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Photo Forum / Film Photography / Darkroom / April 2005Safety with chemicals
I have bought "Historic Photographic Processes" by Richard Farber. Reading some parts of it I noticed that in every sensitizing process is involved one or more dangerous chemicals. Now I ask myself about the real danger they rappresent. There are a lot of exclamation marks beside the dangerous ingriedents, but also beside special operation that require attention to not spoilt results and that have nothing to do with safety. There are also, about Bichromat Gum warning about Pigments, telling that some of this could be even cancerogenic. There are generations of painters that have prepaired by themselves colours and they all have lived a very long time. Talbot live a long time too, and it doesn't like it has been killed by silver salts. Fixers sold on every store makes air unbreathable, and none consider them dangerous, even if they look like when you smell at them. I would like to know if someone of you has experience with this operations and what can tell me about the real dangers of them. Thanks. > I have bought "Historic Photographic Processes" by Richard > Farber. Reading some parts of it I noticed that in every sensitizing [quoted text clipped - 11 lines] > like to know if someone of you has experience with this operations and > what can tell me about the real dangers of them. Thanks. You might read Chapter 4, Safety In The Darkroom in Richard J. Henry's book, "Controls in Black and White Photography" Second Edition. Another worthwhile book is M. Alice Ottoboni's "The Dose makes the Poison -- A Plain-Language Guide to Toxicology" Second Edition.  Signature.~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 07:50:00 up 5 days, 1:05, 3 users, load average: 3.33, 3.26, 3.18 >> I have bought "Historic Photographic Processes" by Richard >> Farber. Reading some parts of it I noticed that in every sensitizing [quoted text clipped - 16 lines] >book is M. Alice Ottoboni's "The Dose makes the Poison -- A Plain-Language >Guide to Toxicology" Second Edition. Could you tell me mora about it? I don't live in England and is not really simple for me to find those books. If you could summarize some of the contents you would help me. Thanks >>> I have bought "Historic Photographic Processes" by Richard >>>Farber. Reading some parts of it I noticed that in every sensitizing [quoted text clipped - 20 lines] > really simple for me to find those books. If you could summarize some > of the contents you would help me. Thanks I do not live in England either. It is really difficult to teach a course in toxicology in only a few words in an Internet posting even were I a professional toxicologist, which I am not. Here is my attempt. USE A LITTLE COMMON SENSE! Now there is nothing so rare as common sense, so I hope you are one of the elect who have it. Dr. Henry was an MD who did mainly work in research chemistry. He advocated not taking an hysterical approach to black and white darkroom safety. M. Alice Ottoboni, Ph.D., was Staff Toxicologist with the California State Department of Public Health for over twenty years. Her book is not a course in toxicology, but it explains the subject in a way that an educated member of the general public can understand. To do that limited task required her 244 pages. It is already a summary. For me to attempt to summarize her summary in a few sentences would do it an injustice. If you care, you will just have to do a little work, perhaps at a good public or university library. I hope your country has libraries and universities. Signature.~. Jean-David Beyer Registered Linux User 85642. /V\ PGP-Key: 9A2FC99A Registered Machine 241939. /( )\ Shrewsbury, New Jersey http://counter.li.org ^^-^^ 08:50:00 up 5 days, 2:05, 4 users, load average: 3.45, 3.36, 3.32 ... >Fixers sold on every store makes air unbreathable, and none consider >them dangerous, even if they look like when you smell at them. ... apr1505 from Lloyd Erlick, There is absolutely no need to tolerate such materials in the darkroom. In particular, fixer that bites the nose is unnecessary. I have written articles on these matters, available on my website. Look under the 'technical' button in the table of contents. regards, --le Signature________________________________ Lloyd Erlick Portraits, Toronto. voice: 416-686-0326 email: portrait@heylloyd.com net: www.heylloyd.com ________________________________ >... >>Fixers sold on every store makes air unbreathable, and none consider [quoted text clipped - 5 lines] >There is absolutely no need to tolerate such materials in the >darkroom. In particular, fixer that bites the nose is unnecessary. Right, when I can I use sodium thiosulfate that doesn't smell, but the problem is with conservation. I have read that you can't put it in the bottle after using it, because it will not work the day after. This is the problem, because now I am trying pinhole photography and I need to see the result to understund what kind of exposure times are the best for the camera I have made (times on schedule are not always right), and to do it everyday, I need to conservate chemicals from day to day. I would be possible to make a sodium thiosulfate fixer and to add a component to conserve it, but a component that doesn't smell? > Right, when I can I use sodium thiosulfate that doesn't smell, but