Pyrogallol vs Pyrocatechol Stain Over Time

Shawn Dougherty · Apr 11, 2015

How much should one expect stain to change over time? Is there a difference in longevity between Pyrogallol and Pyrocatechol stain?

I got to hold a surviving Brett Weston 8x10 negative last year (Anso Saftey Film) and it still had a heavy brownish stain...

swmcl asked the following question in the 'Image Stain and General Stain' thread but I thought it deserved it's own.

swmcl said:
The stain on my sheet that came out green previously seems to have changed a bit toward a brown and the stain may have faded. All a bit subjective if I don't measure it I guess. But .. here's a question ... do the different stains (pyrogallol vs pyrocatechol) change over time and how sensitive are they to UV or IR ? I did read they were sensitive so I'm not asking if they are but more how much they are sensitive ...

Cheers,

Thank you.
Shawn

Gerald C Koch · Apr 11, 2015

The brown stain formed with pyrogallol consists of humic acids which are insoluble in water and should be quit stable. Other colors should be considered like the dyes in color film and they are subject to fading should the negative be exposed to light for long periods.

Shawn Dougherty · Apr 11, 2015

Thanks, Gerald.

Michael R 1974 said:
The question I ask in the other thread, however, is - how would you know?

That's true. I've heard a photographer state that a certain negative was getting harder to print because the stain was starting to fade. Unless it's so obvious as to be visibly distinguishable I also wonder how one would know. It seems other known variables over time would be more likely culprits of changes in printmaking, unless the negative was stored under poor conditions.

MattKing · Apr 11, 2015

If one had a pyro negative with an apparently faded stain could it be revived by a further dip in developer?

A sort of "pyro negative spa treatment"?

Gerald C Koch · Apr 11, 2015

MattKing said:
If one had a pyro negative with an apparently faded stain could it be revived by a further dip in developer?

A sort of "pyro negative spa treatment"?

Using a rehalogenating bleach and redeveloping should work.

Gerald C Koch · Apr 11, 2015

I should qualify my previous post in that any fading must be uniform across the negative. That there was no uneven illumination on it during the fading. Of course the best thing is to avoid any fading in the first place.

Doremus Scudder · Apr 13, 2015

Gerald and Michael,

Maybe you can comment on the neutralization/removal of the pyrogallol stain that occurs when using a sodium sulfite-based wash aid, or when treating the negative in Kodak Rapid Selenium Toner. This latter I used to use for intensification of the odd negative from time to time. When I tried to locally intensify a PMK neg, the selenium toner (1+2) nicely removed all the stain, rendering the technique for pyro negs unusable. A pyro neg treated for five minutes in selenium toner loses all its stain; the intensification from the selenium just about makes up for the loss of stain.

Any ideas what the mechanism is here?

Best,

Doremus

Gerald C Koch · Apr 13, 2015

A reducing agent such as sulfite can bleach a stain images.

Selenium toning should not be used for intensifying a stain negative. The selenium toner works on the silver images and cannot intensify the stain image. The only way to intensify a stain image is to use a rehalogenating bleach and redevelop with a stain developer.

c6h6o3 · Apr 14, 2015

Shawn Dougherty said:
How much should one expect stain to change over time? Is there a difference in longevity between Pyrogallol and Pyrocatechol stain?

I got to hold a surviving Brett Weston 8x10 negative last year (Anso Saftey Film) and it still had a heavy brownish stain...

swmcl asked the following question in the 'Image Stain and General Stain' thread but I thought it deserved it's own.

Thank you.
Shawn

I have negatives developed in ABC pyro about 15 years ago which have lost nearly all of their stain. They've been stored in plastic negative sleeves in a loose leaf binder kept in a drawer. I'm wondering if there was some interaction between the plastic and the negatives.

One of these negatives was very thin. It was so thin that the correct exposure when printing it on Azo Grade 3 was 3 seconds. The print, however, was absolutely gorgeous. Glowed like radium. The only thing that made it printable at all was the very noticeable green stain. Now there's so little stain that the thing is unprintable. This is how I know that it's not my imagination.

I've only been using Pyrocat about 10 years, but all my negatives developed in it still have a very strong brown stain.

Photo Engineer · Apr 14, 2015

All dyes fade with time. Only color film and paper have had R&D expended to extend their lives, but the rest are chancy. Staining developers have been one of my main points of "attack". Nothing is really known about their keeping qualities.

PE

mrred · Apr 15, 2015

So far then, bleach-redevelop is the only known treatment?

Photo Engineer · Apr 15, 2015

AFAIK, yes. And IDK the true keeping qualities of the stain, nor the quality of the redeveloped image. Redevelopment may cause more hardening with an increase in relief image if that is part of the original developer's properties.

PE

DREW WILEY · Apr 15, 2015

I've been routinely developing numerous kinds of film in pyrogallol for about 25 years now and haven't noticed any loss of stain in even my earliest negs. That might not be much of a track record in the overall scheme of things, but at least in terms of being able to predict printing
quality in my own remaining career it certainly is.

Shawn Dougherty · Apr 15, 2015

c6h6o3 said:
I have negatives developed in ABC pyro about 15 years ago which have lost nearly all of their stain. They've been stored in plastic negative sleeves in a loose leaf binder kept in a drawer. I'm wondering if there was some interaction between the plastic and the negatives.

