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Towler, John. The Silver Sunbeam. Joseph H. Ladd, New York: 1864. Electronic edition prepared from facsimile edition of Morgan and Morgan, Inc., Hastings-on-Hudson, New York. Second printing, Feb. 1974. ISBN 871000-005-9

Chapter XXXIII.
BERTRAND'S NEW PROCESS FOR POSITIVE PRINTING.

SAXONY paper is the best for this process; the equality of the mass is not absolutely necessary, but that which contains iron stains must be rejected.

The first preparation of the paper is to impregnate it with a soluble chloride; this is effected by plunging it into the following bath

Alcohol, spec. grav., .842, 100 parts.
Benzoin, 10
Chloride of cadmium, 5 "

The paper maybe floated on the surface or completely immersed. The most expeditious means is to take a dozen sheets and immerse them one by one in the bath, by means of a glass triangle; when a certain quantity has been immersed, they are all turned over at once, and then taken out one at a dine and hung up to dry; take care to place a piece of blotting-paper in contact with the lowest corner of each, in order to produce an accumulation of fluid in this place.

The sheets dry very quickly; a few minutes are sufficient. If necessary, they may be dried by artificial heat.

The advantage accruing from the use of benzoin is to fill up completely all the pores of the paper; air and moisture can no longer penetrate into the interior of the print, which is thus protected against the greatest, if not the only cause of deterioration. Besides this, benzoin communicates to paper the gloss of albumen, but in a less degree.

The chloridized paper will keep a long time; in order to sensitize it, place it in contact with the following bath

Water, 100 parts.
Nitrate of silver, 15 parts.

exactly as for albumen-paper.

If it be required to keep the sensitized paper for some time, it may be placed in one of Marion's* boxes, where it will keep perfectly.

The exposure beneath the negative is much shorter than for albumen-paper; the picture may be printed deeper than required at the end after fixing. If the time has been too long, the blacks become deep green, but there is no necessity for anxiety about the matter, the toning bath will restore them to their original black.

The prints may be toned either in the Bayard bath:

Water, 1000 parts.
Chloride of gold, 1 part.
Chloride of ammonium, 20 parts.
Hyposulphite of soda, 4 parts.

or in the acetate bath:

Water, 1000 parts.
Chloride of gold, 1 part.
Acetate of soda, 30 parts.

Glover's Resinized Printing Process.

Salting Solution.

Gum thus, 180 grains.
Gum mastic, 40 grains.
Chloride of zinc, 200 grains.
Alcohol, 8 fluid ounces.
Sulphuric ether, 2 ounces.

The object of adding the ether is to insure the speedy solution of the mastic. The paper is to be immersed in the above for five minutes, covering the dish with a sheet of glass to check evaporation. Take out, drain closely, and dry before the fire. Too much stress can not be laid upon the necessity of perfect dryness, so that if the salted paper be put away for future use, it must again be held some time before the fire, previous to floating on the silver bath, or it will not take tip the solution evenly. The silver bath is composed as follows

Alcohol, spec. grav., .805, 4 ounces. Dissolve.
Gum thus, 80 grains.
Gum mastic, 10 grains.
Nitrate of silver, 960 grains. Dissolve.
Distilled water, 4 ounces.

* This box is oblong or square, and constructed of zinc, with a tight-fitting cover. At the bottom there is a plate for containing fused chloride of calcium, above this a shelf of wire-gauze, on which the sensitized sheets are placed. When the lid is accurately closed, whatever moisture maybe in the box, it will be absorbed by the chloride, which is a very deliquescent salt.

Mix the two solutions; shake up well; filter, and add four drops of nitric acid. When the paper has been, in contact with the above solution a few seconds, it has a tendency to curl up, which must be checked by breathing upon the edges. After it has settled flat on the surface, allow it to remain ten seconds; it is then ready to be removed. Take hold of the sheet by one corner, and stroke it with a glass rod, kept for this purpose alone, to remove the surplus solution, and dry before the fire. It is then ready for fuming over a dish of ammonia. This last operation reduces the exposure in the printing frame about one third besides insuring success in toning, under almost every condition of the coloring bath.

On removal front the printing Items, wash in tepid water, and tone by any of the alkaline processes. That which answers best in my hands is composed of acetate of soda prepares at least twenty-four hours before use, with the addition of a few drops of the usual solution of chloride of gold immediately before immersing the prints.

Fix in a nearly saturated solution of hyposulphite of soda, containing five per cent of alcohol.

The subsequent thorough washing must not be neglected in this or any other printing process.

Or in any other bath.

The print soon assumes a black tone, which is difficult to obtain with albumen.

It is finally fixed in

Water 100 parts.
Hyposulphite of soda, 20 parts.

As soon as the print is well washed, it is left to dry, and afterward brushed over with a piece of flannel, or a pad of cotton, in order to give it a gloss. It is evident that varnishing is useless.


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