Stand Developer Concentrations

[Kirk Keyes]

Then again, I don't mention my microdensitometer either...

Tom - are you joking about having a microdensitometer, or do you really have one? Could you describe it some and how you use it?

 

[Kirk Keyes]

As buffer capacity decreases, the production of hydrogen ion becomes gradually more and more significant in the overall reaction, and begins to have its own effect similar to bromide in edge effects. It does not 'drag' in the classical sense of 'bromide drag' due to the lighter nature of hydrogen ion, but rather it tends to diffuse further in all directions.

So maybe the hydroxide approach like Jay is using would be "better" for getting more edge effects due to the poorly buffered nature of hydroxide solutions? That also could explain why the Rodinal people seem to like it for this type of development?

 

[Kirk Keyes]

OK, but what is the relevance of this, for this discussion, to a developer that when mixed has a given pH, and at the end of devleoment has the same pH.

Based on one of your previous messages I assume that it has something to do with the pH in border areas of heavy and light densitities where the developer is exhausting more than in the general solution. But if so, specifically how does this relate to a developer that begins with a general solution of around pH 10.9 and maintains that pH throughout the development.

The relevance is that for two developers with the same pH, the one that is least well buffered may show different effects than the one that is better buffered when looking at the behavior of the developing agents at a microscopic level in the developer.

Especially when one starts to consider that these reactions are going on inside a gelatin matrix that is affecting the diffusion rate of reagents in and out of it, and then we go and do things like not agitate the solution that is in contact with the gelatin matrix to even further minimize the replenishment of fresh reagents into the gelatin.

Inside that gelatin, the pH of the developer soution will drop as the silver metal is reduced from the silver halide. So this is where the buffering capacity of the developer will come into play.

When the carbonate (or cabonate buffer) is present, the pH will change less when the supply of fresh reagents is limited because of the buffering capacity than when a hydroxide solution is present, which has little buffering.

Part of what makes carbonates (and phosphates) much better buffers when compared to hydroxides is that they have more than one negative charge on them. Carbonates have 2 negative charges, phosphates can have 3.

When you add acid to a hydroxide, you start to neutralize it. One acid (H+) added to one hydroxide (OH-) and then you get water, H2O. Ron mentioned that mixed salts do a much better job of buffering and have a higher buffering capacity is because they have the capacity of react with the added acid but not change the overall composition of the solution significantly.

If you have a solution of CO3-- (carbonate) with some HCO3- (bicabonate), and you add acid, you convert some of the cabonate into bicarbonate (H+ added to CO3-- gives you HCO3-). If you have sufficient excess of carbonate or bicarbonate in the solution, the ratio of the carbonate to bicarbonate does not change significantly with the addition of that acid. That's why a carbonate or bicarbonate solution is better buffered than a hydroxide solution.

The same goes for a pure carbonate solution. You add acid to it, and I think you can see it does not neutralize the carbonate. It forms bicarbonate. And then this starts to form a mixed salt and buffered solution.

The thing to watch out for is when you get the amounts of carbonate and bicarbonate in equal amounts. (I mean Normal concentrations here in the chemistry sense of the word "Normal", i.e. "equivalent" amounts, not "equal" molar or gram or percent amounts). When this happens, the solution does not have any buffering capacity, and the pH will drop quickly as acid is added to the solution. The solution is at an "equivalance point" where there are equal normal amounts of each buffering ion and the buffering capacity is lost.

Here's a link to a nice little method for determining alkalinity - that can show the buffering capacity of a solution. http://water.usgs.gov/admin/memo/QW/qw82.05.html

And another link that does a good job discussing alkalinity and buffering - http://www.advancedaquarist.com/issues/feb2002/chemistry.htm (note there is a typo in Eq. 1, the CO3 should be CO3--.) THis page also shows a titration graph of a carbonate solution that demonstrates how the buffering helps maintain pH as acid is added. Make sure you scroll down to wher he has the graphs for where he added sodium acetate to the water and see how well that addition buffered the water, and note the pH range the acetate was effective at.

And finally, some good titration curve examples that show the pH change at the equivalence point: http://www.chemguide.co.uk/physical/acidbaseeqia/phcurves.html

(Sorry about the more indepth than usual chemistry discussion for those that are not into this sort of thing.)

