What Makes Amidol Go Bad?

In 2005, (there was a url link here which no longer exists) asked in (there was a url link here which no longer exists), a little downthread:
He didn't receive much of an answer.

I'd like to renew his question in 2015 (almost '16).

What is the chemical explanation for the extremely short life of Amidol paper developer?

Is it the oxidation with atmospheric oxygen of the Amidol molecule alone dissolved in water?

Is it the oxidation with atmospheric oxygen of Amidol in combination with the other ingredients in the formula dissolved in water?

Is it the decomposition of the Amidol molecule when dissolved in water, even in the absence of dissolved oxygen in H20 and at the air interface?

Or is it an unstoppable train of interactions between the various ingredients together in solution, and/or when they come in contact with the silver halides in the emulsion?

Thanks!

Of the three developer, stop bath and hypo, developer is the most sensitive to oxidation. I have lost other developers overnight in the tray, some but not all.

Personally, I've never tried to keep a tray of developer overnight, but I have done 4 - 5 hour printing sessions with Amidol and it's performance was the same beginning to end. Perhaps, the type of Amidol used is/was an issue; if you don't know, there's a Chinese version and an English version. Chinese Amidol didn't work out for me, but the English variety is wonderful. Perhaps, the water used to mix the developer is/was an issue; I use either distilled water or filtered/reverse osmosis water.

So, I guess if you're calling <24 hours "extremely short life of Amidol paper developer", then, maybe, for you it's not the best choice. LPD, maybe?

I don't know the answer, but I have neen able to use Michael A. Smith's amidol versions, both the Azo version and the enlarging paper version, over a two day weekend. Perhaps the ingredients other than amidol do have an impact on tray life.
Juan

So, I guess if you're calling <24 hours "extremely short life of Amidol paper developer", then, maybe, for you it's not the best choice.

Click to expand...

I'm asking more because I'm genuinely curious as to the chemical explanation for why Amidol has a short lifespan compared to other developers like Dektol and LPD.

So far, I haven't found it, though it might be out there. I'm sure it's out there. It's just a matter of whether it is locked up in an engineer or very experienced photographer's mind or written down. Maybe if it is in someone's mind they might be generous enough to share!

With that knowledge, I think it might be possible to make an Amidol formulation that has superior keeping properties, or, packaged differently to not go bad.

I mix my Amidol with English from TPF and distilled water, but I don't like the time and hazards involved with mixing straight from individual powders every time. No fume hood, only a flexible duct attached to a 360 CFPM fan-rather like a vacuum that is great at dislodging expensive powders from my weighing scoop. I've only printed with it once or twice.

When I searched earlier threads I saw that some people mix a large batch of all the ingredients in powder form. This sounds good but I think it would be difficult to mix a truly homogeneous "master" powder and then ratio out to one-shot pouches, b/c of different weights of ingredients. Does it work just fine this way?

Still would love an explanation! thank you.

Edit: I should add that, no, the short keeping time of Amidol isn't a good fit for me, because I'm a busy working professional. Very rarely can I get a good 4 hour stretch of time to print. That includes weekends. 2 hours is what I can put aside. Weighing out chems cuts into that time, and it's much more efficient time-wise to mix up chemicals beforehand and use the same solution again and again, as with dektol, than to mix from scratch every time.But I reaaaaaaally want to experiment with Amidol because I've heard legend as to what it can do, and want to test whether that is legend or truth.

It will help to understand that Amidol itself is a reducing agent, not a developer. Dektol is a developer with 2 reducing agents, metol and hydroqionone. This doesn't answer your question but its the first step

Nikonic said:

I'm asking more because I'm genuinely curious as to the chemical explanation for why Amidol has a short lifespan compared to other developers like Dektol and LPD.

Click to expand...

The formula published by MAS shows an acid Amidol solution is best for development. Amidiol is a very powerful reducing agent and goes bad in solution very quickly.

Developer: Amidol for use with Azo. Mix at room temperature just before use.

One liter
Water-------------900 cc
Sodium Sulfite----- 30 g
Citric Acid--------- 3 g
KBr (10% solution)-- 2 cc
Amidol--------------8 g
Water to make final amount. Develop for no more than one minute.

I've tracked stability of this for up to 1 day and watched it deteriorate, and I used 2 batches of Amidol. One was the old old original batch and the other was the new Chinese batch. Both were black masses that looked DOA, but did work as described.

I have been able to doctor the developer formula above, and come up with several others that will last for a few days to a week or so, but they are not very good IMHO for the purpose they were intended. They do develop well, but still don't keep well.

PE

I've tracked stability of this for up to 1 day and watched it deteriorate

Click to expand...

PE, is the deterioration caused by exposure to atmospheric oxygen? Or Amidol as a reducing molecule deteriorating as a result of interactions with the other ingredients in the developer?

