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#41
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Robert Vervoordt wrote:
On Mon, 20 Sep 2004 14:42:37 -0400, Robert Vervoordt wrote: : On Mon, 20 Sep 2004 00:40:48 GMT, Donald Qualls wrote: Robert Vervoordt wrote What film have you developed with a thiocyanate-added B&W developer that had a silver AH layer? What developer did you use, and how much thiocyanate did you add? Knowing this could save me many hours of experimentation... Hmm, maybe I didn't. I can't recall any BW reversal or negative film with aSilver AH layer. I must have been thinking of using Fujicolor neg MP film in my speed boosting process that used first development in a BW formula and rehalogenation to finish in the colr development remaider of the process. You know, this brought back memories and some details. Got me thinking about it some more. When the Fujicolor negative came out of the first deveoper it showed the image and the base was a cloudy Orange color. I can't remember any Black obscuring the view through the base to the image. I know Fuji was using an internal AH layer right under the Red sensitive layer. Either this AH layer was not Silver or it was and the layer got dissolved in the developer. For a speed boost I was using Crawley's FX-11. This had a lot of solvent action, from the 125 grams of Sulfite and the inclusion of Glycin, which gets a boosted solvent action from more than a small amount of Sulfite.] Fujicolor movie or still stock? For that matter, since Fuji is relatively new to the film business, why assume they'd have a different emulsion for movie vs. still film? The AH layers in every C-41 film I'm aware of are dye based, not silver; the only silver AH I've ever heard of is in movie stock, and then it's far from universal (from what I've heard -- I have about zero experience in handling actual movie film, other than shooting one roll of cartridge 8 mm around 1981). That brought me back to something I alluded to in a previous post, in passing. Are you sure your Fomapan R has not beeen light struck or fogged? Okay, clarification he I don't have the Fomapan R yet. Try these 1. Develop an unexposed strip in D-76 in total darkness. 2. Develop in bright light. 3. Note any differences? If they are identical, it indicates either a light stuck, exposed film or severe fog. 4. Fix the film without development. 5. If it is Black, it means the AH of Fomapan R is different from others, as you described. If not then, not. We may be on a wild goose chase here. I'd actually tend to apply these in reverse order -- if fixing the film leaves it black without development, then it's silver AH, and no question about it. If it fixes clear, then I can treat it like regular negative film -- but I've already been told by J and C Photo and others who've used it that it has a silver AH layer. -- I may be a scwewy wabbit, but I'm not going to Alcatwaz! -- E. J. Fudd, 1954 Donald Qualls, aka The Silent Observer Lathe Building Pages http://silent1.home.netcom.com/HomebuiltLathe.htm Speedway 7x12 Lathe Pages http://silent1.home.netcom.com/my7x12.htm Opinions expressed are my own -- take them for what they're worth and don't expect them to be perfect. |
#42
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Robert Vervoordt wrote:
On Mon, 20 Sep 2004 14:42:37 -0400, Robert Vervoordt wrote: : On Mon, 20 Sep 2004 00:40:48 GMT, Donald Qualls wrote: Robert Vervoordt wrote What film have you developed with a thiocyanate-added B&W developer that had a silver AH layer? What developer did you use, and how much thiocyanate did you add? Knowing this could save me many hours of experimentation... Hmm, maybe I didn't. I can't recall any BW reversal or negative film with aSilver AH layer. I must have been thinking of using Fujicolor neg MP film in my speed boosting process that used first development in a BW formula and rehalogenation to finish in the colr development remaider of the process. You know, this brought back memories and some details. Got me thinking about it some more. When the Fujicolor negative came out of the first deveoper it showed the image and the base was a cloudy Orange color. I can't remember any Black obscuring the view through the base to the image. I know Fuji was using an internal AH layer right under the Red sensitive layer. Either this AH layer was not Silver or it was and the layer got dissolved in the developer. For a speed boost I was using Crawley's FX-11. This had a lot of solvent action, from the 125 grams of Sulfite and the inclusion of Glycin, which gets a boosted solvent action from more than a small amount of Sulfite.] Fujicolor movie or still stock? For that matter, since Fuji is relatively new to the film business, why assume they'd have a different emulsion for movie vs. still film? The AH layers in every C-41 film I'm aware of are dye based, not silver; the only silver AH I've ever heard of is in movie stock, and then it's far from universal (from what I've heard -- I have about zero experience in handling actual movie film, other than shooting one roll of cartridge 8 mm around 1981). That brought me back to something I alluded to in a previous post, in passing. Are you sure your Fomapan R has not beeen light struck or fogged? Okay, clarification he I don't have the Fomapan R yet. Try these 1. Develop an unexposed strip in D-76 in total darkness. 2. Develop in bright light. 3. Note any differences? If they are identical, it indicates either a light stuck, exposed film or severe fog. 4. Fix the film without development. 5. If it is Black, it means the AH of Fomapan R is different from others, as you described. If not then, not. We may be on a wild goose chase here. I'd actually tend to apply these in reverse order -- if fixing the film leaves it black without development, then it's silver AH, and no question about it. If it fixes clear, then I can treat it like regular negative film -- but I've already been told by J and C Photo and others who've used it that it has a silver AH layer. -- I may be a scwewy wabbit, but I'm not going to Alcatwaz! -- E. J. Fudd, 1954 Donald Qualls, aka The Silent Observer Lathe Building Pages http://silent1.home.netcom.com/HomebuiltLathe.htm Speedway 7x12 Lathe Pages http://silent1.home.netcom.com/my7x12.htm Opinions expressed are my own -- take them for what they're worth and don't expect them to be perfect. |
#43
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Okay, let's see if I can finish this this time without Netscape freezing
up on me (he said, after spending five hours today running Scandisk in surface scan mode)... Robert Vervoordt wrote: On Mon, 20 Sep 2004 11:23:02 GMT, Donald Qualls wrote: As you say, a quick test would show this, though I'd be tempted to try judicious overfixing first; I've acheived visible bleaching using rapid fixer with additional acetic acid added (though it took a long soak), and would expect to get results on a silver AH layer more quickly. Boy. it had better be judicious, as raoid fixers are known to begin bleaching s ilververysoonafterthetimeisextended.Thisis especially so with papers, but there have been some reports of it affecting film as well. If it works quickly enough on the Silver AH layer, that may be all you'll need. Still the addition of Thiocyanate to the developer seems more elegant, as it cuts out that extra work you described. I can't see this being any more hazardous than putting thiocyanate in the developer -- it's the same thing; if something will dissolve silver, it'll dissolve any silver. My experience suggests the fixer is very slow; it should be easy to observe and pull the film after the AH is cleared and before the image is damaged -- and I'd prefer to do it as a separate step, rather than as part of development, since that way I can change developers for one reason or another and not have to start over getting the amount of thiocyanate right. Okay, like very severe fog, then -- somwhere, if I didn't toss it when packing for my move, I have a roll of old Kodachrome II (expiry 1964) that I found in a camera and developed in Diafine; it came out solid black, but I was able to bleach in acidified rapid fixer (see above) enough to verify that there were no salvageable images on the film. I don't think that film had a silver AH layer, though. It doesn't. It has a black backing on the base surface of the film that has to be removed prior to development in an alkaline bath folloed by a wsh, at least in machine processing. This is the same black gunky stuff found in Eastmans motion picture stocks. I'm familiar with remjet, and in this case took it off with a sodium carbonate solution and gentle rubbing. The black film was what was left; I'm certain it was age fog accentuated by the Diafine. If I'd been thinking, I'd have developed in HC-110, which doesn't accentuate fog, instead of