View Full Version : Basic Intro/Info for Pyrocat HD?

23-Jun-2015, 08:25
Well there seems to be tons of resources on Pyrocat-HD. Even a website, perhaps by Sandy himself?

I did find this thread (http://www.largeformatphotography.info/forum/showthread.php?122209-Pyrocat-HD-source&highlight=pyrocat) to answer my first question...where to buy.

Although other than seeing it commonly used and praised, can someone give me a quick few points about it? Before I dive in and think about utilizing it, and researching I am clueless about it.

I see things such as: oxidation, brown tones instead of green, good for VC paper (IDK what that even is, I know of RC and FB...I generally only print on FB), A and B solution, etc. I believe I will go with liquid already mixed from photoformulary to start. But why is it popular?

I currently use (always have unless pushing film) Kodak D76. For 35mm, 120, and now 4x5. To be honest, I develop film about once every 2 months. I often dump 500-1500mL of D76 since I keep it dated for 6 months in glass bottles.

1) Shelf life? Does it last a long time mixed or something?
2) Dilution? People use it because it is like 1:100 or something?
3) Advantages?
4) Praised because it is affordable/grain/sharpness/shelf life/longevity/etc?

Any basic information will help me. I clicked on about 5 different threads, but generally very specific questions on particular film/case studies/glycol/etc etc. I just want to determine if I should consider trying it out. Thanks in advance for help.

PS: If considering switching after finding out a bit about it...I will read this (http://unblinkingeye.com/Articles/PCat/pcat.html) first. Written by Sandy King.

Rick A
23-Jun-2015, 09:11
For starters, Sandy is a himself.
Pcat-HD mixed in water has a short shelf life, mixed with glycol lasts a very, very long time. Once mixed to working dilution, has a short useful time span, in other words, mix, use immediately, dump.
Usual mix is 1+1+100
The rest is subjective based on personal preferences. It is somewhat economical, a little goes a long way.

Michael R
23-Jun-2015, 09:28
I suggest reading Sandy's article first. Actually it might help to take a step backward before getting into this if you don't know what VC variable contrast paper is. Some basic info on developer types etc. is a good place to start.

Basically, Pyrocat HD is a staining/tanning developer. With this type of developer, the optical densities of the negative come not only from silver, but from dye (a development reaction product) formed in proportion to the amount of silver. This means you need less silver for any given negative density, which can help improve acutance. In addition, this type of developer is part of a broader class of relatively dilute, non-solvent developers, and those characteristics also tend to contribute to increased acutance, with more pronounced edge effects, both of which will contribute to an overall increase in the subjective sense of "sharpness". While this comes at the expense of increased graininess relative to fine grain developers, the lower silver densities associated with a staining developer help offset some of the increase in graininess normally associated with acutance developers.

Of the various staining/tanning developers, Pyrocat HD has a reputation for being somewhat less finicky and more flexible (ie not only easier to use, but also more accommodating of different processing procedures with respect to agitation etc. and more adaptable to alternative printing processes). It will also tend to give you better film speed than most staining developers. There are reasons for all of this which I won't get into here.

A pre-mixed liquid concentrate is probably a good idea to start. Also make sure to read the safety instructions - one of the primary active compounds in Pyrocat HD is catechol, a relatively nasty chemical.

Hope this helps.

23-Jun-2015, 09:49
Thanks for the advice, both Rick and Michael.
And my apologies to Sandy!

That does help and answers my questions. I will dig into it a bit more.

In relation to what Michael said, that makes sense. I assume a reason why people use with LF as well due to grain size, generally, not being too much of a concern. And duh, I know VC...just wasn't thinking. Allows you to control contrast by adjusting the level of magenta the enlarger throws out via filters.
Interesting as I always thought negatives developed via the silver content alone being converted and thus using fixer to remove any remaining silver content. I was unaware you could even stain or tan to develop a negative. Ah...so much to learn.

It seems another advantage is it lasts a very long time. So you just suck out 10mL+10mL (if using 1L container) and mix before using. This allows the stock solution to stay around in supply as you only use when developing then dump. This would be an advantage for me.

Anyway, I won't bog down the thread with repeated content and technical details. I appreciate the information and heads up about using Pyrocat HD. I did read about the nasty chemicals involved and to use proper gloves/ventilation, especially when mixing yourself.

David Karp
23-Jun-2015, 09:57

13-Jul-2015, 16:24
Hello, I am a complete newbie to LF, and to this forum... trying to teach an ol dog so to say. I am supposed to be getting my Chamonix 4x5 "in August".. what ever.. I'm trying to cram my brain as much as I can before it gets here...
I'm researching developing methods and chemicals ... I think I will prob go with the BTZS tubes... the PMK-Pyro sounds interesting.. but not sure if I should start with that, or if it can be used successfully with the tubes...
Do you have and suggestions or tips you care to pass along.. no local darkrooms or even labs that still process- "we ship it off"... thanks, Ann

Steve Sherman
13-Jul-2015, 16:44
There're several readily available Pyro based developer formulas, one using Pyrogallol as the root Pyro the other using Catechol as the Pyro component (Pyrocat family) While my choice would always be the Pyrocat family it does take on a bit more importance if the Silver Gelatin process is in your future.

Clearly you have made a wise choice in the decision to start with a Pyro based developer, they are far superior for many reasons which need not be rehashed at nauseam