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#41
November 2nd 04, 07:21 PM
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Dieter Zakas wrote:
in article , Donald Qualls at wrote on 11/1/04 18:02: Y'know, we still need to find a fixer in the grocery store -- we've got a couple different developers (Caffenol, and more recently one made from acetaminophen), and stop bath, but no fixer... MacGyver, where are you when we need you? :-) No, not him -- he can't managed to develop film in coffee and use the orange juice as stop bath, with the result that his film turns black while he's looking at it (though I found it interesting that it was cleared, as if fixed, rather than milky as unfixed film should be); instead, he used the OJ as developer (and what did he alkalize either one with, we don't know) and pulled the film into the light without even a stop bath. Sad to say, though there have been dozens of fixers over the past 170 or so years, only the thiosulfates have ever gone anywhere. Salt water or sea water has been said to fix, but it doesn't. Sodium sulfite does, but has very low capacity and is extremely slow even in saturated solution -- as in, soak your film for days and change solution several times trying for a good fix. Most of the other potential fixers are also fogging agents (not that big a deal, as long as you avoid developer carry over) or bleaches (very bad, if you're losing image while you remove the undeveloped halide), or both. Even thiosulfate can bleach, weakly, in an acidic solution. No, sodium thiosulfate isn't particularly toxic -- it's the specific antidote for prussic acid, aka cyanide, though it has to be administered almost instantly (another strike against MacGyver -- by the time he got Pete Thornton the fixer from the mini-lab, which should have contained toxic levels of dissolved silver, it was too late to save a real cyanide victim, even if he wasn't quite dead yet). The problem with fixers is only partly that the halogens grip metal ions very tightly; fixing requires both a chemical that can solubilize silver ions, *and* one that can keep the halogen ions from reforming insoluble halides with the silver. Chloride, Bromide, and Iodide will all replace nitrate -- not because they're more reactive than the nitrate ion, but because their compound is insoluble, so any tiny bit that forms immediately drops out of the reaction as an insoluble solid. The thiosulfates provide sodium or ammonium ions to keep the chloride happy and in solution while the thiosulfate complexes the silver in a form that doesn't just re-react with the chloride in solution -- and that trick is one tha few chemicals can manage. The places to look would be in the thio- family, because of the affinity between silver and sulfur, but most of them are also fogging agents -- thiourea, for instance (these days called carbamide), and thiocyanates, are both strong foggants. There may be other thio- chemicals, however, that could complex silver and resolubilize it from a halide crystal -- perhaps a thionitrate or thiophosphate, if such things aren't just the fevered dreams of a non-chemist. None of those, however, are likely to appear on grocery aisles as common household materials. Hmm. Maybe garlic juice, with its high concentration of allyl sulfide? It's probably a foggant, but might it be a fixer? And if so, could any of us stand to use it immediately after half an hour in the same room with Caffenol? -- The challenge to the photographer is to command the medium, to use whatever current equipment and technology furthers his creative objectives, without sacrificing the ability to make his own decisions. -- Ansel Adams Donald Qualls, aka The Silent Observer http://silent1.home.netcom.com Opinions expressed are my own -- take them for what they're worth and don't expect them to be perfect. 
