Brain seizure: Pyrocat stock mixing

[RJ-]

I'm returning to the dihydrobenzene version of the Catechol developer from the raw substrate. In England it is available as the Part A pyrocatechol and part B Sodium Metaborate (Kodalk) raw material.

My notes from 2008 indicate that I was using a 1:5:100 ratio as Part A: Part B: Water. I've scribbled citric acid in but no idea why.

Returning to using this developer again, I can't remember at all how to make the solution of Part A or B up.

There are various internet suggestions for Sandy King's Pyro HD; Ansel Adams' version but none for the UK version which I can find.

I'm guessing, that Part A was constituted by 25gram Pyrocatechol; Part B as 25g, each in 100ml distilled water.

Can anyone who uses pyro confirm the stock mix ratios for the Part A & B?

It must be a really simple issue but it has been a long time since and I've no recollection.

Kind regards,

RJ

[Ken Lee]

See http://www.pyrocat-hd.com

[sanking]

See http://www.pyrocat-hd.com

Please note especially two articles on the Pyrocat website, one the general introduction I wrote about pyro type tanning and staining developers, http://unblinkingeye.com/Articles/PCat/pcat.html, and the other an article on mixing the various versions of Pyrocat, http://unblinkingeye.com/Articles/PCat/pcat.html.

Pyrocat was designed to work with a Part B solution of 75% potassium carbonate. It will also work with a 20% Part B solution of 20% sodium carbonate used at about 5X by volume the amount of potassium carbonate. Pyrocat will not work with sodium metaborate as Part B because the pH of a working solution would be too low. Some people have used sodium hydroxide in Part B, with good results, but I prefer the lower pH of the carbonates.

Sandy

[IanG]

I think your issue is you have an early version in your notes using Sodium Carbonate, Sandy changed that to Potassium Carbonate earlier than your notes .

The UK version is sold by Peter Hogan as Presyscol, which is or was Pyrocat HD withthe original Sodium Carbonate Part B, the only difference was Hogan claimed it was his own unique formula, The guy is a total fraud, he's selling a warm tone developer now based on something I wrote on APUG . . . . . . . .

Ian

[RJ-]

Thanks everyone.

it's none of these versions, although I'm thinking it might be easier to switch over to these ones. The staining production from this kind of Pyrocatechol was a dark brown; not the usual green tone.

The former UK Silverprint sold the Pyrocatechol type, before the Moersch Tannol type when Martin Reed owned Silverprint. My instructions were blurred in the sachet and Martin kindly clarified. The Sodium Metaborate was specific: definitely not Sodium Carbonate, since I have never been a high energy cocktail shaking developer, and Metaborate' buffering limits blistering. Sandy - the Sodium Hydroxide is the same recommendation from the older Bignan reference for film development which I used. There is something else in the former Silverprint Pyrocatechol which enabled this combination to work. I have the Bignan manual which i'll try and dig out.

I found this thread: http://www.largeformatphotography.in...p/t-34321.html

from 2008. It's incredible how much I've forgotten since then!

[RJ-]

Simpler staining Pyrocat

[sanking]

Simpler staining Pyrocat

RJ,

The developer you reference is not Pyrocat but a much earlier version of a pyrocatechin formula called the Windisch Pyrocatechin compensating developer, of which there were several variations. The most definitive version of the formula can be found on p. 116 of The Film Developing Cookbook, by Steven Anchell and Bill Troop, 1998. But the formula itself is much, much older.

Perhaps an earlier versions of the Windisch formula used metaborate as B solution, but I doubt it since the threshold of development of a Pyrocatechin is much too low for metaborate. The formula in the Film Developing Cookbook is based on sodium hydroxide.

Sandy

[RJ-]

Thanks Sandy -

I wasn't equating the Bignan's reference to Windisch' development with the Silverprint Pyrocatechol; merely clarifying that it is absolutely not Sodium Hydroxide alluded to above.

In your extensive pyro work, the same formula of Pyrocat HD on Mark Devine's website, seems to suppress the base fog over and above the Rollo-Pyro, or Hypercat variations. This looks closer to the Silverprint pyro than the other Pyrocat variations.

I've emailed Silverprint to ask if they have any archive on the datasheet for Pyrocatechol (also not on their safety datasheet appendix) combined with Sodium Metaborate.

While searching, I discovered another pyro resource which I had never noticed: https://www.flickr.com/groups/463756...7623749536111/
Jay de Fehr, who has also authored a few interesting pyro recipes also contributes.

Thanks for keeping your Pyro staining pages online. It's a great resource.

Kind regards,

RJ