Glycin... fresh glycin... what developers to make with it?

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PhotoJim

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bnxvs said:
I can’t tell exactly the name of the supplier in Germany, as I bought glycine through a local company. Try to write to this supplier here (he had glycine in his price list): fotosuvatlar@live.de
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Careful . "Glycine" and "glycin" are two different things. Glycin is the developing agent.
 

Patrick Robert James

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As long as people keep bringing this thread back up, when I have glycin I like the Edwal developers.

Edwal 10 is the simplest. Just Glycin and Metol. The tones it gives are beautiful, and you can use it replenished so it is reasonably economical.

Edwal 12 is fantastic, but you need to add PPD which is a pain to source. Glycin/Metol/PPD. Edwal 12 will make your Tri-X look like Plus-X if that is something you are interested in.
 

DREW WILEY

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If they were spelled the same in your genetic code, no wonder so many photographers are mutants!
 

bnxvs

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PhotoJim said:
Careful . "Glycine" and "glycin" are two different things. Glycin is the developing agent.
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If you decide to correct me, correct me correctly : p-oxyphenylglycine is a developing agent. It is sometimes referred to as "photo-glycine". It has nothing to do with the drugs "glycine", "glycin", "glycine-forte" etc.
 

DREW WILEY

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I have no idea how anything is spelled in Kazakhstan. But it must have beautiful places to photograph.
 
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PhotoJim

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bnxvs said:
If you decide to correct me, correct me correctly : p-oxyphenylglycine is a developing agent. It is sometimes referred to as "photo-glycine". It has nothing to do with the drugs "glycine", "glycin", "glycine-forte" etc.
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I corrected you correctly - just not scientifically.

I've only ever seen "photo-glycine" referred to as "glycin" when referred to in reputable publications, that's all.
 
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PhotoJim

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JPD said:
And in some languages both chemicals are spelled the same.
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Very likely true. I was assuming English here. Je n'ai aucune idée comment les décrire en français.
 

JPD

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PhotoJim said:
I corrected you correctly - just not scientifically.

I've only ever seen "photo-glycine" referred to as "glycin" when referred to in reputable publications, that's all.
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PhotoJim said:
Very likely true. I was assuming English here. Je n'ai aucune idée comment les décrire en français.
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It's Glycin and Glycin in Swedish, Danish and Norwegian (Bokmål), and Glyzin - Glyzin in German (though Glycine is sometimes spelled Glycin). In Russia it's also the name of a singer, Alexey Glyzin. So if you don't make it clear when you order the chemical, you might get the amino acid or a CD. You can, of course, develop a taste for Alexey's music.
 

Michel Hardy-Vallée

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I'm starting to like the results I get from the combination of FP4+ and Agfa 72 (here with orange filter as well). The developer "respects" the natural curve of the film: with other developers I sometimes find that I get either not enough shadow detail or too much density in the highlight. Here, it's all about the midtones.
 

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Michel Hardy-Vallée

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MrclSchprs said:
Any idea what FP4's speed will be in Agfa 72?
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Empirically speaking, it was pretty close to box speed. Someone better equipped than me could measure it, but I used EI 100 to meter, and my exposure is looking good.
 

DREW WILEY

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Glycine is an amino acid, glycin is a chemical used both and in photo developers and in certain pharmaceutical and medical applications. I first purchased photo glycin from a pharmaceutical supplier. Their primary business was hospitals and the big biotech and pharmaceutical facilities all around that neighborhood - the world R&D epicenter, actually. Everyone who worked at the sales counter, as well as the owner and his wife, had phD's. Photo chemistry was a supplementary part of their business; but the glycin itself was the same. What they told me is that the only difference is that for photo usage it needs to be fresher! Likewise, if you were purchasing amidol, it was important to tell them that it was for darkroom use, because for that, it actually needed to be a higher grade than the medical version. That certainly doesn't mean either glycin or amidol were being used directly as medicines, but as ingredients in making more complex products, with all kinds of purification steps potentially involved.
 
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Raghu Kuvempunagar

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DREW WILEY said:
Likewise, if you were purchasing amidol, it was important to tell them that it was for darkroom use, because for that, it actually needed to be a higher grade than the medical version.
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If this is true then can you explain why paracetamol, the key ingredient of Amidol tablets used in medicine, has a CAS identifier which is different from that of Amidol used in developer chemistry (103-90-2 vs 95-86-3)? And why the amino acid Glycine has a different CAS identifier than the developing agent Glycin (56-40-6 vs 122-87-2)? Aren't CAS identifiers supposed to be unique?
 

