H Cooper's Process 1865





PREPARATION OF THE PAPER

St. Vincent arrowroot 200 grains

Boiling water 10 ounces



Crush the arrowroot to fine powder, then rub it to a paste with a little

water, and let an assistant pour a few drams of boiling water while you

keep stirring all the time; finally, let him add the rest of the boiling

water, the operator still continuing the stirring. The paste is allowed

to cool, and will be thicker when cold than when hot. Remove the upper

portion entirely when quite cold, otherwise, if any left, it will give

rise to streaks. The author insists upon the necessity of all these

cares. Two sheets of paper are now placed side by side on a flat board,

then the surface of the first is covered with the paste by means of a

sponge, proceeding, before you leave it, all over the sheet in a

horizontal direction; the second sheet is covered in a like manner. By

the time the second sheet is pasted, the first one will be partially dry.

The sponge is now drawn over each sheet, in succession, in a perpendicular

direction in order to efface the streaks from the first sponging. If the

paste drags in a slimy manner, it is too strong, and a fresh arrowroot

must be prepared, because dilution only ends in failure. Why dry, the

paper is rolled under moderate pressure, and when it lies smoothly the

maximum pressure may be applied.



PLAIN COLLODION.

Alcohol 12 ounces

Ether 4 ounces

Pyroxyline 80 grains



SENSITIVE COLLODION.

Plain collodion 1 ounce

Nitrate of uranium, pure 30 grains

Nitrate or silver 5 grains



Add the uranium first, and as soon as it has dissolved all that it can,

add a grain or two of soda, and when settled pour off the supernatant

collodion and add the silver.(14) To coat the paper with collodion, use a

board with a handle beneath, such as is used by plasterers. On this place

a sheet of paper, the edges being turned up about the sixteenth of an

inch; this enables the whole of the sheet to be covered without spilling

the collodion or allowing it to run on the back of the paper.



There is a marked difference in the appearance of the prints when they

leave the pressure frame. Some samples of collodion cause the picture to

print of a beautiful green, others of a rich brown, and some of a yellow

or orange tint. The last take the longest of all to tone, and difficultly

assume the tint of well toned silver prints,(15) those printing to green

or brown tone very rapidly.



After printing the pictures are placed in diluted sulphuric acid, 1 to 30

of water, until the high lights are perfectly clear and white; this takes

from ten to fifteen minutes. After washing well under a stream of water,

they are placed in the toning and fixing bath.



TONING AND FIXING BATH.

Sulphocyanide of ammonium 1 ounce

Water 12 ounces

Chloride of gold 1 to 3 grains



After removing from this bath, the prints are immersed for a few moments

in water, and then rapidly washed.



FORMULA FOR PREPARING THE PYROXYLINE

Nitric acid, sp. gr. 1.30 12 fluid ounces

Sulphuric acid, sp. gr. 36 fluid ounces

1.845

Water 8 fluid ounces

Temperature 130 degrees Fahr.

Time of immersion 15 minutes.





Guarbassi's Process 1867 Houdoy's Process 1858 facebooktwittergoogle_plusredditpinterestlinkedinmail

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