I use both 35mm and 4x5. I shoot mostly B/W processing my own using D76. I've been interested in trying other developers and have seen frequent references to Pyrocat. Can anyone explain it's virtues or pros and cons for me. Oh, I've generally been using T-Max film if it matters. Any input would be appreciated.
Catechol (aka pyrocat) and Pyrogallol are developers which will not only form image silver, but also form a brown stain wherever silver was developed. This gives some degree of image amplification or less grain for same density. Historically Pyrogallol was prefered, but since it is very toxic people moved to Catechol.
There are many resources dedicated to pyrocat developers which list mixing and developing instructions together with properties of their concoctions.
Pyrocat is preferred by many current workers over pyrogagallol (pyrogallic acid) for several reasons.
1. somewhat less toxic although gloves should be worn with both.
2. The stain is less intense, but a part of the spectrum which provides for more contrast in the print.
3. The stain masks the grain of the film.
4. the printing time is usually shorter than for pyrogallol negatives.
5. Both forms of pyro tan the emulsion providing more protection from scratches.
6. Separation in the highlights is superb when compared to MQ or PQ developers
7. It is probably the cheapest developer around when diluted to working dilutions.
8. if mixed in polyethylene glycol, which it should be, it lasts for an extreme length of time. I have never had any go bad.
9. the scale of the negative is enhanced because the film curves don't have unusual fluctations.
10. since the concentrates are liquids, it is quick to get ready for use.
I can go on, but this should be enough. By the way,I have spent considerable time over the past 70 years working with various develoers and currently still maintain solutions of four different pyro develpers. Pyrocat HD+ is my absolute favorite.
Do you mean Propylene glycol?
First ask yourself what sort of direction you want to move in vs stock D-76. Asked another way, what specifically don't you like about it, or what specifically you are looking for. That will help a lot, because much of what is written about staining developers is more myth than anything else. For example, "highlight separations" are frequently talked about. I found no advantage over a moderately diluted solvent developer like D-76, nor does rational sensitometry support this notion. Another strange argument concerns "grain masking". For one thing the formulators are careful to point out this effect (combined with lower silver densities) can lead to finer grain in comparison to non-staining high definition developers, not in comparison to solvent developers. The other interesting thing about grain masking is it requires the spreading of dye. This would appear to contradict the purported effects of tanning and reduced "migration" (questionable) on acutance.
Much of my photography is dones under extreme subject contrast conditions. I worked a lot with PMK and WD2D+ Pyro formulas. They are fine developers, but not magical. The Pyrocat formulas developed by Sandy King use Catechol. The most common version is the Phenidone-Catechol Pyrocat HD. I have never used it but it has a fine reputation. It also appears to be more flexible than the above mentioned Pyro formulas in that people use it with rotary processing, reduced agitation techniques and some even use it as a two bath.
Just remember, you don't get something for nothing. You can't have both high acutance and fine grain, and you can't have both highlight compensation and enhanced highlight separation. There is no "free lunch".
Michael, excellent question. I can't say I dislike anything about D76. Probably more curiosity. Good food for thought. Thank you for your candor.
Originally Posted by Michael R 1974
I don't want to discourage you from trying these things, of course. Just have a healthy skepticism. In the end, trying for yourself is often the best way to figure things out when it comes to this stuff, because there is very little in the way of objective data out there. Just work with it yourself and decide if you like it. Pyrocat is probably a good one to try because it seems it is more forgiving and flexible than some other staining developers. Something to keep in mind: Don't try to evaluate stained negatives by eye, because you're really only seeing the silver density, not the additional stain density the paper will "see". Even densitometry is less than straight forward. So make prints. A stained negative that looks too thin and low in contrast might print just right.
Agree 100% with what Jim says, I've tried a lot of developers over the last 50 years and it's the best alround developer I've found, consistenly excellent results and negatives that are remarkably easy to print.
Originally Posted by Jim Noel
This is the first of my images from negatives that I processed using Divided Pyrocat HD which is supposed to give a compensating effect to high contrast situations, although I normally use Pyrocat HD in its mixed form I thought I would try the divided Pyrocat HD as I wanted to get some detail from the semi-circle window. I am very pleased with the compensating effect, I could not believe the amount of detail from the semi-circular windows bearing in mind how high the contrast between the light outside and the very dark conditions inside.
The measured exposure was 30 secs @ f45 at ISO25, although the exposure I actually gave was 4 minutes at f45 on Adox CHS25 which will give an idea of how dark it was although I did allow 1 stop for reciprocity and I also had the Centre Filter on the 72mm Super Angulon XL which ate up another 2 stops.
Redundant Pressure Filters (Tottiford Water Treatment Works) by Ed Bray, on Flickr
You see all these claims as to how poisonous it is, but at one time it was used as a hair dye (pyrogallol). The same article I read also says metol and hydroquinone are poisonous. I wonder if pyro is really all that dangerous, or is it dangerous by today's standards, where EVERYTHING is poisonous. I'm thinking of switching to it after everything I've read on this site.