Sepia Toners

[Marco B]

So, can a thiourea toner be used in the same room where I keep unexposed photo paper and sheet film? It would be nice to know once and for all.

I bought some thiourea toner with the thought that I can use it in my darkroom, instead of smelly toners that fogs my films and papers.

Yes, I use it in an enclosed bathroom darkroom with a bathroom ventilator providing the necessary exhaust ventilation. Hasn't been a problem for my stored paper there.

 

[JPD]

As long as there's reasonable ventilation, it doesn't give of fumes like Sulphide toners so there's less risks of fogging stored unexposed papers.

Yes, I use it in an enclosed bathroom darkroom with a bathroom ventilator providing the necessary exhaust ventilation. Hasn't been a problem for my stored paper there.

I'm going to try it. If I can't smell hydrogen sulphide gas, neither could the films and papers. I hope. I have a built in exhaust fan in the darkroom wall, and an air intake with a lighttrap on the opposite wall taking air from the hall.

 

[Kirk Keyes]

There should be no sulfide coming off thiourea.

Other than being "anticipated" as a human carcinogen, it should be "safe" for storage in the darkroom.

 

[naugastyle]

I use it fairly frequently as well, haven't noticed any fogging on unexposed papers. But my darkroom isn't as small as a bathroom.

 

[Marco B]

I'm going to try it. If I can't smell hydrogen sulphide gas, neither could the films and papers. I hope.

Actually, contrary to a pungent H2S smell, or ammonia from seleniumtoner, I always have the feeling my thiourea toner has a very slight not unpleasant "sweet" smell. Don't know why...

 

[pentaxuser]

I supose I should re-read the relevant section of Tim Rudman's toning book but to the best of my knowledge he was quite unequivocal that thiourea toner was perfectly safe for unexposed paper. I cannot re-call any precautions other than would apply if you were using the paper for ordinary printing, namely keep the paper in its bag and the bag in its box.

You might argue that in a papersafe the paper is less well protected from anything other than light but I don't recall any mention of any additional vulnerability in a papersafe

pentaxuser

 

[JPD]

Actually, contrary to a pungent H2S smell, or ammonia from seleniumtoner, I always have the feeling my thiourea toner has a very slight not unpleasant "sweet" smell. Don't know why...

Well, it IS related to a compound produced in the liver and excreted by the kidneys...

 

[tim rudman]

I supose I should re-read the relevant section of Tim Rudman's toning book but to the best of my knowledge he was quite unequivocal that thiourea toner was perfectly safe for unexposed paper. I cannot re-call any precautions other than would apply if you were using the paper for ordinary printing, namely keep the paper in its bag and the bag in its box.

You might argue that in a papersafe the paper is less well protected from anything other than light but I don't recall any mention of any additional vulnerability in a papersafe

pentaxuser

Sorry to come into this so late. TTBOMK there is no risk to unexposed paper when using thiourea toner. I use it a lot and am happy to use it in my darkroom and have done so for years and have never noticed any fogging of paper kept in my lightsafe drawer. It does not give off H2S.
I would not use Polysulphide or H2S emitting sepia sulphide toners in my darkroom though.
Tim

 

[RalphLambrecht]

Sorry to come into this so late. TTBOMK there is no risk to unexposed paper when using thiourea toner. I use it a lot and am happy to use it in my darkroom and have done so for years and have never noticed any fogging of paper kept in my lightsafe drawer. It does not give off H2S.
I would not use Polysulphide or H2S emitting sepia sulphide toners in my darkroom though.
Tim

Tim

Can you shed some light on the archival properties of thiourea toners? Especially of interest are any tests comparing direct and indirect toning in thiourea and (poly)sulfide.

 

[Marco B]

Tim

Can you shed some light on the archival properties of thiourea toners? Especially of interest are any tests comparing direct and indirect toning in thiourea and (poly)sulfide.

Ralph, looking at the PDF of Christopher Gmeunder that Tim Grey so kindly pointed out, and the accelerated peroxide tests therein, I see little reason for an indirect thiourea (bleach / redevelop), to be ranked less or better to a direct polysulfide toner in terms of archivability. Both provide about equal protection.

