PaRodinal, 5 Years Later.

[David A. Goldfarb]

So again I revisited that batch from December 2019 after not using it for some months to check out some new repairs on the same camera I was testing three years ago (I think it’s working now), and it was definitely weaker. Negs came out thin—potentially scannable, but not enough density for decent conventional prints, and nothing worth the gymnastics of intensification and such. It’s likely that in our warm year-round Hawai’i climate that it doesn’t last as long as it seemed to when I lived in New York. So I mixed up a new batch, and things should be back to normal. I guess I’ll declare a 2-year limit on PaRodinal in the tropics, but maybe a few more years in cooler locations.

 

[Donald Qualls]

Two years is longer than I've ever tried to keep the stuff. Still, doesn't seem bad for a home-brew developer that, if you get a good price on the acetaminophen, might cost as little as a nickel a roll to use...

 

[David A. Goldfarb]

I'm still slowly working through a huge bottle of acetominophen that expired in 2015. What we thought we would do with 500 tablets, I have no idea, even if they were on sale. Yesterday's new batch at least consumed 36 tablets. We have a smaller, fresh bottle for our occasional headaches and fevers.

 

[Donald Qualls]

a huge bottle of acetominophen that expired in 2015.

Given how expiration is set on medicines, that 2015 expired acetaminophen is probably just fine. Certainly good enough for developer.

 

[David A. Goldfarb]

Yes, the new batch seems just fine.

 

[pentaxuser]

The OP, ZorkiKat, told us that his PaRodinal has lasted 5 yrs by 2011. I wonder how much longer it lasted? His may have been used up shortly afterwards but as he was selling it in Manila, one or more of his customers may have reported to him even long life than 5 years thus he may have a stock of useful info

A pity that he hasn't visited for about 14 months so this question my never get answered

pentaxuser

 

[Alan Johnson]

Vintage Chemicals

Here are three I found on ebay: (1) EIKONOGEN.This I read is similar to metol.It seems to have fallen out of use by 1930 probably because it cost more than metol and possibly does not keep as well. Hence it has never been used in newer formulas,D-76,Beutler,Microdol,Hutchings Pyro, various...

www.photrio.com

See "Azol" here, this was a Rodinal type with active developing agent aminophenolate.
When tested at 62 years old it still worked. This shows that aminophenolate does not react with water.
It suggests that so long as air is kept out of a glass bottle containing PaRodinal it will last just as long as the plastic stopper keeps air out. Any air that gets in is at first reacted with sulfite until that is all used up.

 

[Raghu Kuvempunagar]

It suggests that so long as air is kept out of a glass bottle containing PaRodinal it will last just as long as the plastic stopper keeps air out.

Would this depend on whether or not there is an excess of Sodium (or Potassium) Hydroxide in the concentrate? Rodinal clones like EZ-Rodinal use just enough Hydroxide needed to form Phenolates of p-aminophenol. PaRodinal, however, needs Hydroxide not only for Phenolate formation but also for deacetylation of Acetaminophen. Sreenath's original formulation suggested a specific amount of Hydroxide informed by molecular weights but didn't claim that it was optimal:

 

[Alan Johnson]

Would this depend on whether or not there is an excess of Sodium (or Potassium) Hydroxide in the concentrate? Rodinal clones like EZ-Rodinal use just enough Hydroxide needed to form Phenolates of p-aminophenol. PaRodinal, however, needs Hydroxide not only for Phenolate formation but also for deacetylation of Acetaminophen. Sreenath's original formulation suggested a specific amount of Hydroxide informed by molecular weights but didn't claim that it was optimal:

View attachment 313313

Yes, unlike Rodinal, PaRodinal does contain a large excess of hydroxide so the question of whether this may affect stability does arise. Since I kept the Azol, now 74 years old [it spent the last 12 years in a glass bottle with a plastic screw top], I measured the pH of it with paper, result pH~14. So it looks like this also must have an excess of hydroxide and after 62 years it did not affect stability.