Thanks

Oxygen is the culprit here. There are no oxidants in the formula above.

However, polymerization in the presence of oxygen and acid (or base) are possible routes to self destruction.

Sorry, I've not studied it, just observed it and tried to work around it.

PE

Photo Engineer said:

Oxygen is the culprit here. There are no oxidants in the formula above.

However, polymerization in the presence of oxygen and acid (or base) are possible routes to self destruction.

Sorry, I've not studied it, just observed it and tried to work around it.

PE

Click to expand...

Very good. Thank you for sharing what you know.

Amidol is the only developing agent that will develop in acid solution. Decades ago when it was popular several weak acids were used to acidify the solution if it was desired to extend its life. The acid addition does however slow down the developer's action.

Is the photo grade solid amidol the free base or HCl salt? If the salt, I might have hoped it would be sold nearly colorless in well sealed glass bottles.

either way in solution it's going to have a pronounced tendency to make highly colored oxidation products.

Do do any of you purge developer bottles (dry chemicals or solutions, stock or working) with dry nitrogen or (better) Argon? I kind of doubt it would be worth the expense, but I've never tried to pencil it out. I used to be a chemist and worked with far more oxygen sensitive compounds with fairly simple precautions like rubber septa, syringes, and a slight over pressure of dry oxygen free Argon. it is a little hard to imagine how that could be translated to tray development though. Perhaps a trickle of argon into a covered tray?

When I hypothesized:

I think it might be possible to make an Amidol formulation that has superior keeping properties, or, packaged differently to not go bad.

Click to expand...

I meant something along these lines, especially purging with inert gas.

Fr. Mark said:

Do do any of you purge developer bottles (dry chemicals or solutions, stock or working) with dry nitrogen or (better) Argon? I kind of doubt it would be worth the expense, but I've never tried to pencil it out.

Click to expand...

I'll be experimenting.

"Worth the expense" for me means more than just money, but time and convenience as well.

With developing agents like Amidol and Glycin it is best to only purchase amounts that can be used in a reasonable time. Yes, it's a bit more expensive but so is discarding spoiled chemicals.

Nikonic said:

I mix my Amidol with English from TPF and distilled water, but I don't like the time and hazards involved with mixing straight from individual powders every time. No fume hood, only a flexible duct attached to a 360 CFPM fan-rather like a vacuum that is great at dislodging expensive powders from my weighing scoop. I've only printed with it once or twice.

Click to expand...

First, AFAIK the Amidol from TPF is the Chinese variety. The only source for English Amidol that I'm aware of is ArtCraft Chemicals; there may be others. If you use the Chinese variety, it must be filtered often during a printing session. And, based on non-scientific experience it doesn't last as long as English in the tray.

FWIW, I use the MAS formula and mix all ingredients, sans the Amidol, ahead of time; kind of a "stock" solution. Then, when I'm ready to print I mix in the Amidol, outside with a respirator, gloves, etc, then bring mixed solution into darkroom and away I go. Maybe this might help you with the time involved?

Kind regards,
Alan

Alan9940 said:

The only source for English Amidol that I'm aware of is ArtCraft Chemicals;

FWIW, I use the MAS formula and mix all ingredients, sans the Amidol, ahead of time; kind of a "stock" solution. Then, when I'm ready to print I mix in the Amidol, outside with a respirator, gloves, etc, then bring mixed solution into darkroom and away I go. Maybe this might help you with the time involved?

Kind regards,
Alan

Click to expand...

Yes! I bought from Artcraft for the Amidol. I just remember the "finest English Amidol" in the description and for some reason thought that was something TPF would write as product copy. I buy from so many different places (and lately, eBay) I lose track.

I would love to go outside, but I live in New York City. I'd give it about 2-3 minutes of standing on the sidewalk with a respirator and a table of chemicals before being tackled by the NYPD and dragged away into one of the dark caves they keep for interrogating terrorist attempts/suspects, and spending months or years there before being released.

Nikonic said:

I would love to go outside, but I live in New York City. I'd give it about 2-3 minutes of standing on the sidewalk with a respirator and a table of chemicals before being tackled by the NYPD and dragged away into one of the dark caves they keep for interrogating terrorist attempts/suspects, and spending months or years there before being released.

Click to expand...

Are you "cooking", sir? oliceman:

You're probably right about that!!

Alan9940 said:

Are you "cooking", sir? oliceman:

You're probably right about that!!

Click to expand...

Aha!

For the record though, I do order all of my chemicals lawfully, and use them for lawful purposes: exclusively chemical photography.

As to my quip, it really was no joke. New York City takes counterterrorism very, very seriously, and (controversy aside) they handcuff first and ask questions later. http://nymag.com/nymetro/news/features/n_8286/

I am a citizen who lawfully uses non-hazardous chemicals for benign and lawful purposes. I even ensure that nothing goes down the drain that should not.