 

[Kirk Keyes]

TEA may be a good buffer

TEA is not considered to be a good pH buffer. At least not solutions that are TEA based only.

 

[gainer]

So maybe the hydroxide approach like Jay is using would be "better" for getting more edge effects due to the poorly buffered nature of hydroxide solutions? That also could explain why the Rodinal people seem to like it for this type of development?

Where is it written that more edge effect is better? Everything I have read about it is that some is good, but a point is reached where enough is enough and more is too much.

If you get too much in your negative, what can you do to undo it? Are we looking for a photograph that will be judged by the clarity and width of its Mackie lines? "Ooh, what nice Mackie lines" the judge said, without commenting on the subject matter and gradations.

Hydroxide or no, Rodinal is capable of infectuous development. Fine white lines become wider in photographs developed in Rodinal. This means that silver has spread from its appointed place in the negative during development.

 

[df cardwell]

Where is it written that more edge effect is better? GAINER

Obviously, then, enough is enough.

And to find out how much is enough, we practise.

Myself, I have a palette of developments for different looks. If the image will benefit from a exaggerated 'effects', I invoke it.

Not unlike a reed player having a selection of reeds. Our job is to know and control our tools, not to fret over the possibility of error.

Baudelaire said "Art is technique charged with emotion".

He also said "Intellect, of its own, is impotent to create anything".

And, yes, I'm just quoting Baudelaire because I can't think of anything useful to add !

 

[sanking]

The relevance is that for two developers with the same pH, the one that is least well buffered may show different effects than the one that is better buffered when looking at the behavior of the developing agents at a microscopic level in the developer.

Kirk,

That may be true. However, there is no way to know whether a well-buffered formula or a poorly-buffered formula will give the desired effects. This can only be know by empirically testing for accutance, after the fact. In fact, without being able to test specifically what is going on at the boundaries where exhaustion takes place, how can one really know the exact role of pH in the process? Virtually all of the research data to which people refer is specific to certain test conditions that may or may not apply to other situations.

It is perfetly fine to theorize that such and such a thing *may* produce the desired effects, but the only practical way any of us have to know this for sure is to test. I would be delighted to have some practical system of testing for accutance, and like you, would probably spend a good amount of money to have it. It would certainly allow us to quickly answer some important questions with empirical testing.

Sandy

 

[Kirk Keyes]

Where is it written that more edge effect is better?

I'm not making any judgement calls here, so I'm not going to draw the line in the sand (Mackie lines maybe?). But it seems to me that a lot of people use stand development to accentuate adjacency effects.

If you get too much in your negative, what can you do to undo it?

Good question. And if you don't get enough for your taste, what then as well. And what's your point, anyway?

Hydroxide or no, Rodinal is capable of infectuous development. Fine white lines become wider in photographs developed in Rodinal. This means that silver has spread from its appointed place in the negative during development.

So the Rodinal is doing infectious development when used for stand development, and it is not creating what are refered to as adjacency effects?

 

[Kirk Keyes]

However, there is no way for me to know whether a well-buffered formula or a poorly-buffered formula will give me the desired effects. I could only know this by empirically testing for accutance, after the fact.

Yeah, that's why I posed the question, to see if any observations had been made in that direction.

In fact, without being able to test specifically what is going on at the boundaries where exhaustion takes place, how can one really know the exact role of pH in the process?

Yes, we really are such amatuers when it come to the deeper questions.

It is perfetly fine to theorize that such and such a thing *may* produce the desired effects but the only practical way any of us have to know this for sure is to test it.

And since I've never done any stand development at all, I went looking to see if someone had tried this approach.

 

[sanking]

And since I've never done any stand development at all, I went looking to see if someone had tried this approach.

Kirk,

My point was not that it would not be productive to test for edge effects by increasing the amount of B solution in the working. You could do that, and compare the results to a negative developed with equal amounts of A and B, or with more A than B. If you did this carefully with the right subject, and developed all of the negatives to the same overall contrast, I believe you would be able to detect any meanginful differences in grain and sharpness if you were to enlarge a 6X6 neg about 10X.

