and by
adding a second thickness of paper to the back of the finished print
before removal from its temporary support.
DOUBLE TRANSFER FROM FLEXIBLE SUPPORT.
The flexible temporary support is prepared by waxing. The waxing
solutions are:--
No. 1.
Benzol 1 oz.
Pure beeswax (natural not bleached) 3 grs.
No. 2.
Turpentine 1 oz.
Yellow resin 10 grs.
After dissolving, mix the two solutions, pour a little of the
mixture on fine flannel, rub it over so as to evenly moisten the
surface of the flexible support, wipe off with a second flannel
using only slight pressure but rubbing briskly and with circular
_motion_. When finished, the waxed surface should be perfectly even
and quite free from streaks or other markings. The waxing should be
done some considerable time before the support is required for use,
and exposed to the free action of air to remove all trace of the
solvents.
PAPER PRINTS WITH ORDINARY OR SLIGHTLY GLAZED SURFACE.
After removal from the pressure frame, the tissue is plunged into
cold water with a piece of support slightly larger. After soaking
the necessary time, the prepared surfaces are brought into contact
under water, removed from the bath and placed upon any even plane
surface, such as zinc, glass, etc., squeegeed into contact, blotted
or otherwise treated to remove uneven dampness, and developed in
warm water as in double transfer from rigid support, then slightly
rinsed in alum solution and washed in clean cold water until all
traces of bichromate are removed. After the transferring is done as
before described, only the print on flexible support must be soaked
in water until quite flat before bringing into contact with its
final support.
PAPER PRINTS WITH HIGHLY GLAZED SURFACE.
The printed tissue after removal from the pressure frame is coated
with collodion, for this coating allowance must be made in printing.
A considerable reduction in temperature takes place and any moisture
present in the air is condensed on the tissue, bringing into action
the well-known effect of continued moisture, _i.e._, considerably
increasing the depth of the print. Great care must be taken to coat
evenly and to prevent the collodion running in streaks on the back
of the print. When such streaks or unevenness of any kind are
present, a corresponding dark line or lines will be found on the
face of the finished print. Transfer same as for prints with
ordinary surface. All prints from flexible support on paper with a
highly glazed surface as well as those intended for transfer to
ivory or opal are coated with thin collodion:--
Enamel collodion 2 parts
Ether 4 "
Alcohol 4 "
DOUBLE TRANSFER TO OPAL AND IVORY.
After development the print is allowed to dry, and as soon after
drying as possible it is transferred to its final support, whether
opal or ivory, by a solution of gelatine composed of the following
ingredients:--
Gelatine (fairly hard) 1-1/2 ozs.
Water 20 "
Chrome alum solution (30 grs.) 2 "
Soak the gelatine in the water until quite limp, dissolve by heat,
then add the 30 grain chrome alum solution; roughly filter through
two or more thicknesses of fine muslin into a flat dish on a water
bath. After cutting the print to a size a trifle less than opal or
ivory, place both print and final support in gelatine solution,
allow print to stretch until quite flat, then bring them into
contact under solution, squeegee and place on edge to dry. When
quite dry, remove temporary support by inserting the point of a
knife between the surfaces at the edge, wash with benzol or ether to
remove all traces of the waxing solution. The print is now ready for
the artist.
DOUBLE TRANSFER PRINTS ON CANVAS.
For double transfer prints on canvas, as a basis for oil painting,
there is not at the present moment a large demand. A strong
prejudice exists, and deservedly so, against such prints, for the
following reasons. Some thirty years ago, in the principal
establishment in which carbon work was done, a process of printing
on canvas was in vogue. It was roughly this:--A stretched artist's
canvas without other preparation was coated with dammar varnish;
after drying, the canvas was used in pretty much the same way as
single transfer paper is now--that is to say, a piece of printed
tissue was squeegeed into contact with its surface, developed by
floating on hot water, and practically in that crude condition
placed in the hands of artists for oil-colour painting or finishing
as it is sometimes prudently called. The natural result
followed--_viz._, in a dry warm room the canvas stretched, the film
of unmodified gelatine contracted; hence cracks, peeling, etc.,
until the work, valuable or otherwise, was utterly ruined. The
method of preparing the canvas for the reception of the carbon image
introduced by the writer is based upon opposite principles, as
mentioned in the preceding general remarks, and may be described as
follows:--A yielding and elastic substratum of gelatine forms a
crust, so to speak, that expands and contracts according to the
corresponding behaviour of the canvas support.
