Hypo Clearing Agent and Pyro

[Hans Berkhout]

Pyro users: do you use Hypo clearing agent following fixing of your film? If so, why? At what strength (e.g. 1%, 2% solution) and how long? If you don't use it, why not?

Hypo clearing agent (Sodium sulfite in water) affects the stain of anti halation and pyro. Cole Weston used it on a number of his father's negatives (ABC pyro), Bob Herbst and Sandy King use

it as part of their pyrogallol or -catechine processing routine. Others, for instance Steve Anchell, advise against using it.

In responding please make clear if you refer to anti halation stain, pyro image stain, or pyro stain of film base plus fog.

I am interested in comments based on research and/or experience.

Thanks.

[IanG]

You don't really need to use a hypo clearing agent with films it has little to no effect, it's really far more beneficial with fibre based papers where the intermediary semi soluable silver thiosulphate compouds formed during fixing bond weakly with the cellulose in the paper base, there are complex equilibrium equations and the sulphite tips the balance toards better soluability.

There was a lot of mumbo jumbo about staining developers and the effects of acid fixers including the recommendation to soak the film after fixing and a short rinse in the spent developer. All the latter does is increase base staining :D.

My experience with Pyrocatechin staining developers for prints (as in Ilford IT-8 toner) is the stained image is remarkably stable and not affected by Hypam/Ilford Rapid fixer or a Sulphite HCA bath. I took things to extremes with scrap test strips etc and couldn't get the stain to reduce. The Ilford IT-8 toner is a Bichromate rehalogenating bleach followed (after a good wash) by a simple Pyrocatchin re-developer, these days I use Pyrocat HD as the redeveloper because it happens to be my main film developer and this was used for my tests.

Ian

[Taija71A]

Very Quick Answer:

Hans, I would base my determination/decision to use a HCA or not...
'Solely' depending upon what Fixer -- You are presently using.

Therefore, I personally do not use it... Only because with my TF-5 Archival Fix it is not necessary --
And IMHO it does not affect/benefit the 'base' Pyro Image Stain.
--
Hans, if you have not yet read the following Thread... It too may be of some interest to you:

http://www.largeformatphotography.info/forum/showthread.php?89011-When-to-use-hypoclear
--
Thank-you. Best Regards,

-Tim.

[Jim Noel]

I don't use Hypo Clearing Agent on any film with any developer. Since there is essentially no material present into which the thiosulfate might soak, I have never seen the need for this step. A good soaking wash with at least 5 changes of water has served me well for over 70 years. I don't have any stained or faded negatives.

[Doremus Scudder]

I use PMK as my standard developer. Since starting with it, I have never used a wash-aid (Hypo Clear) on the recommendation of Gordon Hutchings (who wrote the Book of Pyro). He states that the sulfite bath will remove the pyro stain. I've never tried it, so I don't know if that's true, however, I have totally removed the stain on a pyro negative when trying to selenium tone it; the stain simply disappeared. I now use bleach and redevelop to intensify stained negatives. The selenium intensification stripped the stain away and added just about enough density to replace it. Next time I have a discard neg or a test neg, I'll pop it in the Hypo Clear just to see if Hutchings was right. Maybe someone here has actually treated a PMK negative with wash-aid and has an answer?

As for anti-halation dyes: these almost always come off in the pre-soak or the development stage. The pink cast many negatives have is due to stubborn sensitizing dyes. I find an extended fix (I use Hypam or Rapid Fixer) removes the stain on the films I use (Kodak 320 Tri-X and TMY) with no need for a hypo-clearing bath. Fixing film a bit longer has no ill effects.

FWIW, as many have said, a wash-aid is not really needed for film. However, if you check out the sticky thread on film washing at APUG http://www.apug.org/forum/index.php?threads/film-washing-test.69416/ you will see that a wash-aid does speed things up a bit. Just make sure you are washing long enough. I wash for minimum 30 minutes.

Best,

Doremus

[IanG]

That's interesting Doremus, maybe the Pyrogallol stain is less stable than Pyrocatechin stain.

Ian

[Ken Lee]

Sodium Sulfite removes stain.

You can use it to clean grape juice or wine stains. It is a bleaching agent: see http://www.chemistryexplained.com/Ar-Bo/Bleaches.html

When using Pyrocat you can use it as a Hypo Clearning Agent (if needed) and you can use it to remove the magenta sensitizing dye of films like Kodak TMax if your fixer isn't fresh enough to remove it entirely. The danger is that you start to remove the pyro stain if you over-do it.

1 teaspoon per liter for 5-10 minutes at 20 deg C is a good mix.

[Bruce Barlow]

Sodium Sulfite removes stain.

