Printing On Wood Canvas Opal And Transparencies

Printing on Wood.--To print on a wood block a design to be engraved on

the same presents certain difficulties. In the first place, the

sensitizing solution must not be absorbed by the wood, but remain wholly

on its surface; then the photo film, although thick enough to produce an

image sufficiently intense to be distinctly visible in all its details,

should not scale or clip away under the graver, and not interfere in any
/> way with the work of the artist; the least touch of the graver must reach

the wood and make its impression. Lastly, the design should be permanent.

These difficulties will be avoided by adhering to the instructions given

in the lines following.

The solution to render impervious the surface of the wood consists of

Common gelatine 5 parts

Gum arabic 3 parts

Castile soap 3 parts

Water 100 parts

Dissolve by heat on a water bath.

To apply it, the wood is rubbed with fine sandpaper, then heated over a

spirit lamp to about 86 deg. Fahr. (30 deg. C.) and upon it is poured in

excess the liquefied and quite warm solution, which must be allowed to

penetrate in the pores of the wood by letting it gelatinize, when it is

wiped off clean. Nothing must remain on the surface of the wood. This

done, and while still damp, the preparation is rendered insoluble by

pouring over a solution of alum at 5 per 100 of water. The object of this

preliminary operation is to render the wood impervious, and therefore to

prevent the sensitizing solution to penetrate its texture. The wood is

then heated again and its surface whitened with a little silver white or

sulphate of barium, diffused in a small quantity of the following warm


Gelatine 1 parts

Alum 0.1 part

Water 100 parts

While wet, this is smoothed with a jeweler's brush, taking care to leave

on the wood, a very thin layer of the mixture, only sufficient to obtain a

white surface which, by contrasting with color of the wood assists the

engraver in his work. The wood should now be allowed to dry thoroughly,

when it is coated with a tepid solution of

Isinglass 3 parts

Water 100 parts

and dried.

Now the sensitizing process differs according as whether the cliche is

positive or negative. In the former case the preparation is sensitized

with the solution employed in the black process, proceeding afterwards as

usual; in the latter, that is, when the cliche is negative, the best

process is the cuprotype.(12)

For printing, special frames are employed to permit one to examine the

progress of the impression from time to time without the possibility of

either the wood block or the cliche moving. These frames open in two.

The upper frame is provided with screws on the four sides to hold firmly

the block when it is placed into contact with the cliche by means of the

screws fixed on the cross bars. As to the cliche, if it is made on a

glass plate, it is secured on the thick glass plate of the lower frame by

two wooden bars against it pushed by screws.

When the block is ready for printing, the prepared side is usually

concave. It is straightened by slightly wetting the back and resting it

on one end, prepared side against the wall.

Printing on Canvas.--The canvas should be first brushed with a solution

of aqueous ammonia in alcohol, 1:3, to remove greasiness until the thread

just commences to show, then, when rinsed and dry, rubbed with fine sand

to give a tooth, dusted, washed with a sponge and then coated with the

following solution, proceeding afterwards as in the cuprotype process:

Isinglass 8 parts

Uranic nitrate 5 parts

Copper nitrate 2 parts

Water 200 parts

Printing on Opal, Celluloid, etc., is quite simple; it suffices to coat

the material with the following gelatine solution, and, when the film is

dry, to proceed in operating by any one of the processes before described.

The sensitizing compound may be incorporated to the gelatine solution, but

we prefer not to do it and to sensitize the plates as they are wanted for


A. Gelatine 4 parts

Water 70 parts in volume

Dissolve and mix little by little in order:

B. Chrome alum 0.25 parts

Water, hot 20 parts

C. Alcohol 10 parts

When coated place the plates on a level stand until the gelatine is set,

and let them dry on a rack.

Transparencies.--Prepare the plate as directed above with

A. Gelatine 6 parts

Water 70 parts

B. Chrome alum 0.3 part

Water, hot 20 parts

C. Alcohol 10 parts

Sensitize with the uranic-copper solution employed in the cuprotype. By

this process transparencies of a rich brown, not actinic, color are

obtained. Consequently they can be used to reproduce negatives by the

same process. For lantern slides they may be toned black by platinic


To strip off the picture, apply, first, on the glass plate a substratum of

India rubber, 2 to 100 of benzole, coat with plain collodion, immerse the

plate in water as soon as the film is set, and when greasiness has

disappeared pour on the gelatine solution and proceed.

For tranferring on any material, a sheet of paper is immersed in a

solution of India rubber cement in 20 parts of benzole, dried, coated with

the gelatine solution, sensitized, etc., by operating in the ordinary

manner. After development, the proof, being dry, is brushed over with

alumed gelatine moderately warm, dried, immersed in tepid water until the

gelatine is softened and tacky, when it is placed on the material and

squeezed into contact. This done, the transfer should be allowed to dry

thoroughly. Now, by imbuing the proof with benzole to dissolve the India

rubber, the paper is easily stripped off, leaving behind the picture

adhering to the material.