Diafine, which does. None the less, I was able to bleach down the fog to the point where I could at least see the frames and verify there was nothing of consequence in them. I think you snipped something here. I thought I pointed to Plus-X reversal being the same as Panatomic-X negative. You did -- I was just stating what I'd previously understood to be the case, from talking to others who'd (I thought) used those films for 16 mm negatives. I've seen pictures shot with Double-X Negative in 35 mm, they're much grainier than Tri-X and were shot at EI 200 -- and no, this is not Super XX from the 1950s, it was 35 mm movie stock bulk loaded into cassettes. I don't think Double-X Negative is quite the same as Tri-X. That wasn't my experience at all. I used Double-X that had a known and proper storage history, so I know that heat, radiation and age were not factors in my use. I developed both in the same developer, same tank, same time and temp and together, at once. If some of these factors were different, that might be the reason for the difference in the results you saw. Okay, if I can get some, I'll try it. The main hope here, for me, is that if it's enough like Tri-X, it might also give an EI of 1250 to 1600 in Diafine, without much more grain than development to EI 400 in D-76 or HC-110. That would be *sweet* for night shots with the Minolta 16 II. Won't be money for experimentation for a while, though; this move just keeps sucking up more and more money... Oh, I hear you! I still haven't got a place to move to. Well, with luck, we found a place (delivered a cashier's check today for the move-in, just waiting on the credit and reference checks). Hey, just spool of one roll at a time. If you don't like it, sell the remaider as a short end for movie use/ Well, I do spool one roll at at time -- only four cassettes, remember? I just hate the thought of having 198 feet of opened film that will probably bring $5 on eBay after spending $30 or so (including shipping) to get it. The shadow densities are usually made up of the largest, most resistant grains in the image; usually Iosdides. Highlights will have a greater proportion of small, slower grains. That's why Thiocyanate clears highlights and doesn't affect the rest of the image in the time normally encountered in first development. Let it sit for an hour or more and see what happens, though. Okay, then it *is* just a very slow bleach. Regardless, it sounds like its utility is solely for reversal, or for trying to get rid of a silver AH layer in processing to a negative -- and for the latter, I'd much prefer to clear the AH as a seperate operation, in the light where I can watch it (at least until I get a time for a particular concentration of thiocyanate and film). This is not at all the same as bleaching away the metallic silver of the AH layer. I wouldn't say "not at all", as what is happening in both cases is that the Thiocyanate is able to dissolve the smallest particles much sooner than it can begin to have aneffectonanythinglarger.It also works on Colloidal particles and Chlorides before it can affect the Bromides and Iododes which make up the majority of the rest of the distribution. The Chlorides ar the Halides with the least sensitivity to light. But complexing a halide to something soluble isn't at all the same kind of reaction as rendering a grain of reduced silver into a soluble compound like a sulfate -- anything that will catalyze the reaction with sulfuric acid will bleach developed silver (copper sulfate, potassium permanganate, some persulfates, etc.). Thiocyanate bleaches are usually used to rehalogenate, so the resulting halide grains can be either redeveloped or removed by conventional fixer -- aren't they? sulfite, thiosulfate, etc. are silver solvents, and their intended function (at least in that regard, since sulfite does so many other things) is generally reduction of grain by reducing halide grain size and preventing excessive growth of silver grains. Add fixing for Thiosulfate. That affects Halides long before it affects Silver. Sulfite can fix film, too, it just have very little capacity and is extremely slow. In fact, all "solvents" as the term is usually used in developing parlance, that aren't also developing agents, should be fixers (though most of them aren't strong enough to make *good* fixers). We're mincing semantics here, to some extent, but the usage of "silver solvent" to mean a halide solvent like sulfite or thiosulfate, rather than something that will redissolve or rehalogenate metallic silver, is too well established to change by fiat. Thiocyanate, IIRC, is a true bleach similar to ferricyanides, dichromates, permanganates, etc.; that is, it is capable of reacting with and dissolving or rehalogentating reduced silver. No, it's more like Thiosulfate, in that it can "fix" film. It doesn't blaech well, as it barfs on larger Halide grains and those with Iodide. But it bleaches more than thiosulfate, or we'd use it as a fixer -- thiosulfate doesn't like iodide much, either, which is why we use rapid fixer in preference to conventional fixers on modern films, especially shaped grain types; sodium thiosulfate fixers have too little capacity for complexing iodide to be reused the way we're used to doing; I suspect ammonium thiocyanate would fix as much better then sodium thiocyanate as ammonium thiosulfate outshines regular hypo. Silver is silver -- chemically, if you dissolve silver metal one place, you'll dissolve it anywhere else in the same bath, and dissolving silver *has to* cost you shadow speed in the negative. No, se info Iodides. Careful on the chemistry there -- I was talking about *silver*, the reduced metal, not silver halide. It can be confusing enough without crossing up which silver you're discussing, and I think that's most of the failure of communication we've had to this point. I'm smiling just thinking of the commotion at Foma hunting down the one guy who can answer your questions. Yeah, which is silly given that they have miles of the film around, and a warehouse full of chemicals; they should be able to simply shoot a short length and process it to verify. You expect that of marketing me? Well, no, but I do expect it of the people who ought to be answering technical questions from film consumers... In any case, if I get a roll of Fomapan R at this point it'll be an experiment, not with expectation of making good images; for images, what I really need is higher speed than I can get with Copex Rapid (which gives a nice EI 100 with the right developer), so Double X Negative looks like the right stuff. Now I just need to find my way through the maze to Kodaks Motion Picture Films outlet and get a customer number so I can order $25 worth of film -- and then find time to test it, which means it's likely to be around Christmas or later. -- I may be a scwewy wabbit, but I'm not going to Alcatwaz! -- E. J. Fudd, 1954 Donald Qualls, aka The Silent Observer Lathe Building Pages http://silent1.home.netcom.com/HomebuiltLathe.htm Speedway 7x12 Lathe Pages http://silent1.home.netcom.com/my7x12.htm Opinions expressed are my own -- take them for what they're worth and don't expect them to be perfect. |
#44
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Okay, let's see if I can finish this this time without Netscape freezing
up on me (he said, after spending five hours today running Scandisk in surface scan mode)... Robert Vervoordt wrote: On Mon, 20 Sep 2004 11:23:02 GMT, Donald Qualls wrote: As you say, a quick test would show this, though I'd be tempted to try judicious overfixing first; I've acheived visible bleaching using rapid fixer with additional acetic acid added (though it took a long soak), and would expect to get results on a silver AH layer more quickly. Boy. it had better be judicious, as raoid fixers are known to begin bleaching s ilververysoonafterthetimeisextended.Thisis especially so with papers, but there have been some reports of it affecting film as well. If it works quickly enough on the Silver AH layer, that may be all you'll need. Still the addition of Thiocyanate to the developer seems more elegant, as it cuts out that extra work you described. I can't see this being any more hazardous than putting thiocyanate in the developer -- it's the same thing; if something will dissolve silver, it'll dissolve any silver. My experience suggests the fixer is very slow; it should be easy to observe and pull the film after the AH is cleared and before the image is damaged -- and I'd prefer to do it as a separate step, rather than as part of development, since that way I can change developers for one reason or another and not have to start over getting the amount of thiocyanate right. Okay, like very severe fog, then -- somwhere, if I didn't toss it when packing for my move, I have a roll of old Kodachrome II (expiry 1964) that I