One of the most extensive establishments for the purpose is that of
Messrs. Winter, in Vienna. They say to photographers in general: If
you will send us a portrait, either negative or positive, we will
produce you an enlargement on canvas worked up in monochrome. The
success of their undertaking lies in the circumstance that they do not
produce colored work--or, at any rate, it is exceptional on their part
to do so--but devote their efforts to the production of an artistic
portrait in brown or sepia. In this way they can make full use of the
dark brown photograph itself; there is less necessity for tampering
with the enlarged image, and natural blemishes in the model itself
maybe softened and modified, without interfering much with the true
lines of face and features. The monotone enlargements of Messrs.
Winter, again, exquisitely as most of them are finished, do not appear
to provoke the opposition of the painter; they do not cross his path,
and hence he is more willing to do them justice. Many a would-be
purchaser has been frightened out of his intention to buy an
enlargement by the scornful utterance of an artist friend about
"painted photographs," and in these days of cheap club portraits there
is certainly much risk of good work falling into disrepute. But a
well-finished portrait in monotone disarms the painter, and he is
willing to concede that the picture has merit.
"We cannot use English canvas, or 'shirting,' as you call it," said
one of our hosts; "it seems to contain so much fatty matter." The
German material, on the other hand, would appear to be fit for
photography as soon as it had been thoroughly worked in hot water and
rinsed. Here, in this apartment, paved with red brick, we see several
pieces of canvas drying. It is a large room, very clean, here and
there a washing trough, and in one corner two or three large
horizontal baths. The appearance is that of a wash-house, except that
all the assistants are men, and not washerwomen; there is plenty of
water everywhere, and the floor is well drained to allow of its
running off. We are to be favored with a sight of the whole process,
and this is the first operation.
Into one of the horizontal baths, measuring about 5 by 4 feet, is put
the salting solution. It is a bath that can be rocked, or inclined in
any direction, for its center rests upon a ball-and-socket joint. It
is of _papier mâché_, the inside covered with white enamel. Formerly,
only bromine salts were employed, but now the following formula is
adopted:
Bromide of potassium................... 3 parts.
Iodide of potassium.................... 1 part.
Bromide of cadmium..................... 1 "
Water................................ 240 parts.
Four assistants are required in the operation, and the same number
when it comes to sensitizing and developing, all of which processes
are commenced in the same way. The bath is tilted so that the liquid
collects at one end, and near this end two assistants hold across the
bath a stout glass rod; then the canvas is dipped into the liquid, and
drawn out by two other assistants over the glass rod. In this way the
canvas is thoroughly saturated, and, at the same time, drained of
superfluous liquid.
The canvas is hung up to dry; but as sometime must elapse before this
particular piece will be ready for sensitizing, we proceed with
another canvas which is fit and proper for that process. The room, we
should have mentioned, is provided with windows of yellow glass; but
as there is plenty of light nevertheless, the fact hardly strikes one
on entering. The sensitizing, with a solution of nitrate of silver, is
conducted with a glass rod in the same way as before, the solution
being thus compounded:
Nitrate of silver........................ 4 parts.
Citric acid.............................. 1 part.
Water.................................. 140 parts.
Again the canvas is dried, and then comes its exposure.
This is done in a room adjoining. We lift a curtain and enter a space
that reminds one of the underground regions of a theater. There are
curtained partitions and wooden structures on every hand; dark murky
corners combined with brilliant illumination. Messrs. Winter use the
electric light for enlarging, a lamp of Siemens' driven by a six-horse
power engine. The lamp is outside the enlarging room, and three large
lenses, or condensers, on three sides of the light, permit the making
of three enlargements at one end at the same time. (See Fig.)
[Illustration]
The condenser collects the rays, and these shine into a camera
arrangement in which the small negative is contained. The enlarged
image is then projected, magic lantern fashion, upon the screen, to
which is fastened the sensitized canvas. The screen in question is
upon a tramway--there are three tramways and three screens in all, as
shown in our sketch--and for this reason it is easy to advance and
retire the canvas, for the purpose of properly focusing it.
Even with the electric light now employed, it is necessary to expose a
considerable time to secure a vigorous impression. From ten minutes to
half an hour is the usual period, determined by the assistant, whose
experienced eye is the only guide. We should estimate the distance of
the cameras from the enlarging apparatus to be about fourteen or
fifteen feet in the instance we saw, and when the canvas was taken
down, a distinct outline of the image was visible on its surface.
By the way, we ought to mention that the canvas is in a decidedly limp
state during these operations. It has just sufficient stiffness to
keep smooth on the screen, and that is all; the treatment it has
received appears to have imparted no increase of substance to it.
Again it is brought into the red-brick washing apartment, and again
treated in one of the white enameled baths as before. This time it is
the developer that is contained in the bath, and the small limp
tablecloth--for that is what it looks like--after being drawn over the
glass rod, is put back into the bath, and the developing solution
rocked to and fro over it. The whiteness of the bath lining assists
one in forming a judgment of the image as it now gradually develops
and grows stronger. Here is the formula of the developer:
Pyrogallic acid......................... 10 parts.
Citric acid............................. 45 "
Water...................................410 "
The developer--which, it will be noted, is very acid--is warmed before
it is used, say to a temperature of 30° to 40° C.; nevertheless, the
development does not proceed very quickly. As we watched, exactly
eight minutes elapsed before Mr. Winter cried out sharply, "That will
do." Immediately one of the assistants seizes the wet canvas, crumples
it up without more ado, as if it were dirty linen, and takes it off to
a wooden washing trough, where it is kneaded and washed in true
washerwoman fashion. Water in plenty is sluiced over it, and after
more vigorous manipulation still, it is passed from trough to trough
until deemed sufficiently free from soluble salts to tone. The
toning--done in the ordinary way with gold--removes any unpleasant
redness the picture possesses, and then follows the fixing operation
in hyposulphite. As canvas is more permeable than paper, these two
last processes are quickly got through.
The final washing of the canvas is very thorough. Again it is treated
with all the vigor with which a good laundry-maid attacks dirty linen,
the canvas, in the end, being consigned to a regular washing-machine,
in which it is systematically worked for some time.
When the canvas picture at last is finished, it presents a very rough
appearance, by reason of the tiny fibers that stand erect all over the
surface. To lay these, and also to improve the surface generally, the
canvas is waxed, the fabric is stretched, and a semi-fluid mass rubbed
into it, heat being used in the process, which not only gives
brilliancy, but seems also to impart transparency to the shadows of
the picture. The result is a pleasant finish, without vulgar glare or
glaze, the high lights remaining beautifully pure and white.
Of course, the price of these canvas enlargements varies with the
amount of artistic work subsequently put upon them; but the usual
charge made by Messrs. Winter for a well-finished life-size portrait,
three quarter length, is sixty florins, or about £5 sterling as the
exchange now stands. Besides working for photographers, Messrs. Winter
are reproducing a large number of classic paintings and cartoons by
photography on canvas in this way (some of them almost absolutely
untouched), and these, as may be supposed, are finding a very large
sale among dealers. Such copies must necessarily be of considerable
value to artists and collectors, and altogether it would seem that
Messrs. Winter have hit upon a novel undertaking, which bids fair to
make them a handsome return for the outlay (large as it undoubtedly
has been) made upon their Vienna establishment.--_Photo. News._
* * * * *
DETECTION OF STARCH SUGAR SIRUP MIXED WITH SUGAR-HOUSE
MOLASSES.[1]
[Footnote 1: A Paper read before the American Chemical Society,
September 2, 1881.]