the > problem is with conservation. I have read that you can't put it in the > bottle after using it, because it will not work the day after. This is TF-2 doesn't smell. Well maybe if you pour it up your nose-) http://www.jackspcs.com/tf2.htm Keeps very well. Nick > TF-2 doesn't smell. Well maybe if you pour it up your nose-) > > http://www.jackspcs.com/tf2.htm > > Keeps very well. Does anybody have experience with Arista Premium Powder (Odorless) Fixer, or know what it's equivalent to? http://www.freestylephoto.biz/sc_prod.php?cat_id=303&pid=595 According to the MSDS sheet (available from http://www.freestylephoto.biz/t_msds_arista.php), it's got sodium thiosulfate (like the formula to which you referred), sodium acetate, and sodium metabisulfite. FWIW, I'm interested because I feel like I've got a slightly sore throat and a slightly runny nose for a day or so after an enlarging session, so I'm looking for chemicals that are somewhat less irritating, and the Arista is the least expensive "odorless" fixer I've seen advertised. (I'm currently using Dektol, Kodak indicator stop bath, and Kodak fixer.) I might eventually get into mixing my own stuff, like TF-2, from scratch, but I'm not quite ready to explore that area. Advice on other developers and/or stop baths is also appreciated, or if anybody can suggest which of the chemicals is likely to be causing my mild reaction, I can focus on that one. Thanks. SignatureRod Smith, rodsmith@rodsbooks.com http://www.rodsbooks.com Author of books on Linux, FreeBSD, and networking >... >FWIW, I'm interested because I feel like I've got a slightly sore throat >and a slightly runny nose for a day or so after an enlarging session ... apr1605 from Lloyd Erlick, This is a good example of why I went on a smell abatement rampage in my darkroom a few years ago. There is absolutely no reason to tolerate any such irritation. In high school I had a chemistry teacher who had grown tired of teenagers. His attitude had become scornful and snide to the extreme. He inadvertently told us the reason we should not use fixers that bite our noses ... The gas coming out of these fixers is sulfur dioxide. Sulfur dioxide dissolves readily in water, and our mucous membranes contain plenty of water. If we inhale sulfur dioxide, it dissolves in the water in our mucous membranes, which are located in our noses, bronchia and lungs, and reacts with the water to form sulfurous acid. These locations contain plenty of oxygen, and sulfurous acid oxidizes readily to form sulfuric acid. This is why it bites your nose, and I have been unable to include the appropriate level of snideness; it's a tone of voice, I guess. A fixer that contains no acid will not emit sulfur dioxide. It's very easy and cheap to make fixer from raw materials. I have an article about it on my website, under the 'technical' heading' in the table of contents. regards, --le Signature________________________________ Lloyd Erlick Portraits, Toronto. voice: 416-686-0326 email: portrait@heylloyd.com net: www.heylloyd.com ________________________________ >>... >>>Fixers sold on every store makes air unbreathable, and none consider [quoted text clipped - 15 lines] >I would be possible to make a sodium thiosulfate fixer and to add a >component to conserve it, but a component that doesn't smell? apr1605 from Lloyd Erlick, It is very easy to make a sodium thiosulfate fixer that has absolutely no smell. Ansel Adams published a fixer formula in the Appendix of "The Print" for a fixer he called 'plain fixer'. It consists of 160 grams anhydrous sodium thiosulfate and about twenty grams of anhydrous sodium sulfite per liter. It stores as well as any other fixer, and it has a relatively low capacity so there should be no need to store for long periods. It is very cheap and easy to prepare. I go on a greater length in one of the articles on my website. (In case I have not been descriptive enough, sodium sulfite is an ingredient often called an 'oxygen scavenger'. It reacts with oxygen very readily, more so than sodium thiosulfate, and therefore protects the thiosulfate from oxidation in a fixer solution. The protection will last for many days or even weeks, hopefully long enough for the worker to use up the capacity of the fixer.) regards, --le Signature________________________________ Lloyd Erlick Portraits, Toronto. voice: 416-686-0326 email: portrait@heylloyd.com net: www.heylloyd.com ________________________________ >>On Sat, 16 Apr 2005 08:55:12 -0400, Lloyd Erlick <Lloyd at >>@the-wire. [quoted text clipped - 71 lines] > net: www.heylloyd.com > ________________________________ The sulfite in fixing baths serves a couple of purposes. In the usual acid fixing bath it is necessary to prevent the acid from decomposing the thiosulfate. In a neutral fixing bath much less sulfite is necessary and there is no generation of sulfur dioxide gas because of the lack of acid. Acid fixing baths typically have about 15 grams/liter of sulfite. A non-acid bath needs no more than about 5 grams/liter although a bit more will help prevent staining from carried over developer. The acid in fixing baths is necessary for the hardener. If the hardener is left out the fixing bath does not need to be acid although the acid has the advantage of prevent carried over developer from continuing to be active in the fixer. A fixer made with either sodium or ammonium thiosulfate (rapid