Lowell Huff wrote:Almost all powder formulas are pre 1920 in origin. As powders they are are not as sophisticated as modern liquid formulas. In pre 1920, Scientists did not have the advantage of all the research into photography that was done in the following sixty years. The pre 1920 formulas were designed for those same emulsions. How many of those emulsions remain today? While those formulas will develop today's emulsions, their lack of sophistication will not "OPTIMIZE" the capability of todays' films and papers. The discussion on their economy of shipping and storage issues does not belong in a discussion of image quality; but i can address it if you wish, in a later "Fataw".
Microphen, uses Phenidone A instead of Metol as the "superadditive", which, in my estimation, makes it an improvement over the older powder formulas. It does not contain any anti fogs or anti cals.
XTOL's claim to fame is that it does not contain HQ as the developing agent. So what? It is a low to medium contrast film developer with all the inherent, well documented problems of mixing two different bags of powder into a liquid. Without HQ it is less likely to oxidize during periods of non use. It can be replenished and can be used as manual or in a machine processor. It is clearly superior to the other developers in this discussion.
If you would like me to compare these chemicals to Clayton's, I can do that. If you did not know, Ilford chemicals are manufactured by Tetnal and Kodak chemicals are manufactured by Champion Chemical.
CLAYTON CHEMICALS are made by CLAYTON CHEMICAL.
That's not quite accurate. Many of the powder developers are much newer than that. D-76 dates from 1927, and I think DK-50 and DK-60a date from the mid-30s (when Kodalk was introduced, I believe), but the much newer developers such as Acufine, Ethol UFG, Microphen, and other PQ formulas are not radically different from those developers. A developer is really not that complicated. You need a preservative (usually), developing agent (always), a restrainer (sometimes) and an accelerator (usually). Amidol does not require an accelerator or preservative, because it is so chemically active, and dies quickly no matter what you do.
The main driving force for modification of developers is the need to achieve better results with 35mm film. This is what D-76 achieved, as the first really mild, fine-grain developer that gave full film speed. Most developers before then had been too aggressive for miniature work, and even after D-76 was introduced, many attempts were made to produce even finer grain using solvent-type developing agents such as paraphenylenediamine. These reduced speed significantly. Kodak developed a formula called DK-20 which used small amounts of sodium thiocyanate (similar to fixer) as a solvent, to try to reduce graininess. It was discarded decades ago, as it produces dichroic fog with modern emulsions.
The production of faster and finer-grained films was the answer, and today's films are vastly superior to what was available in 1927.
Because D-76 is so widely used, Kodak and other companies make their film work well with it.
http://en.wikipedia.org/wiki/Photograph ... er#Formula
http://www.archive.org/stream/journalof ... h_djvu.txt