In fact, looking at the graphed data, there is just a slight warning against polysulfides at very high dilution (above 1:100, e.g. 1:200 or 1:400), since although polysulfides still work at high dilution, the test Christopher did seem to indicate that on some papers, polysulfides at high dilution seem to preferentially tone shadows, a bit like selenium, leaving the highlights a bit less protected, while it is probably the highlights that need the protection the most... No such issues though at more normal dilutions of less than, or max, 1:100. It seems recommendable to not use polysulfides at dilutions above that.

Can't speak for direct toning using thiourea, but from my one time experiment with that (simply not bleaching and using the thiourea bath at the dilution used for indirect toning), I can tell you that if it works, it is terribly slow with normal concentrations used in indirect toning, so hence maybe impractical compared a direct polysulfide toner.

 

[Marco B]

OK, I now realized I had to add one important point. The article of Christopher doesn't use a thiouread indirect toner, but a smelly sulphide based indirect toner. But my statement about thiourea is than based on the fact that both use a ferricyanide bleach first, and both convert the bleached image to Ag2S, so I am assuming here thiourea will not much differ from the Kodak sulphide indirect toner in Christophers tests, but any leads, weblinks or articles showing accelerated tests using thiourea as well, might be welcome on this thread.

 

[RalphLambrecht]

OK, I now realized I had to add one important point. The article of Christopher doesn't use a thiouread indirect toner, but a smelly sulphide based indirect toner. But my statement about thiourea is than based on the fact that both use a ferricyanide bleach first, and both convert the bleached image to Ag2S, so I am assuming here thiourea will not much differ from the Kodak sulphide indirect toner in Christophers tests, but any leads, weblinks or articles showing accelerated tests using thiourea as well, might be welcome on this thread.

Marco

I read all of that, and I did my own tests, but I was interested to find out if Tim Rudman had some test results or sources, mainly on direct thiourea toning.

 

[Vlad Soare]

I used the sodium sulfide toner a few times, probably four or five times, in the past two weeks. During all this time I had an exposed and undeveloped roll of 120 film in my darkroom, unprotected, just lying there on a shelf. The shelf was about 1.5 meters from the toner tray (my darkroom is very, very small ).
I developed that roll of film today. It looks perfect. No trace of any fog whatsoever, at least none that can be seen with the naked eye.
So, although my "test" may not be too scientific, I'm starting to think that this fogging thing might be a bit overrated. But on the other hand I have good ventilation in my darkroom. Without ventilation the results could have been different, who knows...

 

[Marco B]

It looks perfect. No trace of any fog whatsoever, at least none that can be seen with the naked eye.
So, although my "test" may not be too scientific, I'm starting to think that this fogging thing might be a bit overrated. But on the other hand I have good ventilation in my darkroom. Without ventilation the results could have been different, who knows...

I am not surprised, a one time exposure to the possible problem, good ventilation, and the film wrapped up in a roll, will probably leave little opportunity for any H2S released to do significant damage...

So yes, if you are fine like this, and don't store papers or film for ages while you tone on a regular basis, it is probably not to big an issue, also taking into accounts remarks of others concerning the limited issues with H2S smell even for the smelly sodiumsulfide (Na2S) variant of indirect sepia toners.

 

[RalphLambrecht]

I used the sodium sulfide toner a few times, probably four or five times, in the past two weeks. During all this time I had an exposed and undeveloped roll of 120 film in my darkroom, unprotected, just lying there on a shelf. The shelf was about 1.5 meters from the toner tray (my darkroom is very, very small ).
I developed that roll of film today. It looks perfect. No trace of any fog whatsoever, at least none that can be seen with the naked eye.
So, although my "test" may not be too scientific, I'm starting to think that this fogging thing might be a bit overrated. But on the other hand I have good ventilation in my darkroom. Without ventilation the results could have been different, who knows...

