Temperature of developer, about 1700 Fah. This developer is complete in itself and requires no addition.
For those who are unable to obtain the sepia developing salts, the following developer is recommended : Ordinary oxalate developer, normal strength (1 lb. oxalate dissolved in 54 oz. of water) .............. 10 parts.
Saturated solution of oxalic acid . . . . 1 part.
The solution must be heated to a temperature of 160o to 170o Fah. to obtain the greatest amount of brilliance and the warmest colour, but very good results can be obtained by using a cool developer.
The development is effected by floating the printed surface of the paper for five or six seconds upon the "developing solution." To avoid air bubbles : lay one edge of the print upon the solution near the right-hand end of the dish ; then, with a sliding motion towards the left, lower the print, with an even movement, without stoppage, until it is entirely in contact with the liquid, where it must remain until complete action has taken place.
The solution is conveniently contained in a flat-bottomed dish of enamelled iron, heated by a small Fletcher gas stove. If no gas is obtainable, a spirit-lamp may be used for the smallest dish, or for the larger dishes a paraffin-stove.
Granitine dishes may also be used, and if ordinary care is taken will stand the heat without cracking.
It is advisable to put a thin piece of tin between the flame and the dish, to spread the heat.
As, owing to the temperature of the bath, evaporation takes place, it is necessary to add, from time to time, sufficient water to bring the bath nearly up to its original bulk. The developer obviously cannot be kept fully up to bulk by this means, as each print uses up a certain amount. Fresh solution must be added from time to time to make good such waste.
Greater care must be used with sepia than with black paper to avoid exposure to light, both when examining the prints and even in the first acid bath, otherwise the whites will be discoloured.
Discoloration of the whites is due to one of the following causes : 1. Too much exposure of the developing solution to light ; 2. Use of an iron dish in which the enamel is cracked so as to expose the iron ; 3. Paper kept too long ; 4. Exposure of prints to too much light while clearing.
The developing bath after use must be kept in the dark. This bath must not be used for " black " prints.
The prints are cleared in an acid bath of 1 part hydrochloric acid (s.g. 1.16) to 60 parts of water.
As the " Sepia " prints, unlike the " black " ones, may be affected by light when in the acid bath, the lights being stained and degraded, the prints at this stage must be manipulated in a very weak light. The prints are damaged by being left long in the acid baths.
The subsequent operations are the same as for the other kind of paper.
Granitine baths or dishes, carefully heated, are the best to use for a sepia developer.
An enamelled iron dish which has been once used in developing sepia prints, should on no account be afterwards used in developing black-toned prints, or the purity of the blacks will be destroyed.
Black and sepia prints should never be cleared or washed together in the same dish, for the reason given in the preceding paragraph, nor should black and sepia papers be stored together.
THE " JAPINE " PLATINOTYPE PAPERS. These papers are made in two grades, black and sepia.
The " Black Japine " is developed in exactly the samel way as the other black platinotype papers, with the exception that the floating on the developer may be prolonged for one or two minutes, development being much slower.
For the " Sepia Japine " the development is as follows : DEVELOPMENT. The special " Sepia Japine " developer is recommended, as undoubtedly giving the best results.
Dissolve the whole contents of the tube of special " Japine ' developing salts in 32 ozs. of hot water (rain or distilled). When the salts are dissolved allow the solution to cool, then add 10 ozs. pure glycerine (which must be free from acid). The whole must be thoroughly mixed and strained through muslin.
The developing solution must not be exposed to strong daylight ; if this precaution is taken it will keep indefinitely. Use plenty of developer to avoid scraping prints on bottom of dish.
This developer is used without dilution, at a temperature of 100° to 120o Fah., or it may be used cool. In most cases the results obtained by the higher temperature will probably be preferred. The cold developer should not be allowed to drop below 8o° Fah.
The exposed prints are wholly immersed in the developer. From two to four minutes should be allowed for full development, according to temperature. Several prints may be developed together, gently turning them over a few times to ensure equal action. The developer may also be applied with a brush.
N.B. - Full development is essential in order to obtain the richest tones.
Atlernative Formula. - Platinotype sepia salts - 1/2 lb. packet dissolved in 32 ozs. of hot distilled or rain water. Working temperature 160o Fahr. This developer gives rather warmer tones than the special " Japine " developer, with less depth of colour in the shadows. The use of enamelled iron dishes is not recommended. Granitine dishes can be employed with safety.
The print, after removal from the developer, is immediately placed in Pure hydrochloric acid ........ 1 part.
Water .............. 60 parts.
Three baths are necessary, the times of immersion being respectively five, ten and fifteen minutes. The prints should not communicate to the last acid bath the slightest tinge of colour. If this does not remain as colourless as water, when a depth of at least two inches is viewed in full daylight, the prints should be treated to yet another acid bath. Pure acid must be used.
Four or five changes of water for about twenty minutes will be sufficient.
After washing, immerse prints for about ten minutes in Glycerine .............. 1 part.
Water .............. 20 parts.
This solution can be used repeatedly.
DRYING AND MOUNTING.
The prints are conveniently dried between clean blotting paper, without pressure.
Any good tenacious mountant may be employed in the usual way, but the recently introduced dry-mounting method will be found the most satisfactory.
IVORY BLACK PLATINOTYPE.
The instructions for this new paper, which is made in two grades, smooth and rough, and which gives a brown-black image on a toned ground, is the same as for the Sepia papers save, that the Sepia salts are diluted with 80 ounces of water and the temperature should be 120o F. The results are almost like a photogravure.
THE GORGE OF THE ZAMBESI. Taken with the Sinclair "Una" Camera.
E. G. Becher, Esq.