found in a camera and developed in Diafine; it came out solid black, but I was able to bleach in acidified rapid fixer (see above) enough to verify that there were no salvageable images on the film. I don't think that film had a silver AH layer, though. It doesn't. It has a black backing on the base surface of the film that has to be removed prior to development in an alkaline bath folloed by a wsh, at least in machine processing. This is the same black gunky stuff found in Eastmans motion picture stocks. I'm familiar with remjet, and in this case took it off with a sodium carbonate solution and gentle rubbing. The black film was what was left; I'm certain it was age fog accentuated by the Diafine. If I'd been thinking, I'd have developed in HC-110, which doesn't accentuate fog, instead of Diafine, which does. None the less, I was able to bleach down the fog to the point where I could at least see the frames and verify there was nothing of consequence in them. I think you snipped something here. I thought I pointed to Plus-X reversal being the same as Panatomic-X negative. You did -- I was just stating what I'd previously understood to be the case, from talking to others who'd (I thought) used those films for 16 mm negatives. I've seen pictures shot with Double-X Negative in 35 mm, they're much grainier than Tri-X and were shot at EI 200 -- and no, this is not Super XX from the 1950s, it was 35 mm movie stock bulk loaded into cassettes. I don't think Double-X Negative is quite the same as Tri-X. That wasn't my experience at all. I used Double-X that had a known and proper storage history, so I know that heat, radiation and age were not factors in my use. I developed both in the same developer, same tank, same time and temp and together, at once. If some of these factors were different, that might be the reason for the difference in the results you saw. Okay, if I can get some, I'll try it. The main hope here, for me, is that if it's enough like Tri-X, it might also give an EI of 1250 to 1600 in Diafine, without much more grain than development to EI 400 in D-76 or HC-110. That would be *sweet* for night shots with the Minolta 16 II. Won't be money for experimentation for a while, though; this move just keeps sucking up more and more money... Oh, I hear you! I still haven't got a place to move to. Well, with luck, we found a place (delivered a cashier's check today for the move-in, just waiting on the credit and reference checks). Hey, just spool of one roll at a time. If you don't like it, sell the remaider as a short end for movie use/ Well, I do spool one roll at at time -- only four cassettes, remember? I just hate the thought of having 198 feet of opened film that will probably bring $5 on eBay after spending $30 or so (including shipping) to get it. The shadow densities are usually made up of the largest, most resistant grains in the image; usually Iosdides. Highlights will have a greater proportion of small, slower grains. That's why Thiocyanate clears highlights and doesn't affect the rest of the image in the time normally encountered in first development. Let it sit for an hour or more and see what happens, though. Okay, then it *is* just a very slow bleach. Regardless, it sounds like its utility is solely for reversal, or for trying to get rid of a silver AH layer in processing to a negative -- and for the latter, I'd much prefer to clear the AH as a seperate operation, in the light where I can watch it (at least until I get a time for a particular concentration of thiocyanate and film). This is not at all the same as bleaching away the metallic silver of the AH layer. I wouldn't say "not at all", as what is happening in both cases is that the Thiocyanate is able to dissolve the smallest particles much sooner than it can begin to have aneffectonanythinglarger.It also works on Colloidal particles and Chlorides before it can affect the Bromides and Iododes which make up the majority of the rest of the distribution. The Chlorides ar the Halides with the least sensitivity to light. But complexing a halide to something soluble isn't at all the same kind of reaction as rendering a grain of reduced silver into a soluble compound like a sulfate -- anything that will catalyze the reaction with sulfuric acid will bleach developed silver (copper sulfate, potassium permanganate, some persulfates, etc.). Thiocyanate bleaches are usually used to rehalogenate, so the resulting halide grains can be either redeveloped or removed by conventional fixer -- aren't they? sulfite, thiosulfate, etc. are silver solvents, and their intended function (at least in that regard, since sulfite does so many other things) is generally reduction of grain by reducing halide grain size and preventing excessive growth of silver grains. Add fixing for Thiosulfate. That affects Halides long before it affects Silver. Sulfite can fix film, too, it just have very little capacity and is extremely slow. In fact, all "solvents" as the term is usually used in developing parlance, that aren't also developing agents, should be fixers (though most of them aren't strong enough to make *good* fixers). We're mincing semantics here, to some extent, but the usage of "silver solvent" to mean a halide solvent like sulfite or thiosulfate, rather than something that will redissolve or rehalogenate metallic silver, is too well established to change by fiat. Thiocyanate, IIRC, is a true bleach similar to ferricyanides, dichromates, permanganates, etc.; that is, it is capable of reacting with and dissolving or rehalogentating reduced silver. No, it's more like Thiosulfate, in that it can "fix" film. It doesn't blaech well, as it barfs on larger Halide grains and those with Iodide. But it bleaches more than thiosulfate, or we'd use it as a fixer -- thiosulfate doesn't like iodide much, either, which is why we use rapid fixer in preference to conventional fixers on modern films, especially shaped grain types; sodium thiosulfate fixers have too little capacity for complexing iodide to be reused the way we're used to doing; I suspect ammonium thiocyanate would fix as much better then sodium thiocyanate as ammonium thiosulfate outshines regular hypo. Silver is silver -- chemically, if you dissolve silver metal one place, you'll dissolve it anywhere else in the same bath, and dissolving silver *has to* cost you shadow speed in the negative. No, se info Iodides. Careful on the chemistry there -- I was talking about *silver*, the reduced metal, not silver halide. It can be confusing enough without crossing up which silver you're discussing, and I think that's most of the failure of communication we've had to this point. I'm smiling just thinking of the commotion at Foma hunting down the one guy who can answer your questions. Yeah, which is silly given that they have miles of the film around, and a warehouse full of chemicals; they should be able to simply shoot a short length and process it to verify. You expect that of marketing me? Well, no, but I do expect it of the people who ought to be answering technical questions from film consumers... In any case, if I get a roll of Fomapan R at this point it'll be an experiment, not with expectation of making good images; for images, what I really need is higher speed than I can get with Copex Rapid (which gives a nice EI 100 with the right developer), so Double X Negative looks like the right stuff. Now I just need to find my way through the maze to Kodaks Motion Picture Films outlet and get a customer number so I can order $25 worth of film -- and then find time to test it, which means it's likely to be around Christmas or later. -- I may be a scwewy wabbit, but I'm not going to Alcatwaz! -- E. J. Fudd, 1954 Donald Qualls, aka The Silent Observer Lathe Building Pages http://silent1.home.netcom.com/HomebuiltLathe.htm Speedway 7x12 Lathe Pages http://silent1.home.netcom.com/my7x12.htm Opinions expressed are my own -- take them for what they're worth and don't expect them to be perfect. |
#45
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On Tue, 21 Sep 2004 11:13:10 GMT, Donald Qualls
