Those who point out that the formula for Pyrocat-HD has never contained pyrogallol are of course correct. I have made a few modifications over the years to the formula but the main reducer has always been pyrocatechin/pyrocatechol/catechol. Some of the accepted modifications I have myself used and/or described are the following.
Originally Posted by Leon
1. Substitution of metol for phenidone at the rate of about 10-20 parts metol to one part phenidone. This formula gives slightly better acutance with rotary processing, but slightly lower effective film speed.
2. Substitution of a 20% solution of sodium carbonate for the 75% solution of potassium carbonate. This requires changing the normal dilution from 1:1:100 to about 1:5:100, or 2:2:100 to 2:10:100. Some have also substituted sodium hydroxide for carbonate (see my article at Unblinkingeye. com) and this works fine also, though I think it gives slightly larger grain.
3. The addition of a very small amount of ascorbic acid (about 1ml of a 1% solution of ascorbic acid per liter of working solution). This bumps the energy of the developer up considerably without otherwise changing the characteristics of the developer. However, more than this kills the stain.
4. Changing the formula from sodium bisulfite to sodium metabisulfite since, as it turns out, most sodium metabisulfite is metabisulfite anyway.
5. The addition of EDTA (Trisodium variety) in amount of about 5 g per liter of stock solution as a chelating agent. Suggested only for those who mix their working solution with tap water of unknown quality.
6. Use of slightly more of Stock A than Stock B in the working solution when developing film for very long periods of time, as might be necessary for example when developing a low contrast film like JandC 400 exposed in a flat lighting situation. Instead of a 2:2:100 dilution I would now recommend a 3:2:100 or 5:3:100 dilution which will cut down slightly on B+F. I also recommend the asymmetrical solution for semi-stand and extreme minimal agitation where development times are very long. Say, instead of 1:1:150 use 1.5:1:150, or 3:2:300, or 5:3:300.
I have also experimented with the addition of more sulfite (you already get some from the sodium metabisulfite). The additional sulfite will make the formula much more energetic but kills the stain so I don't recommend this except for people who don't want the stain.
It is very true, as someone mentioned in a previous message, that changes in developer formulas almost always come at some cost, i.e. you can decrease grain but at the cost of acutance, or you can increase acutance at the expense of grain. Pyrocat-HD has a slight advantage in this regard because the grain masking that one gets with the stain it allows for much finer grain than if there were no stain. People are free to tinker with the Pyrocat-HD formula and use it as they will, and if that results in an improvement for their purpose, more power to them. I do a lot of tinkering myself, and indeed make modifications for specific purposes, but if I knew a way to significantly improve the formula in terms of its overall versatility, which is one of the truly great virtues of this developer, IMO, I would have already made that information available.
Last edited by sanking; 02-15-2005 at 09:08 PM. Click to view previous post history.