You can use it to clean grape juice or wine stains. It is a bleaching agent: see http://www.chemistryexplained.com/Ar-Bo/Bleaches.html

When using Pyrocat you can use it as a Hypo Clearning Agent (if needed) and you can use it to remove the magenta sensitizing dye of films like Kodak TMax if your fixer isn't fresh enough to remove it entirely. The danger is that you start to remove the pyro stain if you over-do it.

1 teaspoon per liter for 5-10 minutes at 20 deg C is a good mix.

I don't use HCA, and as far as the pink cast, life's way too short to use tired fixer. What's another 50 cents to ensure several bucks worth of film, and priceless time to make negatives?

Just my 2 cents on top of the 50.

[Fred L]

I've been using Heico Permawash since the dawn of time and have used it for PMK negs and they still have that wonderful greenish-yellow hue. I know it's really not necessary with film but old habits yano ;)

[Hans Berkhout]

152549
Thank you all for your input.
My concern is that I might cause deterioration of the pyro image stain when diminishing or removing base+fog stain. Some in the pyro community use HCA routinely while others advise against it's use. That's why I started this thread, just curious.
I shouldn't have mentioned the anti halation stain, as Doremus explains it usually disappears during the presoak. I meant the bluish sensitizing dye.
As far as the use of HCA and non-pyro film developer- I don't use it after fixing. My negs from the 50's, 60's are still fine. Washed in tap water 20C, 15 minutes.
My solutions are always fresh. I buy sod. sulfite in 50 lbs bags, minimum purchase 2 bags- same for hypo. So feel free to contact me if your supplies are low.......

Ken 1 tsp HCA per liter seems a bit low, I wonder if you mean 1 tablespoon.

Thanks again.

[Doremus Scudder]

....

Ken 1 tsp HCA per liter seems a bit low, I wonder if you mean 1 tablespoon.

Thanks again.

Hans, I use one Tbsp. (tablespoon) of sodium sulfite per liter plus a pinch of metabisulfite when making my wash-aid. That is kind of "standard." I don't know if Ken made a mistake or if he is recommending a weaker dilution for film developed in a staining developer.

We still haven't had anyone chime in that has actually removed the pyro stain using sulfite... Anyone there?

Best,

Doremus

[Michael R]

Doremus, controlled testing would be required in order to manage the variables. The dyes formed (from developing agent reaction products) differ depending on the developing agent, and may also differ due to other compounds in, and characteristics of the formula. Even the emulsion may (or may not) play a role. Different dyes will have different stabilities. Then we have the issue of composition and pH of the HCA.

We know sulfite can prevent the initial formation of these dyes since it scavenges the oxidation products of hydroquinone, catechol, pyrogallol. But can sulfite remove all these particular dyes after the fact? All I've ever seen/read is anecdotal at best. Experiments would be required here. Even if we prove something for PMK, can't necessarily extrapolate to WD2x etc.

[IanG]

Doremus, controlled testing would be required in order to manage the variables. The dyes formed (from developing agent reaction products) differ depending on the developing agent, and may also differ due to other compounds in, and characteristics of the formula. Even the emulsion may (or may not) play a role. Different dyes will have different stabilities. Then we have the issue of composition and pH of the HCA.

We know sulfite can prevent the initial formation of these dyes since it scavenges the oxidation products of hydroquinone, catechol, pyrogallol. But can sulfite remove all these particular dyes after the fact? All I've ever seen/read is anecdotal at best. Experiments would be required here. Even if we prove something for PMK, can't necessarily extrapolate to WD2x etc.

Just to make things more confusing both Ilford and Kodak used Pyrogallol as an oxygen scavenger in commercial developers sold for large scale D&P processing.

Ian

[Doremus Scudder]

Doremus, controlled testing would be required in order to manage the variables. The dyes formed (from developing agent reaction products) differ depending on the developing agent, and may also differ due to other compounds in, and characteristics of the formula. Even the emulsion may (or may not) play a role. Different dyes will have different stabilities. Then we have the issue of composition and pH of the HCA.

We know sulfite can prevent the initial formation of these dyes since it scavenges the oxidation products of hydroquinone, catechol, pyrogallol. But can sulfite remove all these particular dyes after the fact? All I've ever seen/read is anecdotal at best. Experiments would be required here. Even if we prove something for PMK, can't necessarily extrapolate to WD2x etc.

Michael,

Same here; I've never used a wash-aid on a stained neg, so have no personal experience. Gordon Hutchings, however, recommends against using HCA because it would remove the stain. This, however, is still hearsay, as it seems there aren't many (if any) who have experienced pyro stain removal with wash-aid or they would have likely posted by now. As mentioned, I did once neatly and completely remove the PMK stain from a neg I was trying to selenium intensify, so I know that somehow, something will reverse the stain. I'm not sure if it was chemically altered or removed in the process.

I'm in the middle of a darkroom build this summer and won't be able to develop film again till Sept. At that point I'll test PMK with and without wash-aid and see. Maybe someone else can do this earlier.

Best,

Doremus