Ordinary painted canvas, such as is used by artists, or strong linen
may be used with special treatment.
PREPARATION OF PAINTED CANVAS.
The canvas is first stretched tightly on a drawing board, same size
as picture required, the greater part of paint removed by scrubbing
with soda solution (either nail brush, sponge or a piece of flannel
will answer the purpose) until the surface of the fabric is exposed
and little of the paint remains beyond the priming. After drying,
the canvas is coated with the following solution, applied with a
flat camel-hair brush. Several coats (three in cold, four in warm
weather) are given, drying between each and rubbing with fine sand
paper if at all uneven.
Coating Solution.
Cooking gelatine (Cox's soup answers perfectly) 4 oz.
Sugar 2 "
Glycerine 2 "
Water 30 "
30 grain chrome alum solution 1 "
The print is exposed in the ordinary manner, developed on temporary
support, allowed to dry and transferred to the canvas as
follows:--The canvas is placed face upwards, on a level surface by
preference, on a broad board over a large tank. The dry print is
placed face upwards in a flat dish, the warm coating solution poured
over it, air bells removed with the brush, the surface of the canvas
brushed over with the solution. The bulk of the solution is then
poured on the canvas and before it has had time to run off the print
is lowered carefully and quickly upon it and squeegeed to remove
excess of solution. After thorough drying, the temporary support is
removed, the surface of the print cleaned with benzol or ether or a
mixture of both to remove every trace of the waxing compound, and
mounted on a stretcher in the usual manner. A print on canvas
prepared as above, is perfectly reliable, it will neither crack nor
peel, and can be used with perfect confidence as a basis for the
most costly form of artistic finishing, as the carbon image rests
upon an elastic substratum in actual contact with the fibrous
substance of the canvas.
TO PREPARE ORDINARY STRONG LINEN OR CALICO.
Proceed precisely as for painted canvas (of course without
scrubbing), using the same coating solution with half-a-pound white
pigment added, sulphate of baryta answers perfectly. Sand or glass
paper must be used pretty freely as the surface of the unpainted
fabric washes up roughly when the gelatine coatings are applied.
WOOD PANELS.
Wood panels are prepared by removing the surface of the paint only
with soda solution. After drying, a tooth is given by rubbing with
fine sand paper and coating with solution as under:--
Gelatine (Cox's soup) 3 oz.
Sugar 1 "
Glycerine 1/2 "
Water 30 "
30 grain chrome alum solution 3/4 "
_Note._--Before transferring to either kinds of canvas or wood panel
in cold weather, it is absolutely necessary to thoroughly warm the
final support, otherwise the gelatine solution will gelatinize
before the excess can be removed from between the surfaces.
THE SINGLE TRANSFER PROCESS.
The single transfer process may be briefly described as
follows:--The sensitive tissue is exposed under a negative and the
exposure gauged by actinometer as for double transfer printing.
After removal from the pressure frame the printed tissue is plunged
into clean cold water along with a piece of transfer paper of any
desired surface or quality, cut a little larger than the tissue (to
provide a margin by which the picture may be handled without injury
during development). After soaking the requisite time, the two
prepared surfaces are brought into contact under the water, removed
to a squeegeeing board, plate of glass or zinc, and squeegeed into
contact; care must be taken to use only as much pressure as is
needed to remove the superfluous water from between the surfaces. A
sponge may be used instead of a squeegee, or both may be dispensed
with, if care is taken to remove every trace of air from surfaces
before lifting from the cold water bath. When neither squeegee or
substitute for it is used, the print must be handled with greater
care, as undue bending before atmospheric pressure comes into
operation would destroy contact. The print is hung up to drain, and
more time allowed between mounting and development. Development is
the same as in double transfer, with one or two rather important
exceptions. 1st. The single transfer print is developed upon the
material on which it is to remain. 2nd. There is no preparation of
the supports, neither in the case of paper or opal. 3rd. The
developed print can be soaked for a considerable time in a saturated
solution of alum without injury, the alum solution greatly assisting
in removing bichromate.
