Home › Photography › Photography (To a saturated solution)

Photography (To a saturated solution)

To a saturated solution of the above salt in 6 oz. of distilled water add 220 grs. of nitrate of silver, previously dissolved in 1 oz. of distilled water, and intimately mix. This mixture, when crystala water-bath, is the salt used to sensitize the collodion. It may be kept in a bottle, but not necessarily in a dark place, because it is only sensitive to light when brought into contact with organic substances.

Dissolve 3 oz. of this salt in 10 oz. of alcohol, to which 5 drs. of distilled water and a few drops of nitric acid have been added. This is the sensitizing liquor, and does not require to be kept in the dark.

III. Preparation of the Resinized Collodion.

The collodion may be the ordinary plain preparation, containing about 51 grs. pyroxyline (not , containing about 54 grs. pyroxyline (not powdery) to the ounce of ether and alcohol, mixed in the proportion of 6 to 2; but, in order to give it an organic reaction with the sensitizing salt, it is necessary to add to each pint of the collodion about 10 drops of so-called "harz oel," which is thus prepared: Take equal parts of castor oil and Canada balsam; dissolve the latter in sufficient ether to enable it, when mixed with the castor oil, to pass through a filter. After filtration, evaporate the mixture over a water-bath till it is of the ordinary consistence of a fatty oil. The collodion is now ready for being sensitized.

IV. To Sensitize the Resinized Collodion.

To every 3 oz. of the collodion thus prepared add from 1 to 11 oz. of the sensitizing solution, from 1 to 1½ oz. of the sensitizing solution, with a few drops of nitric acid, and intimately mix. The collodion is now sensitive to light, and must be kept in the dark.

V. Sizing of the Paper.

This is an important preliminary to prevent the image from sinking into the body of the paper.

It is effected either by a tolerably strong solution of starch, Iceland or Irish moss, beaten up with about oneeighth its bulk of albumen and a few grains of acetate of lead. The paper may be floated on this in the usual way, and when dry is ready for the reception of the sensitive collodion.

VI. Applying the Collodion.

The paper is pinned down by 3 of its corners to a flat board, a little larger than the sheet to be collodionized. The collodion is poured on in the usual way , and the excess run off at the unpinned corner into the stock-bottle. This may be done with great deliberation, and more may be poured on to any part, where there is a deficiency, without much chance of its running in ridges, as would inevitably be the case if a glass plate were so treated. Hang up to dry in a dark room, and it is fit for the printing-frame.

VII. Preliminary Fixing.

When the picture is printed to the proper strength, that is to say, to the depth which it is wished finally to retain for uranic-developed pictures lose very slightly in the toning and fixing processplace it in a bath containing distilled water 40 oz., acetic acid 1 oz., and hydrochloric acid 1 oz., for the space of 10 minutes. The object of this bath is to remove the uranic salts insoluble in water . The prints are afterwards washed in several waters before being placed in the toning solution.

VIII. Toning the Pictures.

The ordinary alkaline gold-bath answers very satisfactorily, and tones uranic prints much more rapidly than similar prints on chlorized paper.

IX. Fixing the Proofs.

If the picture be toned in hyposulphite of soda and gold no further fixing will be necessary but if in the usual alkaline gold-bath, they will have solution, to remove the silver salts insoluble in to pass through a hyposulphite or sulphocyanide water . When thoroughly washed the process is complete.