Modern Rodinal Substitutes Part II

[gainer]

Vit C formulas may contain undissociated metol carbonate if there is such a thing,IDK.
Ascorbate probably does not form undissociated compound with metol which would be present as its aminophenolate.

The apparent superadditivity between Metol and ascorbic acid seems to be due to the ascorbate's ability to regenerate Metol. It is acting more as an antioxidant if that is true than as a developing agent. This is not my theory. I happened across it in Mees & James "The Theory of the Photographic Process" , fifth edition, third printing, 1969. I didn't see any speculation in that reference about the aminophenolate being formed in those experiments.

 

[Alan Johnson]

I dont think there has been much discussion of the form in which developing agents exist in solution.
Metol is methyl p-aminophenol sulfate.In sodium hydroxide(Metolal) it may form sodium methyl p-aminophenolate.In Rodinal is potassium aminophenolate.Metolal and Rodinal are chemically similar,may have similar tonality.
In Vit-C developers with carbonate it may be the metol exists in solution partly as a different compound,not sodium methyl p-aminophenolate.They are less likely to be Rodinal-like.
In sodium hydroxide+sodium ascorbate its anybodys guess in what form the metol exists,but it favours my case that it should be aminophenolate so I'll stick with that.

 

[gainer]

I dont think there has been much discussion of the form in which developing agents exist in solution.
Metol is methyl p-aminophenol sulfate.In sodium hydroxide(Metolal) it may form sodium methyl p-aminophenolate.In Rodinal is potassium aminophenolate.Metolal and Rodinal are chemically similar,may have similar tonality.
In Vit-C developers with carbonate it may be the metol exists in solution partly as a different compound,not sodium methyl p-aminophenolate.They are less likely to be Rodinal-like.
In sodium hydroxide+sodium ascorbate its anybodys guess in what form the metol exists,but it favours my case that it should be aminophenolate so I'll stick with that.

I did part of that last thing once. I compared hydroquinone-sulfite-hydroxide-bromide with ascorbic acid-sulfite-hydroxide-bromide for graphic arts. The results were quite similar. Don't remember much about it, but used it once to do a simulated line drawing of conductor Russell Stanger for the Norfolk Symphony's program booklet from a photo I took of him. There was no Metol, but it shows the developing power of ascorbate as sole agent when pH is high enough. Both needed great gobs of bromide to keep fog away.

 

[Kirk Keyes]

Guys - for determining what happens to what in solution, maybe you'd like to review the following terms:
Ampholyte
Zwitterion
Isoelectric point
pKa

 

[gainer]

You mean for predicting what happens. Sooner or later, you have to try it, why not sooner? There are times when one learns more by trying something and then searching for the reason it didn't work. I learned more about integration by parts by trying to use a published equation that had an error. It turned out to be a typo, but I had to go through the pertinent aerodynamic equations to find that it was a misplaced absolute value sign.

 

[Kirk Keyes]

I mean for both predicting and understanding why it happens.

When something that doesn't dissolve when it is believed that it should, well, maybe there's something missing in that original belief...

And using good sources is important, too, as you pointed out.

 

[gainer]

I don't know how we got on this path. Once upon about 30 years ago, I was first chair oboist and "principal photographer" for the Norfolk symphony. It was in the musician's union contract, would you believe? I had a good shot of the conductor that the board wanted to posterize and use on posters. I had a recipe for the necessary developer but no hydroquinone, so I tried ascorbic acid and it worked, but not without expectations. I had access to a lot of books on every conceivable subject and I did know how to read. My Daddy taught me at the age of 5.

 

[gainer]

I am working on a set of experiments that may lead somewhere on the Rodinal trail. I made a solution of p-aminophenol base in glycerine such that 10 ml of it would contain the amount of p-aminophenol that is probably in 1+50 Rodinal working solution. Exactness is not critical at this stage. Adding enough KOH to make the pH over 12 makes it as black as a coal mine at midnight with the hatches down, but develops HP5+ in 16 minutes at 70 F, which is about what the Germans would put on their chart if they believed in CI < 0.65. Next, I made the same solution but added the 7.9 grams of K2SO3 that one would get in the working solution by adding 384 grams per liter of stock, again making pH over 12. 9 minutes now gets normal contrast. I don't know how much enlargement it would take to make a significant difference in grain or gradation. 30X hasn't done it for me.

Back to the dungeon.

I still need a comparison to something like D-76.

 

[Ray Rogers]

I mean for both predicting and understanding why it happens.

When something that doesn't dissolve when it is believed that it should, well, maybe there's something missing in that original belief...

Kirk,

Is there anything you know about these (Ampholyte, Zwitterion, Isoelectric point) that specifically relates to Metol, Rodinal, or Developers in general?

That is, can you give some real world examples so we can learn something?
(I agree with the concept... but I don't have the skills just now to apply them to developers) can you show us what you mean with a practical example?

Thanks,

Ray

 

[Photo Engineer]

Ray;

With a simple google, you find: http://en.wikipedia.org/wiki/Zwitterion

You cana do the same with the others. However, I explained and posted a graph regarding Isoelectric Point with regard to gelatins some time back.