That's good to hear. I don't store film or paper in the darkroom. It's in a fridge in my lightroom and only brought into the darkroom for processing. That must explain why I never had a fogging problem.

 

[Marco B]

Although you always have to be careful about some judgements, read this article about ozone of a dehumidifier causing loss of optical brighteners in paper in just a few months (that are pretty useless in the long term anyway, because they will die at some point in time anyway, and optical brighteners seem to be particularly non-light fast and non-durable of all materials used in paper making):

See the image on page 8 of the article with the title described below on the Documents page of the Aardenburg Imaging & Archives centre:

Case Study #2 A Year in the Life of an Inkjet Print – Environmental, Colorimetric, and Visual Assessments

Marco

 

[RalphLambrecht]

Marco

Thanks for sharing this link. I will have to study some of the pdfs posted. You are right about the optical brighteners by the way. One can use a UV light to test that. Fresh brighteners glow under UV, old ones don't.

 

[clayne]

I have a feeling Ralph is looking for ways to bring the sulfide or other sepia toning into the darkroom.

I think that for most materials which are packaged up or protected somehow, hydrogen sulfide gas probably won't affect. However, I wouldn't do it in a room without ventilation and since ventilation is often hit and miss in the darkroom - it's natural to just do it in the kitchen or somewhere else. I usually pull prints out of the wash, polysulfide tone, stop, and then put back into the wash - so it's basically wherever I'm washing.

Actually I think most annoying parts of darkroom work aren't really related to the process - but to the jostling and shifting around of things to get work done. At least that's what annoys me the most. It gets in the way of efficiency.

I do use a dehumidifier in the darkroom, but prints are usually covered. Personally I don't depend on optical brighteners and the concept has always seemed kind of sketchy to me.

As far as archive permanence of thiourea toners, I'd also do some searches for PE's posts related to it.

 

[RalphLambrecht]

I have a feeling Ralph is looking for ways to bring the sulfide or other sepia toning into the darkroom...

Toning has never left my darkroom. Hydrogen sulfide gas is a toxin at higher concentrations and highly unpleasant with poor ventilation. Consequently, it needs proper ventilation or is better done outside. However, in the long run, poor darkroom ventilation needs to be addressed and not avoided. There are several reasons for good ventilation in the darkroom, toning is not the only one.

So, by all means, do not perform sulfide toning in the darkroom if good ventilation is a problem, but I would improve the ventilation system before I change the toning. Toning outside the darkroom is cumbersome at best (after-toning, toning stop bath, etc), and avoiding an unpleasant odor by switching to a known carcinogenic (thiourea) may not be the answer.

 

[Marco B]

Toning outside the darkroom is cumbersome at best (after-toning, toning stop bath, etc), and avoiding an unpleasant odor by switching to a known carcinogenic (thiourea) may not be the answer.

Most developers are suspected carcinogens too, so if that is really the whole picture or the main reason to avoid thiourea, I doubt it. I simply try to avoid direct contact with most photo chemicals by using the tongs for what they were designed, and wash my hands if I do accidentally get in contact with stuff.

 

[RalphLambrecht]

Most developers are suspected carcinogens too, so if that is really the whole picture or the main reason to avoid thiourea, I doubt it. I simply try to avoid direct contact with most photo chemicals by using the tongs for what they were designed, and wash my hands if I do accidentally get in contact with stuff.

I don't know about developers being carcinogens, but your post is still good advise. I don't avoid thiourea, I just don't need it. Polysulfide works well for me and has a proven track record for improving image stability, even if only light toning is preferred for aesthetic reasons.

I know that Ian Grant has started some toning efficiency tests with direct thiourea toning. I'll see what he has done and may start another comparison to see how direct thiourea toning compares to polysulfide.

 

[Marco B]

I don't know about developers being carcinogens, but your post is still good advise.

It is inconclusive, but still, hydroquinone,which is the main component of many developers, doesn't seem something to be in contact with all the time. Also note the difference between the latest 2009 datasheet, and the 2004 version.