However, my question to PE was this. What would the above test tell you about pH at the border areas of local exhaustion, if the bulk solution at the beginning and end of development has the same pH? One could speculate that the reason for an increase in sharpness from edge effects might be caused by a local reduction in pH at the border errors from poor buffering, but you could not really know that for a fact since the difference could also result from another mechanism.

Sandy

 

[Steve Sherman]

Where is it written that more edge effect is better? GAINER

Obviously, then, enough is enough.

And to find out how much is enough, we practise.

Interesting to note, back in May of 2004 I brought some Semi-Stand work to Michael and Paula's to show them the process first hand, they studied the various prints I had brought to show. There was one image I had shot in Zion NP which had some small leaf details, rushing water and some boulders. While I didn't volunteer that the negative was slightly under exposed, the print showed nicely probably due to Michael's Amidol water bath.

Michael commented that the print had a "Fractured look" about it. We both noticed that negative areas which had extremely low density actually lost minute detail with the Semi-Stand process. Also, I remember Sandy telling me he had developed a negative for four hours and the result was not useable, the increased ajacency effect was too great.

I still maintain that the beginning and ending densities are determined in the conventional way, shadows with exposure and highlights with exposure and development. The micro contrast which ultimately dictates the mid tones is a product of dilution, agitation and time and any number of combinations of the three.

Further, just about the time we get all the various tests complete to determine just what is happening the light will change and we're back to square one. So I would agree with DF with his quote And to find out how much is enough, we practice I would add, by making photographs.

 

[gainer]

I'm not making any judgement calls here, so I'm not going to draw the line in the sand (Mackie lines maybe?). But it seems to me that a lot of people use stand development to accentuate adjacency effects.



Good question. And if you don't get enough for your taste, what then as well. And what's your point, anyway?



So the Rodinal is doing infectious development when used for stand development, and it is not creating what are refered to as adjacency effects?

My point is that we seem to be trying to find a way to get the maximum edge effect rather than controlling the process to produce only the amount that is beneficial to the scene at hand. Others have found and reported that there is such a thing as too much.

If you are really interested in controlled edge effects, it would seem that ubsharp masking is the way to go. The edge effects, above what may be present from conventional development are controlled by the mask, of which you may make many different ones until You get the one you like best without changing the original negative. If you do not get enough adjacency effect in the original development, it can be increased. I have seen examoles that looked like pasted-up cutouts.

I presented, in the article "Salt to Taste" in P. T. some time ago examples of Rodinal's apparent infectuous development. What you see as edge effects can also have an effect on the widths of black or white lines. Part of the edge effect is due to overshoot on one side of an edge and undershoot on the other. So the answer is, it is not always easy to tell the difference between edge effect and infectuous development because the same phenomena are involved in both.

 

[gainer]

I'm not really drunk, but srunk. Ubsharp is next to unsharp and examoles are next to examples.

 

[Kirk Keyes]

While I appreciate your suggestion that unsharp masking is a more flexible approach to increasing edge effects, I would also suggest that if one can achieve a similar effect in a single step, then that approach is just as useful, maybe more so. And masking has a whole different set of issues that one must learn. It all depends on your final goals as to which approach to pursue, right?

I've got all your PT articles - I'll see if I can find the Salt to Taste one and look into it.

"So the answer is, it is not always easy to tell the difference between edge effect and infectuous development because the same phenomena are involved in both."

I assume you mean visual phenomena, because my understanding is that they are two completely different chemical effects involved with edge effects and infectious development.

 

[sanking]

My point is that we seem to be trying to find a way to get the maximum edge effect rather than controlling the process to produce only the amount that is beneficial to the scene at hand. Others have found and reported that there is such a thing as too much.

Pat,

I think you may be misunderstanding what Steve and the rest of some of us are doing. We are not trying to get maximum edge effects, but in fact get the maximum amount of effects that is appropriate for the scene with the goal of making a sharp photography of pictorial content.

In most of my own work I have found that minimal agitation (agitation every two or three minutes) or extreme minimal agitation (four agitation cycles) gives me all of the adge effects I need for subjects that have a fairly typical range of contrast from the shadows to the highlights.

