Modern Rodinal Substitutes Part II

[Ian Grant]

Apologies for having to start a new thread but I can't read or even access the first to reply to posts.

So with a bit of telepathy

Originally Posted by Kirk Keyes

Well, there's a problem there, as it's really hard to measure pH accurately when it gets much above 12.5 or so. You have to start getting special electrodes and the like.

But for MSDS work, it doesn't have to be too precise.
__________________
Kirk

A point that's being missed is that A&O give a figure of 2.7% Potassium Hydroxide not 3% in older Agfa MSDS.

The pH is around 14 sure, but the actual requirement is the pH of the working dilute solution rather than the concentrate which is given elsewhere as pH 11.55, which I commented on in the first post of the thread.

Way back Ron (PE) mentioned adjustments to Rodinal before bottling, the question we need to ask is are they adjusting on the basis of the concentrate, or also doing some tests on a dilute sample, as this will be a far more accurate indicator.

Can someone please post a link to this continuation on the original post.

Ian

[Ian Grant]

Originally Posted by cmo

Can someone suggest a formula for high-acutance muesli?

Would you be able to design an environmentally friendly Rodinal substitute? Paramidophenol is a verifiable water pollutant and injurious to health.

I suddenly realised why you want a developer that's non injurous to health

More seriously I have had a thought and it might just work. Answering Kirk's pH point made me think of a developer I've used highly dilute and yes it gave excellent acutance etc and with modification it would almost be drinkable.

This quote came back to mind from earlier in the thread:


As for developers, it is probable that the next few years will see the introduction of a series of developing agents that that can actually be eaten if desired. Some, chemically related to Vitamin C, are available now though at enormous cost. One call almost see the advertisement of the new Zero-Grane 999 (1960 A.D.) ----- "Try Zero-Grane 999. Non-poisonous. Enlargement to 999 diameters, miraculously discovered by George Gizzlewski after 84 years of painstaking research. If it won't develop your negative, take two teaspoonsful after each meal. It puts spring in your step and a light in your eye. $10 per 2 oz. bottle sufficient for 89 rolls of film."


Edmund Lowe, 1939


Ian

[Kirk Keyes]

Link to old thread:
http://www.apug.org/forums/forum223/...bstitutes.html

[Photo Engineer]

Ian;

Of course something was going on in the old formula. I believe that in one post you mention that the concentrate had to sit for a while after final bottling. There were additions made and then a "hold for ripening" that the Rodinal underwent before sale. IDK what this involved, but I assume it had something to do with pH.

I say again that the adjustment in formulas may have been to track the changes in average emulsions from Agfa, Kodak and Ilford as they had much more surface iodide. This would entail some change in pH and bromide to tweak development and other paramaters.

PE

[Ian Grant]

Originally Posted by Photo Engineer

Ian;

I say again that the adjustment in formulas may have been to track the changes in average emulsions from Agfa, Kodak and Ilford as they had much more surface iodide. This would entail some change in pH and bromide to tweak development and other paramaters.

PE

I agree, and suspect that the big change with the addition of anti-foggants came with the emergence of 35mm film which happened much faster growth-wise in the German market, with the rest of Europe lagging slightly behind and even slower take up in the US.

But remember that Calbe RO9 is much lower pH and not much more than a 30% Potassium Sulphite solution would be. So really the pH change came in 1964.

Ian

[Alan Johnson]

Crawley BJP Jan6 1961 explained how high pH together with reduced concentration of the developing agent affected acutance in the case of metol."When the concentration of developing agency is lowered in this way...the non-availability of considerable supplies of fresh developer has some tendency...to prevent the image spread due to the infection of adjacent crystals."
IDK if this happens with p-aminophenol,it raises the question if post 1964 Rodinal is sharper than the previous version.

[Photo Engineer]

Alan;

It also depends on the film emulsion and the amound of bromide in the Rodinal (as well as other antifoggant).

In general, higher surface Iodide would increase apparent sharpness while Bromide or other antifoggant in the developer would tend to decrease apparent sharpness. Older films would be more sensitive to pH and developer concentration as per Crawley.

PE

[Ian Grant]

Some say the pre 64 version of Rodinal is far sharper others the opposite but at these low concentrations the film itself will have a very significant impact. Rodinal brings the best out of APX100 and Tmax 100 in my personal experience of nearly 20 years using Rodinal. In the 70's I tested these developers with the then industry standard FP4 which was and still is regarded as the best film of it's type available.

All I can say is that modern Rodinal with modern films is a superb combination, you can come see images that prove it, and many other UK workers in the 80's & 90's through to today are producing exquisite images using one of the simplest formula of any type.

an

[Alan Johnson]

Originally Posted by Photo Engineer

Alan;

It also depends on the film emulsion and the amound of bromide in the Rodinal (as well as other antifoggant).

In general, higher surface Iodide would increase apparent sharpness while Bromide or other antifoggant in the developer would tend to decrease apparent sharpness. Older films would be more sensitive to pH and developer concentration as per Crawley.

PE

PE;

I believe the theory is that Bromide liberated during development of a dense area diffuses laterally and inhibits development at area with lower exposure,thereby making the edge of this area still less dense and causing an adjacency effect.Bromide in the developer might swamp this effect.
Is that how your theory of bromide works or is there some different effect?

[Ian Grant]

it's the developer that exhausts and need relplenishing, the dev can have no bromide.

Ian