This process consists in converting a cliche in half tones into one in

lines, which can be directly printed on paper, or impressed, by means of

an ink transfer made as explained before, on a stone, or on a zinc or

copper plate for etching in relief, or in intaglio, according as the

cliche is negative or positive.

A cliche on gelatine, but preferably on a collodion film, is varnished

with a solution of yel
ow wax and bitumen in benzole and turpentine-oil:

Bitumen of Judaea 8 parts

Yellow wax 2 parts

Benzole 40 parts

Turpentine oil 60 parts (filter)

then etched as done to engrave in the aquafortis manner, the corrections

being made by applying with a brush some of the above varnish on the

defective parts, which are worked over when the varnish is dry.

The tools are simply needles of various thickness ground in sharp square

and round points of different sizes.

When the etching is finished, the parts which should form the ground, or

white parts of the design, being covered with the bitumen varnish is

non-actinic, or, in other words, does not admit the light acting on the

sensitive plate preparation employed to reproduce the design, except by an

exposure a good deal longer than that necessary to reduce the metallic


The engraver will see at once that, although it greatly simplifies the

copying work and, consequently, saves much time, this process does not,

however, bind him to any rules and leaves him perfectly free to follow its

inspirations and make such alterations as he thinks proper to produce

artistic effects; in a word, the reproduction will no more be a picture

taken by a mechanical process, so to say, but an original drawing

reflecting his talent and characteristic manner.

A similar process much employed by photo engravers, and presenting the

same advantages, is to convert an ordinary photograph on paper--or a blue

print, as devised by the writer--into a design in lines by drawing with

India ink, or the special ink of Higgins, and, this done, to wash off the

photographic image, the design being afterwards reproduced by the ordinary

processes as a negative or a positive cliche.

When the photograph is a silver print especially made for the purpose in

question and, consequently not toned, but simply fixed in a new

thiosulphate (hyposulphite) bath, and well washed--it is bleached by

flowing over a solution of--

Bichloride of mercury 5 parts

Alcohol 40 parts(13)

Water 100 parts

If the photograph has been toned, i.e., colored by a deposit of gold, or

if it was fixed in a thiosulphate bath in which toned prints have been

fixed, then the image is dissolved by treatment in a solution of potassium

cyanide in alcoholized water.

When a blue photograph is reduced, it is advisable before drawing upon it

to first reduce its intensity by a prolonged immersion into water. Pale

blue is a very actinic color which is not reproduced in photography,

except by the ortho-chromatic process, or if it does, the impression being

very weak, is not objectionable. When the image has not been sufficiently

or not at all bleached, the blue is dissolved by an alcoholized solution

of the blue solving.