What Steve is doing, however, is attempting to get separation from micro-contrast in scenes that have a predominance of mid-tones with little separation. For this he is looking for greater edge effects that others might find appropriate for a pictorial rendition of a scene. At least, that is my understanding of what Steve is trying to achieve.

There is no doubt in my mind but that some developers are too sharp for normal scenes, so the goal is not to get maximum sharpness, but to get the maximum sharpness that still gives good pictorial rendition.

Sandy

 

[df cardwell]

If you are really interested in controlled edge effects, it would seem that ubsharp masking is the way to go.

Yes it would.

Sadly, I shoot mainly 35mm and have delusions of printing like Strand.

Being able to do what Adams taught, to make a negative that leads directly to the manifestation of my visualisation, is all that is left to me: no Photoshop, no unsharp masking, no SLIMT. SLIMTing. Whatever.

And the tools exist, are reliable and predictable, and effective. Even if we don't know exactly how they work !

 

[Photo Engineer]

Guys, here are some observations on your collective comments.

1. The HBr (hydrobromic acid) released during development is a strong acid. Ascorbic acid and hydroquinone (and their derivatives) are weak acids.

2. In a poorly buffered developer vs a well buffered developer, the overall solution pH may stay at the original value, but the local pH during development in a poorly buffered developer has actually been measured by using a surface contact micro pH meter, and has been found to become quite acidic during development. The alkali cannot diffuse in fast enough to make up for the HBr released by the developing AgBr. In the well buffered developer, the local pH is equal (roughly) to the solution pH throughout due to the good buffering. Therefore, pH induced effects are more strongly observed in the weakly buffered developer.

3. Observations above about loss of detail with increased edge effects are again reflected in my comments that micro contrast varies with the size of detail in images or the degree of magnification, and therefore reflects our visual impression of sharpness. The image may be getting 'sharper' due to increased edges, but the contrast of the image is getting so low that we cannot see the sharpness gain.

This is all part of a complex of problems related to the formulation and use of new developers, as they tend to vary with film type, halide ratio, magnifiation, agitation, buffer capacity, pH ... Well, you get the point (perhaps).

When all is said and done, more is said than done on this topic.

As Kirk said before, we need standards to talk rationally about these subjects. Otherwise it is just opinion. I have personally carried out many of these experiments measuring micro pH, buffer capacity, and edge effects vs magnification. I have sitting next to me a reprint of the article in the SPSE journal by Kriss on part of this topic, and the chapter in Mees regarding this topic (micro vs macro image structure and edge effects). They both show the problem clearly. I recommend them to you rather than PT magazine articles. The ones I refer to have hard data and Mees includes observational studies of pictures (albeit without the pictures, just the micro lines and data).

PE

 

[gainer]

While I appreciate your suggestion that unsharp masking is a more flexible approach to increasing edge effects, I would also suggest that if one can achieve a similar effect in a single step, then that approach is just as useful, maybe more so. And masking has a whole different set of issues that one must learn. It all depends on your final goals as to which approach to pursue, right?

I've got all your PT articles - I'll see if I can find the Salt to Taste one and look into it.

"So the answer is, it is not always easy to tell the difference between edge effect and infectuous development because the same phenomena are involved in both."

I assume you mean visual phenomena, because my understanding is that they are two completely different chemical effects involved with edge effects and infectious development.

The requirements for infectious development are met in lithographic developers, which generally have high alkalinity and little or no sulfite. Infrctious development is also most likely to occur in films with flat grains in thin emulsions. I could not, and did not say that the narrowing of lines in prints from Rodinal negatives was definitely due to infectious development, but that it looked that way. Rodinal does have high activity, high alkalinity and not much sulfite. Infectious development is a chemical edge effect.

If you don't mind an anecdote that is a little humorous, when I first began at NACA, we used oscillograph recorders to record on rolls of film time histories of the aircraft state measured in flight during experimental maneuvers. The pertinent sections of these records had to be copied on lithographic film to make printing plates for publication. In the lith process, narrowing of lines and dropping out sometimes occurred. It was common for someone to have to use an etching knife to restore parts of traces, this someone usually being in the photo section. One day, an engineer looking at proofs found a time history that went backward in time at one place. From then on, only engineers retouched line dropouts for technical reports.

