Synthesis of Rodinal Substitute (looking for help with the chemistry)

[Rudeofus]

This is excellent shelf life, and it is the shelf life which was always reported for Rodinal. I have myself witnessed a dark room buddy, who's one year old Rodinal clone turned completely inactive, as in "after developing in 1:25 as prescribed in massive dev chart, the negs came out completely blank". This incident, and many similar ones, make people wary of non-standard-issue Rodinal clones, and it's reassuring to read, that a batch of Parodinal held up for five years.

 

[Harry Stevens]

Trouble is a lot of people automatically blame a blank roll of film on their developer when there are plenty of other suspects...

 

[Rudeofus]

I can certainly exclude the usual suspects in this particular case, because we

1. saw no frame rebates on the film. Therefore I know it was a development process error, nothing to do with exposure
   
2. tried a test clip in room light in a fresh batch of developer - remained completely blank, too.

This bottle of Rodinal clone was dead after one year, and it was at least as dead as this parrot in that famous Monthy Python's sketch.

 

[Alan Johnson]

(!) If you try to make p-aminophenol from acetaminophen without added sulfite it darkens very rapidly in air which suggests that Rodinal (clones at least) will oxidize rapidly once the sulfite is all oxidized.
(2) There have been suggestions that Agfa Rodinal formula recent version contained an additional additive as well as sulfite to prevent oxidation. Mysterious properties were attributed to it, such as being able to slow the diffusion of dissolved oxygen. The matter was never resolved.

 

[Gerald C Koch]

(!) If you try to make p-aminophenol from acetaminophen without added sulfite it darkens very rapidly in air which suggests that Rodinal (clones at least) will oxidize rapidly once the sulfite is all oxidized.
(2) There have been suggestions that Agfa Rodinal formula recent version contained an additional additive as well as sulfite to prevent oxidation. Mysterious properties were attributed to it, such as being able to slow the diffusion of dissolved oxygen. The matter was never resolved.

The high salt (generic term not sodium chloride specifically) concentration to a large extent prevents oxygen from dissolving in the concentrate. Think about what happens if you add something like sugar (Mentos mints) to carbonated water. You get a lot of foam as the sugar forces the carbon dioxide out of solution.

 

[Gerald C Koch]

I can certainly exclude the usual suspects in this particular case, because we

1. saw no frame rebates on the film. Therefore I know it was a development process error, nothing to do with exposure
   
2. tried a test clip in room light in a fresh batch of developer - remained completely blank, too.

This bottle of Rodinal clone was dead after one year, and it was at least as dead as this parrot in that famous Monthy Python's sketch.

I had a similar experience with R09. It soon became black and tarry. I blamd the low density polyethylene bottle that it came in.

 

[Alan Johnson]

The high salt (generic term not sodium chloride specifically) concentration to a large extent prevents oxygen from dissolving in the concentrate. Think about what happens if you add something like sugar (Mentos mints) to carbonated water. You get a lot of foam as the sugar forces the carbon dioxide out of solution.

http://www.sciencedirect.com/science/article/pii/0013468667800070?via=ihub
I did not get the full text but this article supports Gerald's explanation for the long life of Rodinal, both the solubility and diffusivity of oxygen fall with hydroxide concentration. There seems to be no reason why the various clones should be much different, if that explanation is correct.

 

[Rudeofus]

Alan, take a look at this:

 

[chiller]

I do remember a discussion about whether the clone was to be made up as 200ml or 250ml. Mine was made to 200ml according to the spreadsheet I was provided by Dorff.

Panadol was on special last week for $1.90 per 100 tablets so I can see a new batch of Parodinal being made this weekend - either that or a new batch of shaving soap. They both need Potassium Hydroxide.