For Developer Formulators re: Guanidine Carbonate

I spoke recently with a chemist friend of mine here in Vienna who

mentioned that he had done a project some time ago using guanidine

carbonate as an accelerator in film developers in place of sodium

carbonate, etc. The chemical was a by-product of the fertilizer

manufacturer he was working for.

 

At any rate, he claimed that the effective film speed was

significantly increased and that fog was reduced to levels where the

addition of potassium bromide was not necessary.

 

I am trying to get him to e-mail me his work, but in the meantime,

have any of you ever heard of or used this chemical in photographic

applications, and if so, how?

 

TIA for your expertise and generosity.

 

Best

It's a long time since I was last in a chem lab but I've never heard of its being used in photographic chemistry. However, its structure suggests it might be a developing agent in its own right, though I can't say how active it might be.

Interesting. Hopefully Ron Mowrey will chime in. Guanidinium salts are strange beasts. The cation is a strong hydrogen-bonding group and is often used to denature proteins. I wonder if there is some interaction between the guanidinium cation and the gelatin of the emulsion.

 

The key experiment to try would be to add a near-neutral guanidine salt (guanidinium chloride would be good) to a very well-buffered developer and look at the effects (with and without guanidinium salts) at constant pH.

 

The more I think about it, the more I feel that Kodak must have tried something like this in the past. Perhaps you should ask at APUG (where the organic chemistry discussions can get more detailed).

Chris -- I don't think that guandinium salts are particularly easily oxidized. The usual reaction would be some kind of hydrolysis, followed by decarboxylation. There is an enzyme in the body that does this (to arginine, a key amino acid that has a guanidinium group on its side-chain) -- converts arginine to ornithine, a "de-guanidinylated" analogue.

Hi Doremus. Most authorities have it that only the pH of the activator or alkali counts, when it comes to the grain size produced by a developer, all other things being equal.

 

However since what we're discussing comes from Guano, there are probably plenty of minute impurities in it, dependent on the diet of the birds that originally produced it. For example, iodide salts in almost homeopathic dilutions can have a profound effect on a developer, as can compounds of ammonia.

 

I'd like to see an assay of the stuff before jumping to any conclusions, since I can't see a cheap "by-product" having any guarantee of purity, let alone being of analar quality.