 

[Photo Engineer]

Development of unexposed grains near developing exposed grains is termed infectious development. It has been linked to aerial oxidation and to some accelelerants.

However, it has been shown that developers whose reaction products are accelerants produce less infectious development with time, but those whose reaction products are fogging agents produce more infectious development with time.

Infectious development generally counteracts chemical adjacency effects by either broadening line exposures as the 'infection' spreads, or raising fog and thereby decreasing discrimination.

PE

 

[gainer]

Development of unexposed grains near developing exposed grains is termed infectious development. It has been linked to aerial oxidation and to some accelelerants.

However, it has been shown that developers whose reaction products are accelerants produce less infectious development with time, but those whose reaction products are fogging agents produce more infectious development with time.

Infectious development generally counteracts chemical adjacency effects by either broadening line exposures as the 'infection' spreads, or raising fog and thereby decreasing discrimination.

PE

Photograph a resolution test chart and develop the negative in Rodinal according to the manufacturers instructions. Contact print the negative. Tell us if the black lines in the print are narrowed and the spaces between them are widened. If they are, tell us whether that is due to adjacency effect or infectious development.

 

[gainer]

Guys, here are some observations on your collective comments.
I recommend them to you rather than PT magazine articles. The ones I refer to have hard data and Mees includes observational studies of pictures (albeit without the pictures, just the micro lines and data).

PE

Especially the ones you have not read. It is obvious that you have no idea what I presented in my articles, or how I presented it. If you haven't read them, or cannot understand them, do not criticize them.

HBr is indeed a stong acid. How long does it remain HBr in an alkaline solution, even locally? If it is so strong, why are the products of development by hydroquinone basic? In a developer with a carbonate as alkali, one molecule of carbonate neutralizes two molecules of HBr. So what? What would all of your quotations mean in the face of experimental evidence to the contrary?

Philosophically, the argument from authority is not the strongest argument, yet that is the argument you use against my reports that you have not even read.

 

[Photo Engineer]

Patrick, above you appear to state that oxidation products of ascorbic acid are strong acids.

Quote by Gainer "Not as much as the ascorbates. A product of development by ascorbic acid is the dehydroascorbic acid whiich is more acidic than ascorbic acid, as well as the hydrogen bromide, etc."

They are not.

Hydrobromic acid produced by development in all developers from the film is far stronger than the ascorbate or its byproducts.

The arguments that I present about edge effects and infectious development are from Mees and reputable scientific journals, not from a magazine and include quantitative data.

As for my understanding of your position regarding your publications, just like others who are reading only this thread, we will be judged by what we write here, not what is elsewhere. I can give all of the quotes to Mees or the journals I want but unless you or others read them you will not understand or believe. Have you ever read Mees or Mees and James?

I assure you that I have run quantitative experiments backed up by picture data. The results are not always clear cut due to the difficulty of separating pH effects from halide effects, but there is both a buffering power effect and an edge effect by halide and the items I cite above are real and powerful in photography. They cannot be dismissed by saying "I have published an article". Well, I've also published articles myself.

Kirk has raised valid points regarding standards, gathering meaningful data, and about edge effects and buffer effects. I have merely attempted to point out all of the factors involved in this, and then explain buffer capacity as requested by Sandy.

PE

 

[Ole]

Hydrobromic acid produced by development in all developers from the film is far stronger than the ascorbate or its byproducts.

Hydrobromic acid is a pointless sidetrack. What is formed is H+ and Br- ions, since hydrobromic acid would be completely dissasociated in aqueous solution at all realistic pHs. Two H+ (or H3O+, if you want to be correct) will neutralise one CO3--, while the Br- is simply Bromide.

 

[gainer]

Patrick, above you appear to state that oxidation products of ascorbic acid are strong acids.

Quote by Gainer "Not as much as the ascorbates. A product of development by ascorbic acid is the dehydroascorbic acid whiich is more acidic than ascorbic acid, as well as the hydrogen bromide, etc."

They are not.

