626. Saving Platinum Waste

Saving Platinum Waste. As considerable platinum remains in the print after developing, it is eliminated in the first acid water. By saving these acid baths one may reclaim a large amount of the platinum by adopting the following method:

627. Suspend in a 20 gallon jar four pounds of scrap zinc. Pour your first acid washing and all rejected developer into this jar. As the jar fills decant the clear water from time to time. Where much sepia paper is used, being in excess of the black paper, it may require the addition of a little muriatic acid to the solution to make it sufficiently acid to clear the bath from yellow to white. When the zinc is entirely eaten away, to reclaim all of the platinum, new zinc must be added. As long as zinc remains in this jar it will continue to throw down all added platinum. About once a year the sediment should be gathered, packed and sent to the refiner.

628. Warmer Sepia Produced By Toning With Nitrate Of Uranium

Warmer Sepia Produced By Toning With Nitrate Of Uranium. Sepia tones, even to a dark red, can be made on any black platinum paper by treating it after development in a special sepia toning bath. Print to the same depth as for black tones; develop and clear them thoroughly and wash in the usual way.

629. Preparing Uranium Sepia Toning Bath.

Water........................................

.12 ozs.

Nitrate of Uranium...............................................

.60 grs.

Ferricyanide of Potassium (Red Prussiate of Potash)....................................

.42 grs.

Sulphite of Soda Crystals.........................

.18 grs.

Acetic Acid.................................

6 drops

630. Place this in a bottle labeled "Uranium Sepia Toning Bath." The more acid used in the bath the warmer will be the resulting tone.

631. Toning

Toning. The prints having been previously developed, cleared and washed are ready for toning. Place them into the toning bath one at a time, allowing them to remain until the desired color has been produced. This bath should be used at a normal temperature - about 60° to 70° Fahr. The first change will be to a purple-brown, the next stage brown, and then by prolonged toning they will run into red. Prints should be handled over and over during toning, to produce even tones. After the prints are thoroughly toned, wash by hand for 15 minutes, drying in the usual manner.

632. Caution

Caution. The tray used for this toning bath must be used for no other purpose and must be kept perfectly clean. The above toning bath is not recommended for permanency or evenness, but for the extremely odd and striking color effects which may be produced through its use.