wrote: Robert Vervoordt wrote: On Mon, 20 Sep 2004 14:42:37 -0400, Robert Vervoordt wrote: : On Mon, 20 Sep 2004 00:40:48 GMT, Donald Qualls wrote: Robert Vervoordt wrote What film have you developed with a thiocyanate-added B&W developer that had a silver AH layer? What developer did you use, and how much thiocyanate did you add? Knowing this could save me many hours of experimentation... Hmm, maybe I didn't. I can't recall any BW reversal or negative film with aSilver AH layer. I must have been thinking of using Fujicolor neg MP film in my speed boosting process that used first development in a BW formula and rehalogenation to finish in the colr development remaider of the process. You know, this brought back memories and some details. Got me thinking about it some more. When the Fujicolor negative came out of the first deveoper it showed the image and the base was a cloudy Orange color. I can't remember any Black obscuring the view through the base to the image. I know Fuji was using an internal AH layer right under the Red sensitive layer. Either this AH layer was not Silver or it was and the layer got dissolved in the developer. For a speed boost I was using Crawley's FX-11. This had a lot of solvent action, from the 125 grams of Sulfite and the inclusion of Glycin, which gets a boosted solvent action from more than a small amount of Sulfite.] Fujicolor movie or still stock? Fujicolor 8516 at the beginning. Fuji. in contradistinction to Eastman, used an internal AH layer. Eastman used a Remjet backing. So the Fuji may well have had a Silver AH layer; Remjet is unworkable for an internal layer, and I know of no alternatives to a Silver internal AH layer. .. For that matter, since Fuji is relatively new to the film business, why assume they'd have a different emulsion for movie vs. still film? Because the film responded just the same as Eastman color neg MP stock in all formulae. Eastman's MP stocks have some close equivalents to their still stocks, both color and BW. The major differences lie in AH layer back coating and anti static characteristics, not in the developers, to any signicant degree. Before Fuji brought out their high speed color neg for MP, I negotiated with them to obtain their 400 speed still color neg on movie spools or cores for testig and use in a project. Their final response was to smaile and urge me to wait a little bit. After getting #M to provide their 400 Daylight color neg and completing some tests, Fuji announced their 250 speed Tungsten color neg for MP use. My tests revealed a great similarity between the 3M product and the Fuji one. All were processed by Precision/DeLuxe in NYC. The lab was vey interested at first and confirmed that in this case, and with other manufacturers, the still and MP emulsions were the same basic emulsions. The AH layers in every C-41 film I'm aware of are dye based, not silver; the only silver AH I've ever heard of is in movie stock, and then it's far from universal (from what I've heard -- I have about zero experience in handling actual movie film, other than shooting one roll of cartridge 8 mm around 1981). I shot formats from R8 to 35mm in color and BW in negative and reversal. I used MP stocks in 35mm still work, even 35mm VNF reversal color newsfilm. I processed all at home. I Even, as I mentioned before, processed MP color negative in BW formulae (yes, Dialine, too) and never had an issue with the AH layers. As an added item, I processed both MP and still color neg (C-41) in divided formulae of my own construction and in Dignan's version, as well. Eventually I was souping all types together, at the same time in the same formula. They are so much alike, that this can be called a non issue. That brought me back to something I alluded to in a previous post, in passing. Are you sure your Fomapan R has not beeen light struck or fogged? Okay, clarification he I don't have the Fomapan R yet. Then how do you know that the AH layer is an issue with this film? Try these 1. Develop an unexposed strip in D-76 in total darkness. 2. Develop in bright light. 3. Note any differences? If they are identical, it indicates either a light stuck, exposed film or severe fog. 4. Fix the film without development. 5. If it is Black, it means the AH of Fomapan R is different from others, as you described. If not then, not. We may be on a wild goose chase here. I'd actually tend to apply these in reverse order -- if fixing the film leaves it black without development, then it's silver AH, and no question about it. If it fixes clear, then I can treat it like regular negative film -- but I've already been told by J and C Photo and others who've used it that it has a silver AH layer. Well, since you don't have the film to test, we'll just have to wait. For now this has all been theoretical; interesting, though, for me, in what it has enabled me to recall and pointing me to what I'll be setting up when I do get a darkroom set up after the move. Regards. Robert Vervoordt, MFA |
#46
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On Tue, 21 Sep 2004 11:13:10 GMT, Donald Qualls
wrote: Robert Vervoordt wrote: On Mon, 20 Sep 2004 14:42:37 -0400, Robert Vervoordt wrote: : On Mon, 20 Sep 2004 00:40:48 GMT, Donald Qualls wrote: Robert Vervoordt wrote What film have you developed with a thiocyanate-added B&W developer that had a silver AH layer? What developer did you use, and how much thiocyanate did you add? Knowing this could save me many hours of experimentation... Hmm, maybe I didn't. I can't recall any BW reversal or negative film with aSilver AH layer. I must have been thinking of using Fujicolor neg MP film in my speed boosting process that used first development in a BW formula and rehalogenation to finish in the colr development remaider of the process. You know, this brought back memories and some details. Got me thinking about it some more. When the Fujicolor negative came out of the first deveoper it showed the image and the base was a cloudy Orange color. I can't remember any Black obscuring the view through the base to the image. I know Fuji was using an internal AH layer right under the Red sensitive layer. Either this AH layer was not Silver or it was and the layer got dissolved in the developer. For a speed boost I was using Crawley's FX-11. This had a lot of solvent action, from the 125 grams of Sulfite and the inclusion of Glycin, which gets a boosted solvent action from more than a small amount of Sulfite.] Fujicolor movie or still stock? Fujicolor 8516 at the beginning. Fuji. in contradistinction to Eastman, used an internal AH layer. Eastman used a Remjet backing. So the Fuji may well have had a Silver AH layer; Remjet is unworkable for an internal layer, and I know of no alternatives to a Silver internal AH layer. .. For that matter, since Fuji is relatively new to the film business, why assume they'd have a different emulsion for movie vs. still film? Because the film responded just the same as Eastman color neg MP stock in all formulae. Eastman's MP stocks have some close equivalents to their still stocks, both color and BW. The major differences lie in AH layer back coating and anti static characteristics, not in the developers, to any signicant degree. Before Fuji brought out their high speed color neg for MP, I negotiated with them to obtain their 400 speed still color neg on movie spools or cores for testig and use in a project. Their final response was to smaile and urge me to wait a little bit. After getting #M to provide their 400 Daylight color neg and completing some tests, Fuji announced their 250 speed Tungsten color neg for MP use. My tests revealed a great similarity between the 3M product and the Fuji one. All were processed by Precision/DeLuxe in NYC. The lab was vey interested at first and confirmed that in this case, and with other manufacturers, the still and MP emulsions were the same basic emulsions. The AH layers in every C-41 film I'm aware of are dye based, not silver; the only silver AH I've ever heard of is in movie stock, and then it's far from universal (from what I've heard -- I have about zero experience in handling actual movie film, other than shooting one roll of cartridge 8 mm around 1981). I shot formats from R8 to 35mm in color and BW in negative and reversal. I used MP stocks in 35mm still work, even 35mm VNF reversal color newsfilm. I processed all at home. I Even, as I mentioned before, processed MP color negative in BW formulae (yes, Dialine, too) and never had an issue with the AH layers. As an added item, I processed both MP and still color neg (C-41) in divided formulae of my own construction and in Dignan's version, as well. Eventually I was souping all types together, at the same time in the same formula. They are so much alike, that this can be called a non issue. That brought me back to something I alluded to in a previous post, in passing. Are you sure your Fomapan R has not beeen light struck or fogged? Okay, clarification he I don't have the Fomapan R yet. Then how do you know that the AH layer is an issue with this film? Try these 1. Develop an unexposed strip in D-76 in total darkness. 2. Develop in bright light. 3. Note any differences? If they are identical, it indicates either a light stuck, exposed film or severe fog. 4. Fix the film without development. 5. If it is Black, it means the AH of Fomapan R is different from others, as you described. If not then, not. We may be on a wild goose chase here. I'd actually tend to apply these in reverse order -- if fixing the film leaves it black without development, then it's silver AH, and no question about it. If it fixes clear, then I can treat it like regular negative film -- but I've already been told by J and C Photo and others who've used it that it has a silver AH layer. Well, since you don't have the film to test, we'll just have to wait. For now this has all been theoretical; interesting, though, for me, in what it has enabled me to recall and pointing me to what I'll be setting up when I do get a darkroom set up after the move. Regards. Robert Vervoordt, MFA |