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#42
November 2nd 04, 07:21 PM
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Dieter Zakas wrote:
in article , Donald Qualls at wrote on 11/1/04 18:02: Y'know, we still need to find a fixer in the grocery store -- we've got a couple different developers (Caffenol, and more recently one made from acetaminophen), and stop bath, but no fixer... MacGyver, where are you when we need you? :-) No, not him -- he can't managed to develop film in coffee and use the orange juice as stop bath, with the result that his film turns black while he's looking at it (though I found it interesting that it was cleared, as if fixed, rather than milky as unfixed film should be); instead, he used the OJ as developer (and what did he alkalize either one with, we don't know) and pulled the film into the light without even a stop bath. Sad to say, though there have been dozens of fixers over the past 170 or so years, only the thiosulfates have ever gone anywhere. Salt water or sea water has been said to fix, but it doesn't. Sodium sulfite does, but has very low capacity and is extremely slow even in saturated solution -- as in, soak your film for days and change solution several times trying for a good fix. Most of the other potential fixers are also fogging agents (not that big a deal, as long as you avoid developer carry over) or bleaches (very bad, if you're losing image while you remove the undeveloped halide), or both. Even thiosulfate can bleach, weakly, in an acidic solution. No, sodium thiosulfate isn't particularly toxic -- it's the specific antidote for prussic acid, aka cyanide, though it has to be administered almost instantly (another strike against MacGyver -- by the time he got Pete Thornton the fixer from the mini-lab, which should have contained toxic levels of dissolved silver, it was too late to save a real cyanide victim, even if he wasn't quite dead yet). The problem with fixers is only partly that the halogens grip metal ions very tightly; fixing requires both a chemical that can solubilize silver ions, *and* one that can keep the halogen ions from reforming insoluble halides with the silver. Chloride, Bromide, and Iodide will all replace nitrate -- not because they're more reactive than the nitrate ion, but because their compound is insoluble, so any tiny bit that forms immediately drops out of the reaction as an insoluble solid. The thiosulfates provide sodium or ammonium ions to keep the chloride happy and in solution while the thiosulfate complexes the silver in a form that doesn't just re-react with the chloride in solution -- and that trick is one tha few chemicals can manage. The places to look would be in the thio- family, because of the affinity between silver and sulfur, but most of them are also fogging agents -- thiourea, for instance (these days called carbamide), and thiocyanates, are both strong foggants. There may be other thio- chemicals, however, that could complex silver and resolubilize it from a halide crystal -- perhaps a thionitrate or thiophosphate, if such things aren't just the fevered dreams of a non-chemist. None of those, however, are likely to appear on grocery aisles as common household materials. Hmm. Maybe garlic juice, with its high concentration of allyl sulfide? It's probably a foggant, but might it be a fixer? And if so, could any of us stand to use it immediately after half an hour in the same room with Caffenol? -- The challenge to the photographer is to command the medium, to use whatever current equipment and technology furthers his creative objectives, without sacrificing the ability to make his own decisions. -- Ansel Adams Donald Qualls, aka The Silent Observer http://silent1.home.netcom.com Opinions expressed are my own -- take them for what they're worth and don't expect them to be perfect.
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#43
November 2nd 04, 07:26 PM
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Nicholas O. Lindan wrote:
Donald Qualls at wrote Still, if you're paying to ship glacial acetic (ground only, hazmat surcharge, and in winter you have to wonder if it will freeze in transit) You buy it locally: $8-$10 / gal. from a chemicals supplier, usually 5 gal minimum. Also available from graphic arts and some industrial supply firms. - or - $25-$30 / gal. from a photo store It is expected to freeze: melting point is 62F. Yep, but can you buy bromocresol yellow locally, too? Or will you have to pay $12 to ship your $8 gram of indicator dye? And besides that, your five gallon minimum of glacial is at least $40 -- dilute 1:32 to get 3% working stop bath solution, and you have 160 gallons of stop bath (and yes, of course you don't dilute it all at once, but then you have to store the moderately hazardous glacial acid, or dilute it all to more than fifteen gallons of 28% stock). So, for somewhere between fifty and seventy dollars, you can save on stop bath -- or you can spend $1.50 for a gallon of white vinegar, dilute 1:1, and one shot it for a nickel per roll of film. I don't think I can afford to save that much. -- The challenge to the photographer is to command the medium, to use whatever current equipment and technology furthers his creative objectives, without sacrificing the ability to make his own decisions. -- Ansel Adams Donald Qualls, aka The Silent Observer http://silent1.home.netcom.com Opinions expressed are my own -- take them for what they're worth and don't expect them to be perfect.
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#44
November 3rd 04, 04:53 PM
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On 30 Oct 2004 11:54:34 -0700,
(Laura Halliday) wrote: .... I use water stop bath on film, BTW. I tried an acid stop and found the film sometimes reacted badly. So I stopped. Paper seems to need the acid stop, though... .... nov304 from Lloyd Erlick, I've found FB paper is perfectly simple to do with no acid at all in the process. The non-acid approach has several advantages for me. The disadvantages are easily overcome. My pontifications on this subject are available under the 'technical' heading in the table of contents on www.heylloyd.com regards, --le ________________________________ Lloyd Erlick Portraits, Toronto. voice: 416-686-0326 email: net: www.heylloyd.com ________________________________
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#46
November 3rd 04, 04:55 PM
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sorry for double post ...
--le ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =---
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