CARBON TRANSPARENCIES.
Carbon transparencies, either for projection, enlargement, or
reproduction, are printed in a special tissue known as transparency
tissue, and developed on glass plates prepared with a thin coating
of fine hard gelatine. The coating solution is composed as
follows:--
Gelatine 3/4 oz.
Water 40 "
Bichromate potash 1 dram.
The glass plates are carefully selected, free from bells, scratches,
and other defects; thoroughly cleaned, either by acid or rubbing
with plate powder to remove every trace of grease, and then coated
with the gelatine solution, and placed in a rack to dry; when dry,
exposed to light to render the film somewhat insoluble. It is not
desirable to print until the film is absolutely hardened throughout.
The print adheres firmly to the plate when the substratum is not
over-printed.
A positive intended for projection should show clear glass in the
highest lights without undue density in the shadows, all details
plainly seen--in a word, quite transparent.
Positives intended for enlargement must be fully exposed--that is to
say, every detail on the highest lights brought out, but no more;
beyond that point there is nothing to be gained. Over-printing in
the transparency tends to bury detail in the shadows of the enlarged
negative, and to blend the highest grades in the high-lights,
reducing the roundness or modelling of the picture.
In the case of very hard negatives intended for enlargement, the
usual treatment is to sun the whole surface of the transparency in
order to secure detail in the high-lights. A moment's consideration
will convince any practical printer that nothing but injury to the
final print can result from such treatment of the transparency. The
high-lights are degraded, the details in the shadows further buried.
The better method is to make an extra special transparency tissue,
for the printing of such hard negatives, containing a greatly
reduced proportion of pigment to gelatine. Such a tissue permits
greater depth of printing, retains all details in the shadows and
high-lights, and, in fact, enables the enlarger to produce a
negative that will yield a thoroughly satisfactory print.
REPRODUCED NEGATIVES.
In making reproduced negatives from hard originals, ordinary
transparency tissue will serve every purpose. The transparency is
printed in the usual way, and developed on a prepared glass plate;
when dry a negative is printed from the transparency without special
treatment and also developed on glass, when a decided reduction of
density will be found to have taken place. The reproduced negative
will possess all the good qualities of the original, plus improved
printing quality. It is only in the case of extremely hard negatives
that the extra special tissue is required.
If a perfect reproduction of an original negative is required, the
transparency must be printed either in very weak light or in direct
sunlight. Either method gives a brighter image than that produced in
ordinary diffused daylight. The same method must be adopted in
printing the negative.
_Note._--Care must be taken when direct sunlight is used to see that
the pressure frame and everything in and about it is thoroughly dry,
otherwise the tissue may stick to the negative, spoiling the print
and probably the negative also. It must also be noted that two
tints, printed in direct sunlight, although of apparently the same
depth, mean quite as much as three such tints printed in diffused
light.
FAILURES AND DEFECTS: THEIR CAUSES AND CURE.
As a rule, failures in working the carbon process are caused, as in
most other cases of failure, by imperfect _knowledge of the
substances and nature of the ingredients used in the process_.
Before going into further detail, it may be as well to point out
that a great deal of misunderstanding has been caused, by writers on
this subject--that may be fairly termed "blind leaders of the
blind." With only slight knowledge of the subject they have misled
beginners by assuring them that the process is simplicity itself, in
fact the most simple photographic printing process extant. Up to a
certain point, and to that certain point only, is such description
true. There are no subtle chemical combinations, no mixing and
maturing of toning or other solutions. But--and in this case there
is great virtue in the _but_--the greatest care is not only
required, it is absolutely demanded, in manipulation. A carbon print
from start to finish is probably subject to more chances of injury
than any other form of print in existence. When this fact has been
fully grasped by the novice, and he has been thoroughly prepared for
the difficulties before him, the rest is plain sailing. Care, and
care only; nothing beyond. He who wishes to succeed in carbon work
must pay infinite attention to every small matter of detail as far
as such detail relates to manipulation, otherwise he will only
succeed in achieving failure.
