Most properly formulated paper developers will give prints without fog or stain at 68 to 70F with reasonable fresh paper and with the use of print tongs for handling paper in the developer. However, gray or brown chemical fog will often appear along the edges of prints when developer temperature runs 75 or over, or when prints are warmed in spots by contact with the operator's hands while saturated with developer. This tendency becomes greater with certain developers as more and more prints are pushed through the solution, leaving dissolved silver salts and developer oxidation products.
Adding Edwal Liquid Orthazite directly to the developer will restrain the aforementioned types of fog, allowing the developer to be safely used at higher temperatures and for a larger number of prints. The amount of Orthazite needed differs from developer to developer and should be determined by experimentation, taking the minimum quantities that are suggested on the bottle label as a starting point. Just enough Orthazite should be added to cut out the fog or edge stain. If too large a quantity of Orthazite is used, it will hold back development sufficiently to require extra exposure and in some cases to give a warm-toned image.
Old photo printing paper has more tendency to give chemical fog and edge stains than new material. Addition of just enough Orthazite to prevent the fog will usually enable out- dated papers to produce good prints. The recommended procedure is to start with the minimum quantity of Orthazite given on the bottle label and add more only if the fog or stains persist.
Some enlarging papers in combination with certain developers tend to produce a greenish tone print instead of the cold tone desired. A more bluish black image can be obtained just by adding Orthazite direct to the developer. Follow the recommendation on the back of the bottle and experiment with various dilutions. If you mix your own formula, reduce the potassium bromide to 1/10th or 1/6th the usual amount and just enough Liquid Orthazite to prevent developer stain or fog. Some very rich black tones can be obtained with almost any cool-tone papers using this procedure.
Addition of a very small amount of Liquid Orthazite to D-76 and similar developers will cause some improvement in graininess, though there will be some loss of film speed. 2 cc. of Liquid Orthazite added per gallon of Borax developer causes a slight improvement of graininess with no apparent change in film speed. Addition of an extra 4 cc. of Liquid Orthazite (total 8 cc.) per gallon will result in a speed loss of 2 f-stops but also grain improvement. Further addition of Orthazite causes more speed but no particular grain improvement.
Edwal Liquid Orthazite is a ready-to-use anti-fog preparation containing benzotriazole.