View Full Version : Does Amidol keep in water?

Eric Woodbury
12-Apr-2010, 13:50
I'd like to mix Amidol in water with a little ascorbic acid and have it ready on the shelf. How long will this keep? Is there an optimum ratio or is everything okay as long as the solution is acid?

Thanks in advance.

Brook Martin
12-Apr-2010, 16:33
The working solutions are generally acidic and oxidize quickly, so I doubt it. It mixes so fast and easy there is really not much advantage if it did work. It lasts very long as powder.

Jay DeFehr
12-Apr-2010, 16:49

As you know, amidol is active in a slightly acid environment, so amidol and ascorbic acid might make a working developer without any sulfite or other alkali. Ascorbic acid and amidol are both known for their poor keeping qualities in aqueous solutions, so I'm not optimistic about the keeping properties of a mixture of the two, but maybe someone will suggest an effective preservative. I think Ryuji Suzuki uses salycilic acid to preserve his ascorbate developers; maybe it would work for amidol/ascorbate too? Good luck!

Eric Woodbury
12-Apr-2010, 21:10
I hadn't thought of salycilic acid. I have some. I'll try that. I read somewhere about lactic acid and amidol, too.

Robert Hughes
13-Apr-2010, 07:16
Reminds me of the old Bill Cosby routine, "The Chicken Heart"...

In a radio mystery theater voice:

"The Chicken Heart was kept in a laboratory vat,
Half Blood, half Sodium salicylate.
One day a janitor carelessly knocked the vat over (oops).
He went to get a rag to clean it up (whistles).
The Chicken Heart grew -
Six Feet, Eight Inches Tall -
And in Search
Of Human Blood!"

Drew Wiley
13-Apr-2010, 12:10
I use a little citric acid, along with sodium sulfite and benzotriazole. These can be mixed together in advance. But the amidol is always added just before the print session, never the day before.

Michael A. Smith
13-Apr-2010, 15:50
Amidol does not keep pre-mixed. Mix it only before use. Since Amidol mixes up quickly at room temperature there is no advantage at all in pre-mixing it. No time will be saved.

Michael A. Smith

Jay DeFehr
13-Apr-2010, 16:15
One of many possible advantages to making a stable stock solution is limiting one's exposure to airborne particles of toxic chemicals, inevitable when mixing powders. Other possible advantages include measuring very small quantities from percent solutions instead of weighing out dry chemicals directly.

Drew Wiley
14-Apr-2010, 10:00
Jay - amidol is a slightly clumpy powder which doesn't seem to easily drift around in the air. Second, mixing very small quantities of it is dicey due to the susceptibility of
this chemical to batch variation and humidity absorbtion. It's a finicky and powerful
developer, and tricky to use for repeatable film development, for example. With the
quantities of amidol used in a typical printing session, however, I find it both predictable and cost effective. I keep the powder very dry and do not store it in the
sink room at all. I weigh out what I need for the working solution and cap this into a
dry empty 35mm film canister, then add to this powder to the other premixed ingredients just before use. The citric acid prolongs its tray life for several hours at least, but certainly not overnite. Very very easy to use.

Eric Woodbury
14-Apr-2010, 10:21
Jay, thanks for the tips. Since I'm using small amounts, I've been dissolving it in PG to make reliable measurement possible and quick, but I was hoping to eliminate the PG. From the responses here, that doesn't seem possible. The other advantage to not having the powder around is that it turns everything black. I see why it is a hair dye.

Brook Martin
14-Apr-2010, 11:38
I have a cheap (+/- $25.00) grain scale made for reloaders that is good for tiny measurements like this. I do wet plate, so turning everything black is a forgone conclusion.

Eric Woodbury
14-Apr-2010, 12:00
Brook, thanks. I use the same scale. It is fine, but tedious. I prefer measuring larger amounts so that I can use my triple beam. And on those days when I'm mindless, measure one liquid is even better.

I have a grey plastic sink that was grey for 25 years. After a couple rounds of using Amidol, it started turning dark. Very odd. I also had some white towels that I wiped up the slightest amounts of spilled powder. Now they are definitely makred as darkroom towels.

Brook Martin
14-Apr-2010, 13:39
I use to have a darkroom in the back of a flower shop. One day a traveling salesman came by with some stuff that he said could take the stain off of anything. I went and got a tray stained w/ amidol and told him if his stuff could get the stain off the tray I would buy a bottle, if it didnt he had to give me a bottle. I got a free bottle of pretty good cleaning stuff. At least cyanide gets silver out, I dont know of anything that gets amidol out once dry.

Drew Wiley
14-Apr-2010, 16:27
Every "real" photographer has black dev trays. It's like a badge or medal or certificate
of authenticity. Black fingernails I can do without. I use gloves.