When the print has obtained full vigor, the developer is poured off, and, without any pre vious washing, the following clearing solution is flooded over it : * Acetic acid t drachm Alum. 8 ounces Water 32 ounces or this : Sulphuric acid i ounce Water too ounces Allow this to act upon the image for about a minute, then pour it away and apply a fresh portion. Then rinse and place in the fixing bath, made up with three ounces of sodium hyposulphite dis solved in 16 ounces of water, and tested for alkalinity.
After fixation, the prints are thoroughly washed in many changes of water for about two hours. They are then hung up and placed across a pole to dry.
The rough or mat surface papers appear to best advantage with most subjects if allowed to dry with their ordinary surface. A brilliant glossy surface may, however, be given to bro mide prints upon smooth paper in the following manner : After the prints are removed from the final washing water, they are squeegeed in contact with a sheet of plate glass, previously well cleaned and lightly rubbed over with French chalk (a powdered talc). Here they should remain until quite dry, when they are easily peeled off the glass with a surface equal to the glass itself. Instead of plate glass, a sheet of polished vulcan ite, celluloid, or even a ferrotype plate, may be used. With these, if properly cleaned, no special preparation is necessary. Bromide prints are mounted in the ordinary way. They appear to best advantage behind a cut out, or on a deep sunk mount.
If proper use of the clearing solution has been made, the pictures should be clear and free from yellow stains, the object being to remove these by preventing the precipitation of the iron from the developer in the paper. Over-printed proofs may be reduced by immersion in chlorine
water or in a solution of cupric chloride. If blisters appear in fixing, a little common salt should be added to the first washing water, or the prints placed in a three per cent. aqueous solution of chrome alum. The most scrupulous cleanliness must be observed with regard to the dishes used, and, in fact, with everything with which the paper comes into contact, as the faintest trace of hyposulphite of soda, pyro or free silver, will ruin the pictures entirely. The tray used for the oxalate development should not be used for any other purpose.
The tone of the prints upon bromide paper differs considerably with the different manufac tures of paper, and with the various methods of development. Agreeable tints may be obtained by the usual method of toning with chloride of gold. Bromide prints may also be toned with plati num by substituting it for the silver image. The prints should be very much over-printed and then soaked in the following bath until the desired tone is secured : Platinum perchloride 8 grains Distilled water. 3o ounces Hydrochloric acid ounce They are then washed and dried.
Bromide Negative Paper is a paper coated with an ordinary gelatine emulsion as used for dry plates, and described under Emulsion. Its treatment is the same as is required for ordinary dry plates. Owing to the opacity of the paper the printing process is much slower. Under Translucent will be found one or two methods of making the paper more transparent.