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On Tue, 21 Sep 2004 11:13:10 GMT, Donald Qualls
wrote: Robert Vervoordt wrote: On Mon, 20 Sep 2004 14:42:37 -0400, Robert Vervoordt wrote: : On Mon, 20 Sep 2004 00:40:48 GMT, Donald Qualls wrote: Robert Vervoordt wrote What film have you developed with a thiocyanate-added B&W developer that had a silver AH layer? What developer did you use, and how much thiocyanate did you add? Knowing this could save me many hours of experimentation... Hmm, maybe I didn't. I can't recall any BW reversal or negative film with aSilver AH layer. I must have been thinking of using Fujicolor neg MP film in my speed boosting process that used first development in a BW formula and rehalogenation to finish in the colr development remaider of the process. You know, this brought back memories and some details. Got me thinking about it some more. When the Fujicolor negative came out of the first deveoper it showed the image and the base was a cloudy Orange color. I can't remember any Black obscuring the view through the base to the image. I know Fuji was using an internal AH layer right under the Red sensitive layer. Either this AH layer was not Silver or it was and the layer got dissolved in the developer. For a speed boost I was using Crawley's FX-11. This had a lot of solvent action, from the 125 grams of Sulfite and the inclusion of Glycin, which gets a boosted solvent action from more than a small amount of Sulfite.] Fujicolor movie or still stock? Fujicolor 8516 at the beginning. Fuji. in contradistinction to Eastman, used an internal AH layer. Eastman used a Remjet backing. So the Fuji may well have had a Silver AH layer; Remjet is unworkable for an internal layer, and I know of no alternatives to a Silver internal AH layer. .. For that matter, since Fuji is relatively new to the film business, why assume they'd have a different emulsion for movie vs. still film? Because the film responded just the same as Eastman color neg MP stock in all formulae. Eastman's MP stocks have some close equivalents to their still stocks, both color and BW. The major differences lie in AH layer back coating and anti static characteristics, not in the developers, to any signicant degree. Before Fuji brought out their high speed color neg for MP, I negotiated with them to obtain their 400 speed still color neg on movie spools or cores for testig and use in a project. Their final response was to smaile and urge me to wait a little bit. After getting #M to provide their 400 Daylight color neg and completing some tests, Fuji announced their 250 speed Tungsten color neg for MP use. My tests revealed a great similarity between the 3M product and the Fuji one. All were processed by Precision/DeLuxe in NYC. The lab was vey interested at first and confirmed that in this case, and with other manufacturers, the still and MP emulsions were the same basic emulsions. The AH layers in every C-41 film I'm aware of are dye based, not silver; the only silver AH I've ever heard of is in movie stock, and then it's far from universal (from what I've heard -- I have about zero experience in handling actual movie film, other than shooting one roll of cartridge 8 mm around 1981). I shot formats from R8 to 35mm in color and BW in negative and reversal. I used MP stocks in 35mm still work, even 35mm VNF reversal color newsfilm. I processed all at home. I Even, as I mentioned before, processed MP color negative in BW formulae (yes, Dialine, too) and never had an issue with the AH layers. As an added item, I processed both MP and still color neg (C-41) in divided formulae of my own construction and in Dignan's version, as well. Eventually I was souping all types together, at the same time in the same formula. They are so much alike, that this can be called a non issue. That brought me back to something I alluded to in a previous post, in passing. Are you sure your Fomapan R has not beeen light struck or fogged? Okay, clarification he I don't have the Fomapan R yet. Then how do you know that the AH layer is an issue with this film? Try these 1. Develop an unexposed strip in D-76 in total darkness. 2. Develop in bright light. 3. Note any differences? If they are identical, it indicates either a light stuck, exposed film or severe fog. 4. Fix the film without development. 5. If it is Black, it means the AH of Fomapan R is different from others, as you described. If not then, not. We may be on a wild goose chase here. I'd actually tend to apply these in reverse order -- if fixing the film leaves it black without development, then it's silver AH, and no question about it. If it fixes clear, then I can treat it like regular negative film -- but I've already been told by J and C Photo and others who've used it that it has a silver AH layer. Well, since you don't have the film to test, we'll just have to wait. For now this has all been theoretical; interesting, though, for me, in what it has enabled me to recall and pointing me to what I'll be setting up when I do get a darkroom set up after the move. Regards. Robert Vervoordt, MFA |
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On Tue, 21 Sep 2004 21:30:13 GMT, Donald Qualls
wrote: Okay, let's see if I can finish this this time without Netscape freezing up on me (he said, after spending five hours today running Scandisk in surface scan mode)... Robert Vervoordt wrote: On Mon, 20 Sep 2004 11:23:02 GMT, Donald Qualls wrote: As you say, a quick test would show this, though I'd be tempted to try judicious overfixing first; I've acheived visible bleaching using rapid fixer with additional acetic acid added (though it took a long soak), and would expect to get results on a silver AH layer more quickly. Boy. it had better be judicious, as raoid fixers are known to begin bleaching s ilververysoonafterthetimeisextended.Thisis especially so with papers, but there have been some reports of it affecting film as well. If it works quickly enough on the Silver AH layer, that may be all you'll need. Still the addition of Thiocyanate to the developer seems more elegant, as it cuts out that extra work you described. I can't see this being any more hazardous than putting thiocyanate in the developer -- it's the same thing; if something will dissolve silver, it'll dissolve any silver. It's all about the rates at which the agents work on different forms of Silver and the amount of agent in the working solutions. While Thiocyanate is pretty effective at disslving fine, colloidal silver, it has almost no effect on deposited, large, image Silver in the small quantities used in developers. It is effective as a fixer in large quantities, approaching the 200+ grams for Thiocyanate in most fixers. You' never get near that level. My experience suggests the fixer is very slow; it should be easy to observe and pull the film after the AH is cleared and before the image is damaged -- and I'd prefer to do it as a separate step, rather than as part of development, since that way I can change developers for one reason or another and not have to start over getting the amount of thiocyanate right. Try it and let us all know wht happens. Okay, like very severe fog, then -- somwhere, if I didn't toss it when packing for my move, I have a roll of old Kodachrome II (expiry 1964) that I found in a camera and developed in Diafine; it came out solid black, but I was able to bleach in acidified rapid fixer (see above) enough to verify that there were no salvageable images on the film. I don't think that film had a silver AH layer, though. It doesn't. It has a black backing on the base surface of the film that has to be removed prior to development in an alkaline bath folloed by a wsh, at least in machine processing. This is the same black gunky stuff found in Eastmans motion picture stocks. I'm familiar with remjet, and in this case took it off with a sodium carbonate solution and gentle rubbing. The black film was what was left; I'm certain it was age fog accentuated by the Diafine. If I'd been thinking, I'd have developed in HC-110, which doesn't accentuate fog, instead of Diafine, which does. So, if I read this right, you were experimenting on outdated Kodachrome and applied the results to what you expected from Fomapan R? I don't think your concern is justified. None the less, I was able to bleach down the fog to the point where I could at least see the frames and verify there was nothing of