Kodak MSDS sheets

From the Kodak MSDS datasheet of D-76 pertaining to hydroquinone

2009 sheet:
Contains: Hydroquinone. There is insufficient evidence for classifying hydroquinone as a suspected carcinogenic or mutagenic substance in humans. No increases in cancer rates were observed in an epidemiology study which looked at mortality among more than 800 persons employed primarily in the manufacture of hydroquinone. Carcinogenicity studies in animals were inconclusive. Rats and mice were given hydroquinone by stomach tube or at high concentrations in the diet. Responses were not consistent across route of exposure, species or sex. The International Agency for Research on Cancer (IARC) has classified hydroquinone in
Group 3, i.e., "not classifiable" as a carcinogen. Hydroquinone is generally negative in bacterial mutagenicity tests; there is evidence for the clastogenicity (chromosome breakage) of hydroquinone in vivo and in vitro. The relevance of chromosomal effects in test animals in
predicting human risk is unclear.

And this a bit confusing section:

Mutagenicity/Genotoxicity Data:
Salmonella typhimurium assay (Ames test): negative (in presence and absence of activation)
• Chromosomal aberration assay: negative (in absence of activation)
• Chromosomal aberration assay: positive (in presence of activation)
• Sister chromatid exchange (SCE) assay: positive (in presence and absence of activation)


2004 sheet:
Contains : Hydroquinone. In F-344 rats, chronic oral administration of
hydroquinone has resulted in the formation of benign kidney tumors thought
to be secondary to nephropathy. Hydroquinone-induced nephropathy following oral administration has been noted in the male F-344 rat, but not in other species or rat strains tested. Although an increase in mononuclear cell
leukemia in F-344 female rats has been reported following chronic oral
administration of hydroquinone, this finding was not reproduced in a subsequent study. There was no evidence of carcinogenicity in male mice
following chronic oral administration of hydroquinone; some evidence of
carcinogenic activity was shown in female mice by an increase in
hepatocellular neoplasms which were primarily benign adenomas, although
this finding was not reproduced in a subsequent study. No skin tumors were
reported in mice following long-term dermal application of hydroquinone.
Therefore, neoplastic responses have not been consistent across route of
exposure, species, or sex. Hydroquinone is generally negative in bacterial
mutagenicity tests; there is evidence for the clastogenicity (chromosome
breakage) of hydroquinone in vivo and in vitro. The relevance of the
chromosomal effects in test animals in predicting human risk is unclear.

Marco

 

[Marco B]

On the other hand, we tend to forget all those other micro or macro sources of issues, like smoking, and other sources of suspected chemicals, like plasticizers that keep plastics soft and flexible, and have a reputation of interfering or mimicking our human hormones and immune system with unknown or difficult to assess consequences...

 

[Marco B]

I don't know about developers being carcinogens, but your post is still good advise.

Toning outside the darkroom is cumbersome at best (after-toning, toning stop bath, etc), and avoiding an unpleasant odor by switching to a known carcinogenic (thiourea) may not be the answer.

I now also noticed that my thiourea based sepia toners MSDS (Material Safety Data Sheet) sheet puts thiourea in class 3 of EU directive 2001/58/EG, that is following the International Agency for Research on Cancer (IARC) classification for carcinogenicity.

For hydroquinone, according to the Kodak 2009 D-76 sheet:
The International Agency for Research on Cancer (IARC) has classified hydroquinone in Group 3, i.e., "not classifiable" as a carcinogen.

So it seems, thiourea is also ranked as "not classifiable", similar to hydroquinone...

Group 3 according to IARC:
Group 3: The agent is not classifiable as to its carcinogenicity to humans.

So both hydroquinone and thiourea, definitely are not ranking as proven human carcinogens, as that would be Group 1, nor as highly suspicious (Group 2A: probably), or possible (2B) carcinogen. Still, a bit of precaution and easy avoidance of contact by proper usage of tongs or gloves, can't hurt either.

Marco

 

[RalphLambrecht]

Marco

Thanks for the valuable clarification.
Now I'm anxious to see the test results for direct thiourea toning.