DREW WILEY

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It's more involved than that. Besides, a great many biotech and pharmaceutical operations involve trade secrets, a topic way beyond this forum. In other words, it might not have anything to do with "amidol tablets". But glycine has no relation to glycin. It's the "G" in the ATGC of the DNA helix.
 

GLS

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Paracetamol and amidol are two completely different compounds, which is why they have different CAS numbers. "Amidol" is also apparently a tradename for tablets containing paracetamol, confusingly. This is why CAS numbers or systematic chemical names are best used when discussing compounds, although the latter will typically be unintelligible to any but a trained chemist.

The amino acid glycine and the compound glycin are again different molecules, hence the different CAS numbers.

DREW WILEY said:
But glycine has no relation to glycin. It's the "G" in the ATGC of the DNA helix.
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No it isn't. Glycine is an amino acid. The A, T, G and C notation of DNA refers to the "base" part of the strand monomers which, when read in triplet "codons", code for specific amino acid sequences in proteins (or as start/stop commands). The T in DNA gets replaced with U when transcoded into RNA.

A = adenine
T = thymine
G = guanine
C = cystosine
U = uracil
 
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Raghu Kuvempunagar

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GLS said:
Paracetamol and amidol are two completely different compounds, which is why they have different CAS numbers.

The amino acid glycine and the compound glycin are again different molecules, hence the different CAS numbers.
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I wonder why the PhD level staff at the pharmaceutical supplies where @DREW WILEY purchased photochemistry told him that "the glycin itself was the same" and that "the only difference is that for photo usage it needs to be fresher". Does photo glycin get converted to amino acid glycine as it ages?
 

GLS

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No, glycin does not get converted to glycine as it ages. The two compounds contain some structural similarities, but are quite different.

The people Drew mentioned were talking about the purity of the different samples/batches of glycin they had on hand. Commercial chemicals can have quite different purities or "grades" depending on supplier and method of manufacture, purification and so on. Reputable suppliers will state a certain minimum (and reliable) purity on the label, and for critical applications (such as making commercial photographic emulsions) one can buy extremely high purity examples which will come with a full certificate of analysis of trace impurities; these come at a higher cost of course. Given the choice, a purer chemical is always preferable.

Another factor with glycin specifically is that it is unstable when stored at room temperature. Not only is it prone to oxidation (as all developing agents are), but it can undergo spontaneous decarboxylation to form the free base of metol, which complicates matters. Implicit in this is that the more recently prepared a batch of glycin is, the purer it will be as it will contain less degradation products. Keeping it frozen will also help.

By the way I also have a PhD in chemistry, and it is how I make my living.
 
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DREW WILEY

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I only had three years of organic chemistry in college, and that was half a century ago, plus a Biology degree, and I've forgotten 99% of it. But my wife did recently work in Biotech, and so far, nobody has turned lead into gold, nor glycin into glycine. What I do know is that you need to buy glycin very fresh, and then keep any surplus powder tightly sealed and refrigerated, or in a freezer. I only open one 100g bottle of powder at a time. When it's new it's a yellowish off-white, then slowly shifts to tan, to light mocha brown, to dark chocolate color, and finally to almost black, as it oxidizes. The exact effect on print highlight color likewise shifts. But by the time the glycin powder turns chocolate color after six months or so, it stains everything and is essentially useless.
 

Raghu Kuvempunagar

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GLS said:
By the way I also have a PhD in chemistry, and it is how I make my living.
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I'm glad we still have experts like you to answer queries, dispel disinformation and bring clarity to discussions on matters related to photochemistry. Your participation is much appreciated.
 

GLS

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Raghu Kuvempunagar said:
I'm glad we still have experts like you to answer queries, dispel disinformation and bring clarity to discussions on matters related to photochemistry. Your participation is much appreciated.
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No problem. I will continue to provide help and advice as I can.

Organic chemistry is my particular area of expertise, which is directly relevant to much of photochemistry (although I wouldn't claim to be a photochemist). Many factors of photochemistry are still not very well understood, even today. A lot of the knowledge on this topic therefore leans on empirical observations in lieu of real understanding of what is happening at the atomic/molecular level of these "witches' brews".
 
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