Hydrobromic acid produced by development in all developers from the film is far stronger than the ascorbate or its byproducts.

The arguments that I present about edge effects and infectious development are from Mees and reputable scientific journals, not from a magazine and include quantitative data.

As for my understanding of your position regarding your publications, just like others who are reading only this thread, we will be judged by what we write here, not what is elsewhere. I can give all of the quotes to Mees or the journals I want but unless you or others read them you will not understand or believe. Have you ever read Mees or Mees and James?

I assure you that I have run quantitative experiments backed up by picture data. The results are not always clear cut due to the difficulty of separating pH effects from halide effects, but there is both a buffering power effect and an edge effect by halide and the items I cite above are real and powerful in photography. They cannot be dismissed by saying "I have published an article". Well, I've also published articles myself.

Kirk has raised valid points regarding standards, gathering meaningful data, and about edge effects and buffer effects. I have merely attempted to point out all of the factors involved in this, and then explain buffer capacity as requested by Sandy.

PE

I see that I should have been more clear. Development by ascorbic acid produces both HBr and dehydroascorbic acid. It is the combination of these that makes the byproducts of development more acidic than those of development by hydroquinone.

Are the writings of Ryuji Suzuki also to be considered as unworthy of regard?
And what is a tehcnical journal? How do you distinguish between its reports and those from a technical journal without reading both? A number of us who contribute to APUG have also written for Photo Techniques. So I presume you will continue to be stiff necked and refuse to look at what experiments and analyses I have presented elsewhere.

I have read and own my own copy of the third edition, 1969 printing of "The Theory of the Photographic Process." I own and have read Ferguson's "Photographic Researches of Hurter and Driffield" thanks to my friend Nicholas Twist. I have a copy of "The principles of Optics" by Hardy and Perrin. I made extensive use of this during my researches in the field of Simulation and Human Factors at NASA Langley Research Center. Believe me, I know and practice the Scientific Method. I presented a paper at MIT during one of the annual meetings of the Human Factors Society on Manual Control, which we called "Annual Manuals", on an application of information theory to measuring human performance.

 

[Photo Engineer]

Quote by Patrick Gainer "I see that I should have been more clear. Development by ascorbic acid produces both HBr and dehydroascorbic acid. It is the combination of these that makes the byproducts of development more acidic than those of development by hydroquinone."

The Hydrobromic acid is so far and away stronger an acid than either dehydroascorbic acid or any oxidation products of hydroquinone that it overwhelms the equations when done on balance. One mole of HBr is much stronger than one mole of dehydroascorbic acid. It is like comparing elephants to mice because they are grey and have 4 legs.

Dehydroascorbic acid has a pKa of 3.90, and is converted to ascorbic acid by sulfite ion. (therefore it is probably reacting immediately with sulfite forming sulfate and ascorbate in the developer - see Merck index 12th Edition, item # 2920 for details)

The pKa of hydrobromic acid is, of course, not reported as it is a strong acid, but I would judge it to be at least 3 orders of magnitude more acidic than the ascorbate. The local concentration of HBr during development is very large as I reported in a previous post.

If you don't wish to believe Drs. Mees and James regarding these things, particularly image structure, I direct your attention to "Photographische Informationsaufzeichnung" by Prof. Dr. Hellmut Frieser, in particular his chapter #3, "Wiedergabe Kleiner Details". For those unfamiliar with German, this is "Photographic Information Recording" and the chapter is "The Reproduction of Small Details". This chapter with charts, graphs, data and pictures gives a complete description of much of what we have been discussing regarding micro detail.

As far as I know, no organic acid used in photographic processing is as strong as any mineral acid. All alkali metal salts of these same organic acids are weakly basic, but alkali metal salts of the mineral acids are neutral.

Just as a point of reference, I suggest you consider a piece of film with 2000 mg / meter square of AgBr (0.0106 moles per square meter). Now, assume the swollen thickness is 0.05 mm. Calculate the moles per square meter of HBr released in this volume and then calculate the amount of Na2CO3 present and ascorbate present if the carbonate is at 50 g/l and the ascorbate is at 5 g/l. Doing this may be interesting to all of us. I am sure you will be surprised at the answer.

PE