fixer) and sulfite is quite satisfactory provided a sufficient rinse between developer and fixing bath is used. A "plain water" stop bath must be more than just a dip in water, it should be a short wash to remove as much developer from the emulsion as possible. The use of a non hardening fixing bath will result in greater washing efficiency, a neutral fixing bath in even better washing efficiency. However, the use of a sulfite wash aid such as Kodak Hypo Clearing Agent will result in even faster washing when used with any fixer. Signature--- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com > > apr1505 from Lloyd Erlick, > > [quoted text clipped - 6 lines] > that you can't put it in the bottle after using it, > because it will not work the day after. UNADULTERATED S. or A. thiosulfate will do the job. Neither gives forth any fumes or oder, solid, concentrate, or working strength. Preservatives and ph modifiers, which are not needed, are added to all off the shelf fixers. I use fixer, S. or A., VERY DILUTE, one-shot; use once then toss. Place enough of the solid or concentrate in the needed amount of solution. Do a few tests. S. or A. Thio, I keep a few small bottles on hand. When needed I add one to make up the solution volume needed. Doing as I do you will always have fresh fixer and know that it will fully do the job. Use off the shelf fixers the same way, VERY DILUTE, one shot. Oder and fumes will be at a minimum. Dan > There is absolutely no need to tolerate ... fixer > that bites the nose... Some, on the other tong, love the smell of fixer in the morning. In either case, the parfume of fixer is not, AFAAK, harmful. SignatureNicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. To reply, remove spaces: n o lindan at ix . netcom . com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ >> There is absolutely no need to tolerate ... fixer >> that bites the nose... [quoted text clipped - 4 lines] >In either case, the parfume of fixer is not, AFAAK, >harmful. apr1705 from Lloyd Erlick, The perfume of fixer is quite different from the bite. Plain fix has a very pleasant, distinctive, gentle scent due to sodium thiosulfate. One must be around it for a while, or lean over and look for it, to smell it. Like a good perfume! To me, this is the scent of the darkroom, the smell of photography (along with the smell of a roll of film and the smell of a newly opened package of paper). The bite of sulfur dioxide is not the smell of fixer in the morning, at least not to me. regards, --le Signature________________________________ Lloyd Erlick Portraits, Toronto. voice: 416-686-0326 email: portrait@heylloyd.com net: www.heylloyd.com ________________________________ > I have bought "Historic Photographic Processes" by Richard > Farber. Reading some parts of it I noticed that in every [quoted text clipped - 24 lines] > operations and > what can tell me about the real dangers of them. Thanks. There are some chemicals used in photography, especially some alternative processes, that must be handled with care and with some knowledge of basic chemical safety. Processes like Gum Bichromate, Carbon, and others use Potassium bichromate to sensitize the coating. This material can cause severe burns so the powder and concentrated solutions should be kept off the skin. Some chromium compounds are carcinogenic (valence 6 but not valence 3). In general substances like bichromate should be handled with protection by means of nitrile gloves, an apron, a face mask, and good ventillation. Most chemicals used in conventional B&W photography are not dangerous in the amounts and forms used. Prepared or packaged chemistry is not particularly hazardous but the use of gloves and a face mask (for powders) are good precautions. Fixing baths can emmit sulfur dioxide gas. This has a sharp odor. It can set off asthma in those sensitive to it. A non-acid fixing bath will eliminate the odor since it comes from a reaction between the acid and other ingredients. The acid is needed only if a hardener is used. Some are sentive to the odor of Acetic acid, used in stop baths and some fixing baths. If a non-acid fixer is used an acid stop bath can not be used, rather a plain water short wash takes its place. If a conventional fixer is used there are a number of alternatives to Acetic acid. Citric acid is odor free. It is not quite compatible with alum hardener but is perfectly satisfactory for a non hardening acid fixing bath. Ilford's packaged stop bath is citric acid. There are other alternatives. Silver nitrate is hazardous but is not used in many conventional B&W darkroom processes. It is used mainly in emulsion making and in some toners. It is difficult to find reliable information on chemical safety. Some of the more popular books, especially those intended for artists, are written by people with questionable qualifications in toxicology and are full of errors and exagerations. _The Dose Makes the Poison_ by M. Alice Ottoboni, as recommended by J-P Beyer in another post is a good place to start. MSDS can be misleading because they are _legal_ not scientific or technical documents, meant mostly to protect the manufacturer from legal jeapordy, and often discuss the problems of massive storage or use of the substances they cover. Signature--- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com |
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