A New Generation Of Staining Developers
by Jay De Fehr
Pat Gainer's innovative work with organic solvents for developer stock solutions has opened the door to a new generation of staining developers that have overcome many of the problems traditionally associated with this class of developers. The shelf lives of concentrated stock solutions in either TEA (triethanolamine) or propylene glycol, measure in decades, because they do not oxidize like aqueous solutions do. This fact provides opportunities for unique formulations.
Photographic developers traditionally share five common components:
- The preservative
- The reductant, or developing agent
- An alkali or activator
- A restrainer
- And a solvent
Integration:
The typical preservative for photographic developers is sodium sulfite, which can degrade sharpness by its solvent action on silver grains. The use of an organic solvent makes a traditional preservative unnecessary. If TEA is used as the solvent, it also performs the role of the alkali in the working solution, performing three of the five vital roles in a developer, leaving only the developing agent/s, and the restrainer, but a well balanced developer does not require a restrainer. By exploiting the principle of integration, it is possible to formulate a practical developer containing only TEA, and a single developing agent, such as Pat Gainer's Pyro-TEA. Pat's excellent developer, PC-TEA uses the ascorbic acid/phenidone pair in TEA.
Staining developers:
Staining developers offer some important benefits, and present some important problems, both of which are well documented, and won't be treated in depth here. Staining developers have long been prized for their unique tonality, and acutance, and by UV process printers, for the increased contrast and density range made possible by the proportional image stain. Pyro developers were among the very first, but didn't make the transition to rollfilm and miniature formats, due to their inherent graininess, dubious keeping properties, unpredictability, and toxicity, and were replaced for the vast majority of photographers by MQ developers.
Stain formation:
Pyrogallol, catechol, and hydroquinone will produce a proportional image stain in the absence of sulfite, but since sulfite is also the most practical preservative, staining developers were typically made up in three separate stock solutions; one with the developing agent, another with the sulfite, and a third with the alkali. These three stock solutions had very disparate keeping properties, which made the performance of the developer unpredictable from one working solution to the next. As the sulfite deteriorated, the stain became less proportional, with an increase in general stain, which acts like fog. The proportion of sulfite to pyrogallol or catechol is critical in controlling stain formation, but very difficult to maintain in an aqueous solution. Organic solvents provide a convenient solution to the problem of preservation of the stock solution, but what about general stain? If the working solution contains no sulfite, the developer oxidizes very rapidly, and stains less selectively, resulting in high general stain. Can we add sulfite to the organic solvent? Yes and no. Sodium sulfite is not readily soluble in organic solvents. A small amount can be dissolved given a high enough temperature, and enough stirring, but temps far above the boiling point of water can be very dangerous, and are best avoided, if possible. Fortunately, there is an excellent alternative that offers advantages over sodium sulfite, beyond solubility. Ascorbic acid works in much the same way as sodium sulfite to prevent oxidation of the developing agent and control stain formation, is readily soluble in organic solvents, and is itself a developing agent.
Stain and printing:
Stained negatives print differently on VC papers than they do on graded papers, due to the spectral sensitivities of the papers, and the color of the stained negative. VC papers are sensitive to both blue and green, which is the basis for their contrast control. The color of a stained negative essentially acts like a low contrast filter with VC papers, so a negative that prints well on grade two paper, will require a grade four or five contrast filter to print similarly on VC paper, or conversely, a stained negative that prints well on VC paper with a grade two filter, will require a grade 0-00 graded paper to print similarly. This principle can be exploited in the development of 35mm films to produce extremely sharp and very fine grained negatives.
Two developers, two solvents:
Pyrogallol is a very active developing agent at a pH of around 10, which makes it an ideal candidate for a TEA-based developer. TEA-based developers are single-solution developers that are simply diluted with water to make a working solution, and represent the ultimate in simplicity and convenience. Catechol requires a higher pH than TEA can provide, to work effectively, so catechol is better suited to glycol-based, two-solution developers. The first solution is a glycol-based concentrate containing the developing agents, and the second is a simple alkali in an aqueous solution. The two solutions are added to water to make a working solution.
Mixing:
Since neither 510-Pyro nor Hypercat contain sulfites or bromides, all of the chemicals will dissolve at about 150F. Just add the dry chemicals to the TEA or glycol at room temp, heat in microwave, conventional oven, or on stovetop, with continuous stirring, until all of the chemicals have dissolved, then top up to final volume.
510-PYRO
| TEA | 75 ml |
| Ascorbic acid | 5 g |
| Pyrogallol | 10 g |
| Phenidone | 0.25 g |
| TEA to make | 100 ml |
Mixing instructions: Add chemicals in specified sequence.
Dilution: 1+100
Starting point development time: 5-7 mins.
Notes: Can also be diluted up to 1:500 for EDRA (extended development/reduced agitation) techniques, with one minute initial agitation, followed by one inversion every 10-15 minutes for one hour, or so.
HYPERCAT
| Stock Solution A | |
| Propylene glycol | 75 ml |
| Ascorbic acid | 0.5 g |
| Catechol | 10 g |
| Propylene glycol to make | 100 ml |
| Stock Solution B | |
| Distilled water | 750 ml |
| Sodium Carbonate | 200 g |
| Distilled water to make | 1 L |
Mixing instructions: Add chemicals in specified sequence.
Dilution: 1+10+100
Starting point development time: 5-7 mins.
Notes: Dilute up to 1+20+500 for longer development times, and increased edge effects
510-Pyro and Hypercat are highly concentrated acutance developers, designed specifically for use with their respective solvents. Both developers produce very fine grain, and full film speed, are suitable for all films and formats, and all development methods, including rotary processing. Any practical development time can be used by adjusting the developer dilution. Both developers are very clean working, producing very low fog, even when developing to the high density ranges required for UV processes. TEA and glycol concentrates are easily and accurately measured and dispensed with a measuring syringe.3ml, 6ml, and 25ml syringes cover a very wide range of dilutions and working solutions. Since these developers are so concentrated, small variations in dilution make no practical difference in the performance of the working solution, so it is perfectly acceptable to simply add the required volume of concentrate to the total volume of water. In other words, if one wishes to make up one liter of a 1:100 dilution of 510-Pyro, one can simply add 10ml of concentrate to 1 liter of water.