Enhanced stain with Pyrocat HD

[couldabin]

Gordon Hutchings' "Book of Pyro" says that an alkali solution (1/2 tsp sodium metaborate per litre of water) for 2 minutes following fixing can induce formation of stain. Three questions -- a) Rinse off the fix before putting the film into the alkali solution? b) Can the alkali solution be re-used? c) If so, how long should it keep?

Thanks.

 

[Raghu Kuvempunagar]

Surest way to increase image-wise stain is to bleach the negative in a rehalogenating bleach such as Ferricyanide+Bromide and redevelop in Pyrocat HD.

 

[Alan9940]

The after bath is no longer recommended. If you want a more robust stain with Pyrocat-HD, you can use a 2:2:100 dilution. Generally, though, this dilution is used to create negative density needed for alt printing or for Azo type silver papers.

 

[couldabin]

Thanks for the updates on staining. I may experiment with a less dilute working mixture. Appreciate the insights.

 

[pentaxuser]

Can you say what you think the benefits of an increased stain will be?

Thanks

pentaxuser

 

[couldabin]

More nuanced density.

 

[pentaxuser]

Thanks, duane and michael_r, It would be interesting to see two prints from two negs of the same scene in the same light conditions to see how much of nuanced density improves the print

pentaxuser

 

[john_s]

Thanks, duane and michael_r, It would be interesting to see two prints from two negs of the same scene in the same light conditions to see how much of nuanced density improves the print

pentaxuser

In one of Barry Thornton's books there's an example of that. My copies are away and I'm in Covid lockdown so I can't check. From memory, it was comparing PMK to a conventional developer. It was a beach scene and the prints were made on VC paper. As you know, the stain simply adds density and contrast if graded paper is used. For VC paper, the stain is modifying the filtration that determines the print contrast. PMK stain is somewhat green and in BT's example the print had insufficient contrast in the highlights.

My PMK negs were never as green as some that I've seen on the internet, and I didn't experience the poor highlights. Less highlight contrast could be of benefit in some cases, of course.
I now use Pyrocat-HD because I find it more versatile and incidentally its stain is less likely to interfere to that degree with VC papers. I find that contrast control with Pyrocat-HD is more predictable because it doesn't die during development as PMK does.

 

[Raghu Kuvempunagar]

Can someone explain to me how a stronger dilution of Pyrocat HD is going to produce more stain if the film is developed to the same contrast as with 1:100 dilution? Is there a variant of Pyrocat that skews stain density significantly over silver density while producing negatives of the same contrast as 1:100?

 

[Ian Grant]

Hutchings later said he thought the alkaline after bath only added base (ie non-imagewise) stain and no longer advised doing it.

While I don’t know of a mechanism by which this would work, I have not seen objective evidence for or against. There is/was such a thing as latent tanning, but not related to dye formation.

The original suggestion was to keep the used developer and place the fixed partially washed negative back in it, this definitely just increased base stain and probably had detrimental affects ast the additionalstaining could be uneven.

I can't speak for PMK and Pyrofallol stain as I've never wanted to use it but with Pyrocat HD once the stain is created during development it is very stable, it is not affected by Stop bath or choice of using an Acid fixer. I use an Ilford paper tone IT=8, essentially a Bichromate re-halogenating bleach (which is also an Intensifier), this uses a simple Pyrocatechin/Carbonate re0developer which has a bery short tray life, the effects are Olive brown prints quite different to sepia toners. As I have Pyrocat HD on the shelf I've used it as the re-developer and the results are the same.

Using old test strips and scrap prints I've tried various chemicals and can't reduce the staining once created, also I tried testing the effects of sop baths and fixers andthey made no difference.

Can someone explain to me how a stronger dilution of Pyrocat HD is going to produce more stain if the film is developed to the same contrast as with 1:100 dilution? Is there a variant of Pyrocat that skews stain density significantly over silver density while producing negatives of the same contrast as 1:100?

Generally higher concentrations are used to increase contrast and the Dmax for alternative processes, however there's also som esubtle differences which are hared to describe.

If we take a simpler high dilution developer like Rodinal then the best way of controlling contrast is dilution rather than time a negative processed to the same Dmax at 1:25 has more contrast than one processed at 1:50, it's similar when printing as well. It's the effects of diffusion and localised exhaustion. In addition grain size incres with higher concentration and that also affects staining.

Ian

 

[pentaxuser]

Yes key to this is the question that couldabin asked:
Gordon Hutchings' "Book of Pyro" says that an alkali solution (1/2 tsp sodium metaborate per litre of water) for 2 minutes following fixing can induce formation of stain.

Does this increase stain for Pyrocat HD. If it does then based on the rest of his opening post and his answer to me it appears that he is convinced that it is beneficial(rightly or wrongly) and all he really needs is the answers to his 3 questions that followed his opening that I quote above.

We can stray into a discussion about what a staining developer confers compared to a non staining one but that may not add anything to the nub of the thread

pentaxuser