FRILLING AND RETICULATIONS.
Frilly reticulations are generally caused by over-soaking the tissue
before development, or failing to provide protection of the clear
portions of the margin of the negative by a safe edge.
SPOTS ON THE FINISHED PRINT.
Spots are generally caused by solid particles of grit or other
impurities being allowed to find their way into the water in the
process of development, or, as in the case of certain peculiar
circular spots that often deface the carbon print, such spots are
caused by small fragments of tissue broken from the edges in
cutting, which, being of the same colour as the prepared surface of
the tissue and exceedingly small, often escape notice. They adhere
most tenaciously to the surface of the tissue, and if not removed
before the print is mounted upon its temporary or final support,
cause the mischief referred to; being confined between two surfaces
they cannot escape, but are dissolved by the water used in
developing the print, swell and make a circular patch, often greatly
injuring the picture.
Spots of a different character are produced in quite an opposite
direction. Instead of being black they are light, in groups each
spot having a dark rim on the outside. They generally occur in
under-exposed prints, and are formed by fine particles of air
imprisoned between the coating of gelatine and the paper support.
When the tissue is mounted for development and placed in warm water,
the fine particles of air swell, and not being able to escape from
between the surfaces, impress themselves into the yielding portions
of the printed tissue and make the marks above referred to, unless
the printing has been deep enough to allow of their removal before
development is completed.
CAUSE OF FAILURES IN THE SECOND TRANSFER.
Other causes of failure refer particularly to prints by double
transfer, either to paper, opal, ivory, canvas or wood panel or any
similar surfaces.
Such failures are generally produced by _soap_, _fat_, or _any kind_
of greasy substances being permitted to find their way into the
water in which such prints have been manipulated previous to their
final transfer. Another point should be mentioned: the sooner a
print intended for second transfer is finished the better the result
will be.
PRESSURE MARKS.
Pressure marks are caused by using damp tissue or damp pads in the
pressure frame. It is recommended that a piece of waterproof
material, such as mackintosh cloth, be placed between the tissue and
the padding, and that the pads be as smooth and free from grain as
possible. It will be found on close examination that the mottled,
spotty appearance, known as pressure marks, closely resemble the
texture of the pads behind the tissue.
_Thos. S. Skelton._
INDEX.
=A.=
Alpine Photography, 9
" Outfit for, 9
" Lens for, 10
" Carrying camera in, 12
" Plates for, 14
" Carrying Baggage for, 15
" Outfit for Developing, 16
" Exposures, 17
" Development, 18
" " Formulæ, 20
" Light (tables), 21, 22
Accelerator, 24
Alum Bath, Formula, 41
Aberration, Spherical, 60
" Chromatic, 61
Astigmatism, 62
Aplanat Lens, 64
Astigmat Lens, 64
Aperture of Lens, 68
Angle of Image, 70
Accessories in Portraiture, 79
Architectural Photography, 117
" " Camera for, 118
" " Lenses for, 119
" " Plates for, 122
Actinometer for Platinotype, 208
" for Carbon Process, 271
=B.=
Backing Mixtures, 49
Background in Portraiture, 78
Breadth in Pictorial Work, 93
Blisters on P.O.P, 194
Bromide Printing, 225
" Safe light for, 226
" Negative for, 227
Bromide Paper, sensitive side of, 227
" Printing, 232, 233, 227
" " Lamp for, 228
Bromide Printing, masks and discs, 230
" " Vignetting, 231
" " Cloud Printing, 231
Bromide Paper, development of., 233
" " Iron developer for, 234
" " Metol, 235
" " Hydrokinone for, 236
" " Eikonogen for, 236
" " Clearing Bath, 235
" " Fixing Bath, 235
Bromide Prints, toning with gold, 237
" " Toning with Uranium, 238
" " Intensifying, 238
" " Reducing, 239
" " Cheap Trays for, 240
=C.=
Camera, Carrying in Alps, 12
Caramel for Backing, 49
Curvature of Field of Lens, 62
Cooke Lens, 65
Composition in Pictorial Work, 95