PE

 

[Ray Rogers]

I explained and posted a graph regarding Isoelectric Point with regard to gelatins some time back.

PE

Yea,
I was just wondering if Kirk had something specfic in mind.

 

[Kirk Keyes]

That is, can you give some real world examples so we can learn something?
(I agree with the concept... but I don't have the skills just now to apply them to developers) can you show us what you mean with a practical example?

I wasn't trying to imply anything specific to developers per se, but any chemical with both base and acid functionality on the same molecule in general. Things get more complicated with these kinds of chemicals. It can answer how they will ionize (and perhaps dissolve/not dissolve) based on the pH of the solution.

 

[Ray Rogers]

I wasn't trying to imply anything specific to developers per se, but any chemical with both base and acid functionality on the same molecule in general....

Understood...

Thanks Kirk

 

[gainer]

1. Take 500 ml water. Add 1 gram p-aminophenol base. Load the developing tank and be ready to pour before adding 5.2 ml of a 10% KOH solution. The solution will turn very dark very soon after the KOH is added and stirred in. Developing time for HP5+ at 70 F is 18 minutes.

2. Repeat the above but add 15 to 20 ml of the 45% K3SO3 solution before adding the KOH. Developing time for HP5+ is now 9 minutes. This is not due to difference in pH but to the anyioxidant effect of the sulfite.

The attachments show that overall grain and acutance are not observably different with or without sulfite. The scans are from real photographic prints. I copied out the detail pictures before reducing the file size of the overall pictures so one should be able to see the detail in "The Silver Chalice." Also, there is an aluminum-framed window screen standing behind the armchair that makes a good measure of resolution. The virtue of adding a lot of sulfite to the stock solution will be mostly in preservation. Even the 384 grams/liter proposed by Ian produces only about 7.5 grams/liter in the working solution at 1+50 dilution.

I have not yet tried adding bromide or EDTA.

 

[Photo Engineer]

There is a substantial difference between 2 and 3 Patrick.

PE

 

[gainer]

There is a substantial difference between 2 and 3 Patrick.

PE

What differencr caught your eye?

 

[gainer]

Let's do it this way. You tell me which of these had the sulfite. And if it seems vry obvious to you, remember that these are, if you view or print them to 10" height, 32 X magnifications of 35 mm HP5+ frames. Also, I intend to do other values of sulfite between 0 and 380 grams per liter to see if there's a break point at which the developer activity takes a jump.

 

[DutchShooter]

After reading almost all 40 pages on this topic, I've learned a lot about Rodinal (my favorite developer, especially with rollei retro 100 of which I have lots).

Gainer, the left two crops in your last post look better to me (and picture nr 3 in your previous post). Seems like quite a bit of difference to me?!

 

[Photo Engineer]

Patrick, I am just commenting on the differences. The left of the two is higher in contrast or slightly lighter in the highlight areas and the one on the right is darker and lower in contrast. That makes comparison, for me, more difficult.

PE

 

[gainer]

There is an artifice that will occur in periodic sampling such as digitizing when the original signal has frequency higher than the sampling frequency. The higher frequencies are folded back to the low end. The effect in a photograph with any amount of grain can make the grain look coarser than it would when viewing the photo directly. I was a bit sloppy in the post with the three images in that I did not get the same number of pixels per centimeter in both detail crops. I resampled the detail croppings at 2400 PPI for the most recent post. These are the same two negatives.

 

[Photo Engineer]

And, they show the same density / contrast differences I saw in the first three samples. I don't care which is which, I just have trouble judging image quality due to those density / contrast differences. As far as the effect you cite, this is why color negative sometimes looks grainier than color reversal. The color neg has such fine grain that you get artifacts.

PE

 

[Kirk Keyes]

Let's do it this way. You tell me which of these had the sulfite.

Print C has more contrast than Print D, so C appears to be sharper. But how can you really be sure if the prints don't truely match?

Thanks for reposting them so they are the same size.

 

[Kirk Keyes]

There is an artifice that will occur in periodic sampling such as digitizing when the original signal has frequency higher than the sampling frequency. The higher frequencies are folded back to the low end. The effect in a photograph with any amount of grain can make the grain look coarser than it would when viewing the photo directly.

So are you saying one of the scans does not truly represent the print, or are you just unloading a bit of BS on us?

 

[gainer]

So are you saying one of the scans does not truly represent the print, or are you just unloading a bit of BS on us?

That BS as you stupidly call it is and always has been very important in almost any branch of science, except possibly the one that defines BS. You will find it and much else you might find useful in "Information Transmission, Modulation and Noise" by Mischa Schwartz. It's in the McGraw-Hill Electronic Engineering Series.

I am saying no scan that I can get through to APUG in my lifetime with my 26.4K internet service can truly represent any print. I am also syaing that if it takes a 32 power enlargement to show any appreciable difference, then the difference has no practical meaning to me.

I also described my experiment in sufficient detail that you can repeat it in your own dark place and show me what you think I should have found.

Why do you act as if you believe I am trying to sell you something?

 

[Photo Engineer]

Patrick;

Would it be too much to ask if the two photos matched in contrast and density? That is my only reservation.

PE