One of these negatives was very thin. It was so thin that the correct exposure when printing it on Azo Grade 3 was 3 seconds. The print, however, was absolutely gorgeous. Glowed like radium. The only thing that made it printable at all was the very noticeable green stain. Now there's so little stain that the thing is unprintable. This is how I know that it's not my imagination.

I've only been using Pyrocat about 10 years, but all my negatives developed in it still have a very strong brown stain.

Thanks, Jim. I remembered you mentioning this somewhere along the line... It made me nervous. The only staining developer I use is Pyrocat HD so it makes me feel better to hear that your negatives developed in it are still looking good.

DREW WILEY said:
I've been routinely developing numerous kinds of film in pyrogallol for about 25 years now and haven't noticed any loss of stain in even my earliest negs. That might not be much of a track record in the overall scheme of things, but at least in terms of being able to predict printing
quality in my own remaining career it certainly is.

That's reassuring. As long as my negatives last as long as I do I'm happy.

dpurdy · Apr 15, 2015

I have been leery of the stain fading for sometime so I never leave them on a lit light table and certainly not in any sunshine. Better safe than sorry.

Shawn Dougherty · Apr 15, 2015

Photo Engineer said:
All dyes fade with time. Only color film and paper have had R&D expended to extend their lives, but the rest are chancy. Staining developers have been one of my main points of "attack". Nothing is really known about their keeping qualities.

PE

That's interesting, Ron. Anecdotal information is all we have then. From what I've heard MOST peoples stained negatives have held up long enough to be printed by them throughout their lifetime, which is all I'm after...

Photo Engineer · Apr 15, 2015

There is really no quantitative or scientific data on keeping of stained negatives. That is a fact. All else is anecdotal.

Not my fault. Sorry guys.

PE

Gerald C Koch · Apr 17, 2015

DREW WILEY said:
I've been routinely developing numerous kinds of film in pyrogallol for about 25 years now and haven't noticed any loss of stain in even my earliest negs. That might not be much of a track record in the overall scheme of things, but at least in terms of being able to predict printing
quality in my own remaining career it certainly is.

The brown stain produced by pyrogallol is probably more stable than the dyes produced by catechol. It consists of humic acid. If you have ever tried to remove the brown stain left by spent developer from plastic developing trays then you are familiar with this material. The stain is very hard to remove. Humic acid is the end product of the oxidation of various phenolic developing agents such as pyrogallol, hydroquinone and catechol. Another source of humic acid is from rotting vegetation which produces tannic acid which is a form of humic acid.

My point being that the stability of the pyrogallol stain does not necessarily carry over to that produced by catechol. So you cannot predict the stability of a catechol stain image on the basis of the longevity of pyrogallol stain images. It all has to do with the relative size of the molecules as evidenced by the stain color.

http://en.wikipedia.org/wiki/Humic_acid

Ian Grant · Apr 17, 2015

I began using Pyrocatechin staining developers 40 years ago, initially using Ilford IT-8 which is a re-developement toner to give Olive tones. There's no detectable fading, the prints still have the distinctive olive tones caused by the stain.

The Pyrocatechin stain is very difficult to destroy and seems very stable. Negatives aren't stored in daylight and so light fading isn't an issue.

Ian

Monday317 · Aug 13, 2015

+1.1

Gerald C Koch said:
I should qualify my previous post in that any fading must be uniform across the negative. That there was no uneven illumination on it during the fading. Of course the best thing is to avoid any fading in the first place.

I still have negatives from the 1978-1986 period that I stored in archival products from Light Impressions back then. They only get out if I'm printing them, which is rare any more. After returning to film this year, my first lab purchase was archival sleeves for the 6 x 9 negs I am making.

One cannot emphasize proper negative storage enough; it's really the only way to keep them stable, given the inherent chemical activity of the processes we use. Therefore, the suggestion would be to ensure a good storage system is in place before making any negatives so they can be stored safely. Properly processed, washed, and stored negatives should last at least as long as the photographer who created them...

Wayne · Oct 16, 2015

Is hydroquinone stain also from humic acid? Looks mostly brownish, maybe with a little red.

Gerald C Koch said:
The brown stain formed with pyrogallol consists of humic acids which are insoluble in water and should be quit stable. Other colors should be considered like the dyes in color film and they are subject to fading should the negative be exposed to light for long periods.

mrred · Oct 16, 2015

If longevity is your concern, you can always bleach and redevelop in pyro again. That will regenerate the stain.

Wayne · Oct 16, 2015

I'm mostly trying to squelch the concern that has cropped up on several occasions that HQ stain may not be as durable as others. Researching that topic brought me to this thread, which taught me that none of the stains are really considered permanent...so maybe its not an issue with HQ either. But facts are better than speculation. I don't use pyro and don't plan to.

mrred said:
If longevity is your concern, you can always bleach and redevelop in pyro again. That will regenerate the stain.

Gerald C Koch · Oct 16, 2015

Wayne said:
Is hydroquinone stain also from humic acid? Looks mostly brownish, maybe with a little red.

Yes, humic acid is the end products of most developing agents when they oxidize. Remember that the term humic acid is loosely applied to a large number of products. The color depends on the average size of the molecules.

Pyrogallol vs Pyrocatechol Stain Over Time

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