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Choice Of Paper Sizing








In all the photographic processes by precipitation of metallic oxides the
quality of the paper has a great influence on the results. When the paper
is not well sized and not well calendered, the sensitizing solution is
absorbed, instead of simply impregnating the surface of the paper, and not
only the image is sunk in and its sharpness impaired, but good whites can
never be obtained, especially if the image should be toned, owing to the
impossibility of eliminating the metallic salts not acted on, that is, not
reduced by the action of light which the fibers of the paper mechanically
retain.

The "endless" rolls of paper, 54: inches wide--or "blue print paper," as it
is sometimes termed--of Blanchet freres et Kleber, of Rives, better known
as "Rives' paper", that of Johannot, of Annonay (France), and the
Steinbach (Saxe) paper are recommended.

For small prints from negatives in half tone the positive paper, 18x22
inches, of Rives or Saxe, should be preferred to the heavy kind. It is
advisable to size it, so that the impressions be entirely formed on the
surface of the paper. Moreover, an additional sizing is always
advantageous, whatever be the photographic process employed, to prevent
the imbibition of the sensitizing compound and to obtain more brilliant
and vigorous images, for the iron, chromium, uranium and other metallic
soluble salts require the presence of an organic matter (alcohol, ether,
gum arabic, glucose, caseine, etc.) to be reduced by the agency of light;
and as a consequence, the greater, within certain limits, of course, the
amount of organic matters, and the more thoroughly they are mixed with the
salts, the more sensitive the preparation and the better the results.

Arrowroot is the best sizing for our purposes. Gelatine may be employed,
albumen also, but the coating should be insolubized when applied on the
paper and dry.

Sizing with Arrowroot.--In a porcelain dish diffuse 4 parts of powdered
arrowroot and one part of liquid glucose in 200 parts of distilled or rain
water and dissolve by heat over an alcohol lamp, stirring all the while.
Let the solution boil for an instant, and when the paste is homogeneous
let it cool down and then remove the skin formed on its surface and strain
it through a fine canvas. Now provide with three small sponges free from
gritty matters and cleaned in water, and nail by the four corners, one
over the other, felt size uppermost, as many sheets of paper as you wish
to size on a board somewhat smaller than the paper. This done, with one
of the sponges take a small quantity of the arrowroot and, brushing it
length-way and cross-way, spread the paste into an even layer, then, by
rubbing very lightly with the second sponge, efface the striae and smooth
the coating as well as possible. The third sponge serves to remove the
excess of paste when too much is at first spread on. From six to seven
sheets of paper, 18x22, can be sized with the quantity of arrowroot paste
above given.

Another, but not quite so effective a manner of sizing although sufficient
for the cyanotype, is the following, employed by Mr. Pizzighelli for the
paper used in the platinotypic process:

Ten parts of arrowroot are powdered in a mortar with a little water and
then mixed by small quantities to 800 parts of boiling water. After a few
minutes 200 parts of alcohol are added and the mixture filtered. The
paper is immersed for two or three minutes in the warm solution and hung
up to dry.

Sizing, with Gelatine.--Dissolve at a temperature of about 140 deg. Fahr.
(60 deg. C.) 10 parts of good gelatine in 800 parts of water, then add 200
parts of alcohol and 3 parts of alum dissolved in a little water. Filter
and prepare the paper by immersion as above directed. The gelatinized
paper when dry should be prepared a second time and dried by hanging it up
in the opposite direction in order to obtain an even coating.





Next: The Cyanotype Or Blue Process

Previous: How To Make A Negative Drawing



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