 

[pentaxuser]

Wow, 62 years and still going! I take it that this is no longer produced for the same reason that light bulb manufacturers made sure the allegedly everlasting bulb inventor, after showing his invention, never made it out of the demonstration at the light bulb factory ?

pentaxuser

 

[Donald Qualls]

The Parodinal formula I used to use has the same proportions as the above cited "minimum" sodium hydroxide -- 15:50:20 acetaminophen, sulfite, and hydroxide.

 

[Raghu Kuvempunagar]

Yes, unlike Rodinal, PaRodinal does contain a large excess of hydroxide so the question of whether this may affect stability does arise.

Ok, this was also the opinion of Gerry Koch:

The problem with all these Tylenol based developers is that they cannot be made accurately. Traditionally Rodinal is made by "titrating" the paaraminophenol by adding 50% potassium hydroxide solution to a slurry of paraminophenol and potassium bisulfite. As hydroxide is added the solid begins to dissolve. To prevent any excess of hydroxide you stop adding hydroxide just before all the pap dissolves. With all the insoluble tablet binder present you cannot do this. So all there various preparations have an excess of hydroxide which effects their stability and activity.

 

[pentaxuser]

Ok, this was also the opinion of Gerry Koch:

It would seem that their stability and activity in at least one case here on Photrio may be affected after about 60 years but we can't be sure

It's the old story: Either some users are downright liars or are downright lucky. The former group can be ignored and the latter, a presumably tiny group, do not represent what a person with average luck can expect from this stuff

pentaxuser

 

[Donald Qualls]

Either some users are downright liars or are downright lucky. The former group can be ignored and the latter, a presumably tiny group, do not represent what a person with average luck can expect from this stuff

Still, I'm pretty confident in six months on a bottle of Parodinal, and when I was using it regularly, that was about how long it took to use up a batch. The only way I can see the difference between six months, two years, and five years of bottle life mattering is if you made way too much in a single batch, or don't like the stuff well enough to use it regularly.

 

[Alan Johnson]

It would seem that their stability and activity in at least one case here on Photrio may be affected after about 60 years but we can't be sure

It's the old story: Either some users are downright liars or are downright lucky. The former group can be ignored and the latter, a presumably tiny group, do not represent what a person with average luck can expect from this stuff

pentaxuser

It's not down to luck. It depends how much the PaRodinal is exposed to air.
I was merely pointing out that if it is not exposed to air at all it should last indefinitely.

 

[pentaxuser]

It's not down to luck. It depends how much the PaRodinal is exposed to air.
I was merely pointing out that if it is not exposed to air at all it should last indefinitely.

I don't disagree, Alan and it was not an attempt to suggest you were lucky. The quote made by Raghu was one from Gerald Koch whose last sentence, taken at face value, seems to suggest that PaRodinal's stability and activity are inevitably affected. Thus from that quote it seemed to me that a reasonable conclusion from anyone reading it would have to be that anyone not being affected by changes in stability and activity with a 60 year old PaRodinal had or has to be lucky. No qualification was made in the quote but, yes, I have made the assumption that such a qualification was not made by Gerald as none appears in Raghu's quote attributed to Gerald

pentaxuser

 

[Alan Johnson]

I think what Gerald Koch was getting at was that with an excess of hydroxide the pH will be higher and the solution more ionized so that if there is any air admitted it will react faster. That being so, PaRodinal would not last as long as Rodinal.

 

[pentaxuser]

I think what Gerald Koch was getting at was that with an excess of hydroxide the pH will be higher and the solution more ionized so that if there is any air admitted it will react faster. That being so, PaRodinal would not last as long as Rodinal.

OK can you explain what the relevance of Gerald's quote is to PaRodinal which is what this thread is about?

Thanks

pentaxuser

 

[Alan Johnson]

Gerald said the various preparations of PaRodinal have an excess of hydroxide.
If you do the calculations this is true.
So PaRodinal will be more alkaline than Rodinal and in presence of air likely to oxidize more rapidly.