Elon, Roylon, Metol and similar coal tar developing agents are derived from phenol (carbolic acid) which forms a large constituent of medium tar oil. But phenol itself and other phenol substances occurring in medium tar oil form also the raw material for the manufacture of explosives.
Enough said - Elon, Metol and similar developing agents are unobtainable in the open market at the present time. And there is little hope for the immediate future.
The logical thing to do then is to conserve any small reserve of such chemicals and consider seriously the use, in every way possible, of developing agents which are independent of this source of supply.
The two of these developing agents which offer the most satisfactory solution of the present problem are Pyrogallic Acid and Hydrochinon. In chemical composition the two are closely allied as Pyrogallic Acid is trihydroxy-benzine while Hydrochinon is dihydroxybenzine.
Pyro has been recognized for years as the standard developer for plates and films and we do not believe the printing quality of the pyro developed negative has ever been fully equaled by negatives developed by coal tar developers.
While many photographers have found it convenient to use the same chemicals for compounding developers for plates and papers, it will not be a hardship to go back to pyro, and if results are improved - so much the better.
Hydrochinon is being manufactured in the United States in increasing quantities and it is reasonably certain that the supply will keep pace with the demand. With the proper proportions of sodas and bromide, Hydrochinon makes an excellent developer for all developing-out papers, so the shortage of coal tar developers will not work any real hardship on photographers of this continent.
The following Hydrochinon developer has been found to be very satisfactory:
For Artura Iris :
C. K. Co. Sulphite of Soda 200 grains C. K. Co. Carbonate of Soda 3½ ozs. Dissolve chemicals in the order named.
Add one drop of a Saturated Solution of Bromide of Potassium to each ounce of the above developer.For Azo, Artura Carbon Black, Carbon Green Non-Curling and Chloride; also for Velox or Eastman Bromide Papers, used for commercial work or amateur finishing, the same developer.
EASTMAN PORTRAIT FILM NEGATIVE, ARTURA PRINT
From Eastman Professional School Demonstration may be used with the following exception:
Add one drop of a Saturated Solution of Bromide of Potassium to each 3 ounces of developer.
In using the above developer for Artura or Velox, the image shows more like an overtimed print at the beginning of development, but will clear and build up as development goes on.
Use at a temperature of 68 to 70 degrees.
[While the article below contains some suggestions that are not strictly applicable to Canadian conditions, it nevertheless offers valuable hints to photographers as to the lines along which profitable business mag be sought and developed. Commercial Photography is attracting more and more attention because of its varied possibilities, and the prudent photographer will steadily strive to make known the possibilities of his craft. The extract is from the British Journal of Photography. ]
Potassium Metabisulphite is a rather scarce article just now, but it has come to be looked upon by the photographer as almost a necessity. Its action as a preservative for Pyro in the developer for plates and as a preventive of blisters in the fixing bath for Bromide papers is such that a substitute which produces the same effect will be welcomed.
We are glad to state that the action of Sodium Bisulphite, which may readily be secured, is identical with that of Metabisulphite and may be substituted, part for part, in all our formulas specifying Metabisulphite of Potassium.You can secure Sodium Bisulphite from your dealer.