Daily Yellowstone journal. [volume] (Miles City, Mont.) 1882-1893, 1885-07-26
PH0TO-MECHANICAL
PROCESSES OF PREPARING ILLUS
TRATIoNs FOR BOOKS.
[Scientlfc American. ]

Scientific Americana
The artotype is made In the following
manner: A plate. preferably of glass. Is
carefully coated with a solution OF gela'
tine containing bichromate Of potash. II
Ia then dried, and an ordinary photo.
graphic negative is placed in contact with
it and exposed to the action Of light.
which hardens all the parts correspond.
ing with the transparent parts Of the ne {.
alive or the dark parts OF the picture
After the proper exposure. the plate is
washed in cold water 10 remove all the
sensitzing material, and 1t is then dried
The gelatine surface will be found &c
have changed, so that 1t will act pre-
cisely Ike photographic stone; when
moistened. the parts that were protected
from light by the opaque parts of the
negative absorb water, while other parts
remain dry.
A roller charged with fatty ink is rolled
over the plate, the ink adhering to the
dry parts and being rejected by the parts
that have absorbed water Paper is now
placed on the linked surface and subjected
10 pressure, when the design will be
transferred TO the piece of paper Then
the moistening linking. aud pressure are
repeated until the required number OF
copies has been produced
The photngravure process takes plate,
and covers ii with a solution of bichro.
mated gelatine containing fine powder
TO give it grain. This is exposed to light
through negative, Just as is done in
making artotypes Then Il Is washed
In hot water. which dissolves all
the gelatine that was not affected by
the light carrying with il the fine
oowder, and which leaves the gelatine
with the grain in all the dark parts Of
The picture. The plate is now dried and
placed IN an electro.plating bath, or an i'm.
preston IN wax is made FROM the gela.
tine plate and then placed in an electro.
plating bath. Copper is deposited until
sufficiently thick. when the plate Is re-
moved and put in.O the hands Of an en-
graver, who repa rs all the imperfections
and makes any other desired changes with
the BURN.
Impressions are taken from the plate
In the same manner as any copper OF
steel plate engraving is done. The cost OF
printing photographers is very nearly the
same as that Of printing artotypes, but the
photogravure plate costs much more than
The artotype plate. and unless the edition
required is very large. the plate alone
will cost more than the complete edition
IN artotype
In Brauu's reproductions paper is COW
cred with gelatine containing India ink,
lampblacS, or any other desired pigment,
until The whole surface Ia thickly coated,
when Il Is dried In making a picture,
this prepared paper Is immersed IN a solu.
ton Of bichromate of potash for few
minutes and then dried in the dark. after
which II is exposed 10 light in contact
with negative. When sur Gent in.
ISOLATION has taken place, the paper
Is moistened aud pressed face down.
ward upon prepared glass plate.
After pressure Of several minutes the
glass and paper are put In hot water, dis.
solving the gelatine, and loosening the
paper, That the latter may lie stripped OFF
leaving the gelatine on the glass The
gelatine continues TO dissolve. until only
so much of 1t is left as has been sufii
GENTLY hardened by light to resist the so
lusion by the hot water when washed
away. until only enough Is left to form
the picture; the picture after drying is
transferred 70 paper, then finally mounted
on cardboard
The Woodburytype Is made by insolat.
tuk u scuoitiNS Bttdbiuc "
glass, washing the unchanged gelatne
away, and leaving only the parts that
form the picture. This, after being
dried is pressed mechanically into plate
of soft metal, making an intaglio, into
which Is cast a mixture Of hot gelatine
and any coloring matter. Paper is pressed
with tlst pressure and allowed
10 cool when the augmented gela
tine will be nrmly attached to
the paper, which is dried trimmed and
mounted The Woodburytype is adapted
only for pictures Of comparatively small
dimensions Brauns pictures and the
Moodburytypes have 70 be mounted: this
IL found to be OF great disadvantage in
using them for book illustrations. Both
are merely thin films Of gelatine. and
they cannot compare In permanency with
artOtypes. phologra' ures, and helioS'ay.
unes.