consequence in them. Ah, so the fog was probaly not an AH Silver layer at all. It was fog in the otdated Kodachrome developed in a strong BW developer. Kodachrome has no Silver AH layer, only Remjet. I think you snipped something here. I thought I pointed to Plus-X reversal being the same as Panatomic-X negative. You did -- I was just stating what I'd previously understood to be the case, from talking to others who'd (I thought) used those films for 16 mm negatives. Just making sure we are on the same page. I've seen pictures shot with Double-X Negative in 35 mm, they're much grainier than Tri-X and were shot at EI 200 -- and no, this is not Super XX from the 1950s, it was 35 mm movie stock bulk loaded into cassettes. I don't think Double-X Negative is quite the same as Tri-X. That wasn't my experience at all. I used Double-X that had a known and proper storage history, so I know that heat, radiation and age were not factors in my use. I developed both in the same developer, same tank, same time and temp and together, at once. If some of these factors were different, that might be the reason for the difference in the results you saw. Okay, if I can get some, I'll try it. The main hope here, for me, is that if it's enough like Tri-X, it might also give an EI of 1250 to 1600 in Diafine, without much more grain than development to EI 400 in D-76 or HC-110. That would be *sweet* for night shots with the Minolta 16 II. It did for me. Hope there isn't some subtle glitch that makes it grainier in 16mm, as sharness is one of the prime considerations for MP stocks. I never saw a problem with my use in 35mm for XX or the GAF Gevaert, Ferrania and other Eastman stocks I got my hands on. stocks and Won't be money for experimentation for a while, though; this move just keeps sucking up more and more money... Oh, I hear you! I still haven't got a place to move to. Well, with luck, we found a place (delivered a cashier's check today for the move-in, just waiting on the credit and reference checks). I just put in an offer on one today too. Synchronicity? Hey, just spool of one roll at a time. If you don't like it, sell the remaider as a short end for movie use/ Well, I do spool one roll at at time -- only four cassettes, remember? I just hate the thought of having 198 feet of opened film that will probably bring $5 on eBay after spending $30 or so (including shipping) to get it. Cost of experimentation. Is it deductible? The shadow densities are usually made up of the largest, most resistant grains in the image; usually Iosdides. Highlights will have a greater proportion of small, slower grains. That's why Thiocyanate clears highlights and doesn't affect the rest of the image in the time normally encountered in first development. Let it sit for an hour or more and see what happens, though. Okay, then it *is* just a very slow bleach. Regardless, it sounds like its utility is solely for reversal, or for trying to get rid of a silver AH layer in processing to a negative -- and for the latter, I'd much prefer to clear the AH as a seperate operation, in the light where I can watch it (at least until I get a time for a particular concentration of thiocyanate and film). Sounds like a plan to me. This is not at all the same as bleaching away the metallic silver of the AH layer. I wouldn't say "not at all", as what is happening in both cases is that the Thiocyanate is able to dissolve the smallest particles much sooner than it can begin to have aneffectonanythinglarger.It also works on Colloidal particles and Chlorides before it can affect the Bromides and Iododes which make up the majority of the rest of the distribution. The Chlorides ar the Halides with the least sensitivity to light. But complexing a halide to something soluble isn't at all the same kind of reaction as rendering a grain of reduced silver into a soluble compound like a sulfate -- anything that will catalyze the reaction with sulfuric acid will bleach developed silver (copper sulfate, potassium permanganate, some persulfates, etc.). Thiocyanate bleaches are usually used to rehalogenate, so the resulting halide grains can be either redeveloped or removed by conventional fixer -- aren't they? I haven't run across anything like that. I used some of the others you mentioned, mostly Copper, but never found anything about using Thiocyanate for a rehalogenation application. Can you cite this? sulfite, thiosulfate, etc. are silver solvents, and their intended function (at least in that regard, since sulfite does so many other things) is generally reduction of grain by reducing halide grain size and preventing excessive growth of silver grains. Add fixing for Thiosulfate. That affects Halides long before it affects Silver. Sulfite can fix film, too, it just have very little capacity and is extremely slow. You can say that again; no, don't. In fact, all "solvents" as the term is usually used in developing parlance, that aren't also developing agents, should be fixers (though most of them aren't strong enough to make *good* fixers). Thiocyanate, while used for fixing in the past, fell out of use due to its relative cost and its different action on fine silver. We're mincing semantics here, to some extent, but the usage of "silver solvent" to mean a halide solvent like sulfite or thiosulfate, rather than something that will redissolve or rehalogenate metallic silver, is too well established to change by fiat. I think that's straightened out now. Thiocyanate, IIRC, is a true bleach similar to ferricyanides, dichromates, permanganates, etc.; that is, it is capable of reacting with and dissolving or rehalogentating reduced silver. No, it's more like Thiosulfate, in that it can "fix" film. It doesn't blaech well, as it barfs on larger Halide grains and those with Iodide. But it bleaches more than thiosulfate, or we'd use it as a fixer -- thiosulfate doesn't like iodide much, either, which is why we use rapid fixer in preference to conventional fixers on modern films, especially shaped grain types; sodium thiosulfate fixers have too little capacity for complexing iodide to be reused the way we're used to doing; I suspect ammonium thiocyanate would fix as much better then sodium thiocyanate as ammonium thiosulfate outshines regular hypo. Perhaps, but I see no real interest in pursuing that thread. Silver is silver -- chemically, if you dissolve silver metal one place, you'll dissolve it anywhere else in the same bath, and dissolving silver *has to* cost you shadow speed in the negative. No, se info Iodides. Careful on the chemistry there -- I was talking about *silver*, the reduced metal, not silver halide. It can be confusing enough without crossing up which silver you're discussing, and I think that's most of the failure of communication we've had to this point. Silver metal is found in an emulsion in different forms. Ther is the larger, reduced Silver that forms an image and th efiner forms, deposited Silver, as a result of using a high solvent developer, and the colloidal Silver that is used to form an internal AH layer. This is where the differnces between Thiosulfat, Sulfit and Thiocyanate come into play. I'm smiling just thinking of the commotion at Foma hunting down the one guy who can answer your questions. Yeah, which is silly given that they have miles of the film around, and a warehouse full of chemicals; they should be able to simply shoot a short length and process it to verify. You expect that of marketing me? Well, no, but I do expect it of the people who ought to be answering technical questions from film consumers... In any case, if I get a roll of Fomapan R at this point it'll be an experiment, not with expectation of making good images; for images, what I really need is higher speed than I can get with Copex Rapid (which gives a nice EI 100 with the right developer), so Double X Negative looks like the right stuff. Now I just need to find my way through the maze to Kodaks Motion Picture Films outlet and get a customer number so I can order $25 worth of film -- and then find time to test it, which means it's likely to be around Christmas or later. Happy Holidays. Robert Vervoordt, MFA |
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On Tue, 21 Sep 2004 21:30:13 GMT, Donald Qualls
