Hi,I've just tried out the DS-12 film developer formula by Ryuji Suzuki at http://silvergrain.org/Photo-Tech/film-dev-recommend.html . It seems hydrogen sulfide was formed at two stages and I'd like to know why. I've got a clue, but I just want confirmation and some assessment of the risks if you can. For reference, the formula goes:
metol 0,4 gascorbic acid 1,0 gsodium sulfite 20 gsalicylic acid 0,2 gtriethanolamine 2 mlsodium carbonate 2,0 g and water to 1 litre. What I made was three litres of developer starting with about 0,2 litres initial dissolving volume, just tap water. Of course it didn't all go into the initial 0,2 litres, so it was more like immersed for sodium sulfite. So three times the amounts above in three litres (if any of this counts). The thing I did wrong was to dissolve metol only after ascorbic acid, because this was my first time with the home scale and fume cupboard so I thought it would be safer to check the scale this way. I think I got the rotten egg smell, which I now take was hydrogen sulfide, after I added metol to the mix.
Since I did this in a fume cupboard there was little smell, but it smelled outside the house when I left the room, so maybe there was much more blown out in the exhaust. The second time the smell appeared was in the toiler-for-a-darkroom when I dipped my gloved hands in the same washing bucket after immersing them in both the developer and the fixer (Ilford Hypam).I just checked the metol I was provided with and realised that it's of the p-Methylaminophenol sulfate-variety. Is the variety referred to in the formula supposed to be plain metol? I'm a bit poor at chemistry, but the way I see it, sodium sulfite's there to provide alkalinity, but can it be said that the sulphur in sodium sulfite is more stable than the one in the metol I got? It's bound to three oxygens instead of the four in the metol. Would this mean there's little or no risk of hetting hydrogen sulfide with the DS-12 formula as such if the metol's sulphur free? I'd say this is the case, but I'm no chemist and I don't know how marked the difference im the sulphur compound stabilities is here and how much hydrogen sulfide I might get? I read that the nose is highly sensitive for H2S, but then again nose does adapt, the toxic amounts are very low and I don't have room to faint anywhere but ON the chemicals.The CAS number for the metol I got is 55-55-0, whereas plain metol has the number 150-75-4 (searched ChemId). The MSDS I got for the 55-55-0 -stuff has "information not available" in the stability/reactivity field, but the English version found on www.acros.com (the provider) says about hazardous decomposition products : Oxides of sulfur, sodium oxide and not compatible with acids. To return to my main question: Does the DS-12 normally generate hydrogen sulfide when combined with acids? Sorry for lack of coherence above, but if I really had a very specific idea, I wouldn't have to ask. Cheers! Antti