wrote: Okay, let's see if I can finish this this time without Netscape freezing up on me (he said, after spending five hours today running Scandisk in surface scan mode)... Robert Vervoordt wrote: On Mon, 20 Sep 2004 11:23:02 GMT, Donald Qualls wrote: As you say, a quick test would show this, though I'd be tempted to try judicious overfixing first; I've acheived visible bleaching using rapid fixer with additional acetic acid added (though it took a long soak), and would expect to get results on a silver AH layer more quickly. Boy. it had better be judicious, as raoid fixers are known to begin bleaching s ilververysoonafterthetimeisextended.Thisis especially so with papers, but there have been some reports of it affecting film as well. If it works quickly enough on the Silver AH layer, that may be all you'll need. Still the addition of Thiocyanate to the developer seems more elegant, as it cuts out that extra work you described. I can't see this being any more hazardous than putting thiocyanate in the developer -- it's the same thing; if something will dissolve silver, it'll dissolve any silver. It's all about the rates at which the agents work on different forms of Silver and the amount of agent in the working solutions. While Thiocyanate is pretty effective at disslving fine, colloidal silver, it has almost no effect on deposited, large, image Silver in the small quantities used in developers. It is effective as a fixer in large quantities, approaching the 200+ grams for Thiocyanate in most fixers. You' never get near that level. My experience suggests the fixer is very slow; it should be easy to observe and pull the film after the AH is cleared and before the image is damaged -- and I'd prefer to do it as a separate step, rather than as part of development, since that way I can change developers for one reason or another and not have to start over getting the amount of thiocyanate right. Try it and let us all know wht happens. Okay, like very severe fog, then -- somwhere, if I didn't toss it when packing for my move, I have a roll of old Kodachrome II (expiry 1964) that I found in a camera and developed in Diafine; it came out solid black, but I was able to bleach in acidified rapid fixer (see above) enough to verify that there were no salvageable images on the film. I don't think that film had a silver AH layer, though. It doesn't. It has a black backing on the base surface of the film that has to be removed prior to development in an alkaline bath folloed by a wsh, at least in machine processing. This is the same black gunky stuff found in Eastmans motion picture stocks. I'm familiar with remjet, and in this case took it off with a sodium carbonate solution and gentle rubbing. The black film was what was left; I'm certain it was age fog accentuated by the Diafine. If I'd been thinking, I'd have developed in HC-110, which doesn't accentuate fog, instead of Diafine, which does. So, if I read this right, you were experimenting on outdated Kodachrome and applied the results to what you expected from Fomapan R? I don't think your concern is justified. None the less, I was able to bleach down the fog to the point where I could at least see the frames and verify there was nothing of consequence in them. Ah, so the fog was probaly not an AH Silver layer at all. It was fog in the otdated Kodachrome developed in a strong BW developer. Kodachrome has no Silver AH layer, only Remjet. I think you snipped something here. I thought I pointed to Plus-X reversal being the same as Panatomic-X negative. You did -- I was just stating what I'd previously understood to be the case, from talking to others who'd (I thought) used those films for 16 mm negatives. Just making sure we are on the same page. I've seen pictures shot with Double-X Negative in 35 mm, they're much grainier than Tri-X and were shot at EI 200 -- and no, this is not Super XX from the 1950s, it was 35 mm movie stock bulk loaded into cassettes. I don't think Double-X Negative is quite the same as Tri-X. That wasn't my experience at all. I used Double-X that had a known and proper storage history, so I know that heat, radiation and age were not factors in my use. I developed both in the same developer, same tank, same time and temp and together, at once. If some of these factors were different, that might be the reason for the difference in the results you saw. Okay, if I can get some, I'll try it. The main hope here, for me, is that if it's enough like Tri-X, it might also give an EI of 1250 to 1600 in Diafine, without much more grain than development to EI 400 in D-76 or HC-110. That would be *sweet* for night shots with the Minolta 16 II. It did for me. Hope there isn't some subtle glitch that makes it grainier in 16mm, as sharness is one of the prime considerations for MP stocks. I never saw a problem with my use in 35mm for XX or the GAF Gevaert, Ferrania and other Eastman stocks I got my hands on. stocks and Won't be money for experimentation for a while, though; this move just keeps sucking up more and more money... Oh, I hear you! I still haven't got a place to move to. Well, with luck, we found a place (delivered a cashier's check today for the move-in, just waiting on the credit and reference checks). I just put in an offer on one today too. Synchronicity? Hey, just spool of one roll at a time. If you don't like it, sell the remaider as a short end for movie use/ Well, I do spool one roll at at time -- only four cassettes, remember? I just hate the thought of having 198 feet of opened film that will probably bring $5 on eBay after spending $30 or so (including shipping) to get it. Cost of experimentation. Is it deductible? The shadow densities are usually made up of the largest, most resistant grains in the image; usually Iosdides. Highlights will have a greater proportion of small, slower grains. That's why Thiocyanate clears highlights and doesn't affect the rest of the image in the time normally encountered in first development. Let it sit for an hour or more and see what happens, though. Okay, then it *is* just a very slow bleach. Regardless, it sounds like its utility is solely for reversal, or for trying to get rid of a silver AH layer in processing to a negative -- and for the latter, I'd much prefer to clear the AH as a seperate operation, in the light where I can watch it (at least until I get a time for a particular concentration of thiocyanate and film). Sounds like a plan to me. This is not at all the same as bleaching away the metallic silver of the AH layer. I wouldn't say "not at all", as what is happening in both cases is that the Thiocyanate is able to dissolve the smallest particles much sooner than it can begin to have aneffectonanythinglarger.It also works on Colloidal particles and Chlorides before it can affect the Bromides and Iododes which make up the majority of the rest of the distribution. The Chlorides ar the Halides with the least sensitivity to light. But complexing a halide to something soluble isn't at all the same kind of reaction as rendering a grain of reduced silver into a soluble compound like a sulfate -- anything that will catalyze the reaction with sulfuric acid will bleach developed silver (copper sulfate, potassium permanganate, some persulfates, etc.). Thiocyanate bleaches are usually used to rehalogenate, so the resulting halide grains can be either redeveloped or removed by conventional fixer -- aren't they? I haven't run across anything like that. I used some of the others you mentioned, mostly Copper, but never found anything about using Thiocyanate for a rehalogenation application. Can you cite this? sulfite, thiosulfate, etc. are silver solvents, and their intended function (at least in that regard, since sulfite does so many other things) is generally reduction of grain by reducing halide grain size and preventing excessive growth of silver grains. Add fixing for Thiosulfate. That affects Halides long before it affects Silver. Sulfite can fix film, too, it just have very little capacity and is extremely slow. You can say that again; no, don't. In fact, all "solvents" as the term is usually used in developing parlance, that aren't also developing agents, should be fixers (though most of them aren't strong enough to make *good* fixers). Thiocyanate, while used for fixing in the past, fell out of use due to its relative cost and its different action on fine silver. We're mincing semantics here, to some extent, but the usage of "silver solvent" to mean a halide solvent like sulfite or thiosulfate, rather than something that will redissolve or rehalogenate metallic silver, is too well established to change by fiat. I think that's straightened out now. Thiocyanate, IIRC, is a true bleach similar to ferricyanides, dichromates, permanganates, etc.; that is, it is capable of reacting with and dissolving or rehalogentating reduced silver. No, it's more like Thiosulfate, in that it can "fix" film. It doesn't blaech well, as it barfs on larger Halide grains and those with Iodide. But it bleaches more than thiosulfate, or we'd use it as a fixer -- thiosulfate doesn't like iodide much, either, which is why we use rapid fixer in preference to conventional fixers on modern films, especially shaped grain types; sodium thiosulfate fixers have too little capacity for complexing iodide to be reused the way we're used to doing; I suspect ammonium thiocyanate would fix as much better then sodium thiocyanate as ammonium thiosulfate outshines regular hypo. Perhaps, but I see no real interest in pursuing that thread. Silver is silver -- chemically, if you dissolve silver metal one place, you'll dissolve it anywhere else in the same bath, and dissolving silver *has to* cost you shadow speed in the negative. No, se info Iodides. Careful on the chemistry there -- I was talking about *silver*, the reduced metal, not silver halide. It can be confusing enough without crossing up which silver you're discussing, and I think that's most of the failure of communication we've had to this point. Silver metal is found in an emulsion in different forms. Ther is the larger, reduced Silver that forms an image and th efiner forms, deposited Silver, as a result of using a high solvent developer, and the colloidal Silver that is used to form an internal AH layer. This is where the differnces between Thiosulfat, Sulfit and Thiocyanate come into play. I'm smiling just thinking of the commotion at Foma hunting down the one guy who can answer your questions. Yeah, which is silly given that they have miles of the film around, and a warehouse full of chemicals; they should be able to simply shoot a short length and process it to verify. You expect that of marketing me? Well, no, but I do expect it of the people who ought to be answering technical questions from film consumers... In any case, if I get a roll of Fomapan R at this point it'll be an experiment, not with expectation of making good images; for images, what I really need is higher speed than I can get with Copex Rapid (which gives a nice EI 100 with the right developer), so Double X Negative looks like the right stuff. Now I just need to find my way through the maze to Kodaks Motion Picture Films outlet and get a customer number so I can order $25 worth of film -- and then find time to test it, which means it's likely to be around Christmas or later. Happy Holidays. Robert Vervoordt, MFA |
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On Tue, 21 Sep 2004 21:30:13 GMT, Donald Qualls
wrote: Okay, let's see if I can finish this this time without Netscape freezing up on me (he said, after spending five hours today running Scandisk in surface scan mode)... Robert Vervoordt wrote: On Mon, 20 Sep 2004 11:23:02 GMT, Donald Qualls wrote: As you say, a quick test would show this, though I'd be tempted to try judicious overfixing first; I've acheived visible bleaching using rapid fixer with additional acetic acid added (though it took a long soak), and would expect to get results on a silver AH layer more quickly. Boy. it had better be judicious, as raoid fixers are known to begin bleaching s ilververysoonafterthetimeisextended.Thisis especially so with papers, but there have been some reports of it affecting film as well. If it works quickly enough on the Silver AH layer, that may be all you'll need. Still the addition of Thiocyanate to the developer seems more elegant, as it cuts out that extra work you described. I can't see this being any more hazardous than putting thiocyanate in the developer -- it's the same thing; if something will dissolve silver, it'll dissolve any silver. It's all about the rates at which the agents work on different forms of Silver and the amount of agent in the working solutions. While Thiocyanate is pretty effective at disslving fine, colloidal silver, it has almost no effect on deposited, large, image Silver in the small quantities used in developers. It is effective as a fixer in large quantities, approaching the 200+ grams for Thiocyanate in most fixers. You' never get near that level. My experience suggests the fixer is very slow; it should be easy to observe and pull the film after the AH is cleared and before the image is damaged -- and I'd prefer to do it as a separate step, rather than as part of development, since that way I can change developers for one reason or another and not have to start over getting the amount of thiocyanate right. Try it and let us all know wht happens. Okay, like very severe fog, then -- somwhere, if I didn't toss it when packing for my move, I have a roll of old Kodachrome II (expiry 1964) that I found in a camera and developed in Diafine; it came out solid black, but I was able to bleach in acidified rapid fixer (see above) enough to verify that there were no salvageable images on the film. I don't think that film had a silver AH layer, though. It doesn't. It has a black backing on the base surface of the film that has to be removed prior to development in an alkaline bath folloed by a wsh, at least in machine processing. This is the same black gunky stuff found in Eastmans motion picture stocks. I'm familiar with remjet, and in this case took it off with a sodium carbonate solution and gentle rubbing. The black film was what was left; I'm certain it was age fog accentuated by the Diafine. If I'd been thinking, I'd have developed in HC-110, which doesn't accentuate fog, instead of Diafine, which does. So, if I read this right, you were experimenting on outdated Kodachrome and applied the results to what you expected from Fomapan R? I don't think your concern is justified. None the less, I was able to bleach down the fog to the point where I could at least see the frames and verify there was nothing of consequence in them. Ah, so the fog was probaly not an AH Silver layer at all. It was fog in the otdated Kodachrome developed in a strong BW developer. Kodachrome has no Silver AH layer, only Remjet. I think you snipped something here. I thought I pointed to Plus-X reversal being the same as Panatomic-X negative. You did -- I was just stating what I'd previously understood to be the case, from talking to others who'd (I thought) used those films for 16 mm negatives. Just making sure we are on the same page. I've seen pictures shot with Double-X Negative in 35 mm, they're much grainier than Tri-X and were shot at EI 200 -- and no, this is not Super XX from the 1950s, it was 35 mm movie stock bulk loaded into cassettes. I don't think Double-X Negative is quite the same as Tri-X. That wasn't my experience at all. I used Double-X that had a known and proper storage history, so I know that heat, radiation and age were not factors in my use. I developed both in the same developer, same tank, same time and temp and together, at once. If some of these factors were different, that might be the reason for the difference in the results you saw. Okay, if I can get some, I'll try it. The main hope here, for me, is that if it's enough like Tri-X, it might also give an EI of 1250 to 1600 in Diafine, without much more grain than development to EI 400 in D-76 or HC-110. That would be *sweet* for night shots with the Minolta 16 II. It did for me. Hope there isn't some subtle glitch that makes it grainier in 16mm, as sharness is one of the prime considerations for MP stocks. I never saw a problem with my use in 35mm for XX or the GAF Gevaert, Ferrania and other Eastman stocks I got my hands on. stocks and Won't be money for experimentation for a while, though; this move just keeps sucking up more and more money... Oh, I hear you! I still haven't got a place to move to. Well, with luck, we found a place (delivered a cashier's check today for the move-in, just waiting on the credit and reference checks). I just put in an offer on one today too. Synchronicity? Hey, just spool of one roll at a time. If you don't like it, sell the remaider as a short end for movie use/ Well, I do spool one roll at at time -- only four cassettes, remember? I just hate the thought of having 198 feet of opened film that will probably bring $5 on eBay after spending $30 or so (including shipping) to get it. Cost of experimentation. Is it deductible? The shadow densities are usually made up of the largest, most resistant grains in the image; usually Iosdides. Highlights will have a greater proportion of small, slower grains. That's why Thiocyanate clears highlights and doesn't affect the rest of the image in the time normally encountered in first development. Let it sit for an hour or more and see what happens, though. Okay, then it *is* just a very slow bleach. Regardless, it sounds like its utility is solely for reversal, or for trying to get rid of a silver AH layer in processing to a negative -- and for the latter, I'd much prefer to clear the AH as a seperate operation, in the light where I can watch it (at least until I get a time for a particular concentration of thiocyanate and film). Sounds like a plan to me. This is not at all the same as bleaching away the metallic silver of the AH layer. I wouldn't say "not at all", as what is happening in both cases is that the Thiocyanate is able to dissolve the smallest particles much sooner than it can begin to have aneffectonanythinglarger.It also works on Colloidal particles and Chlorides before it can affect the Bromides and Iododes which make up the majority of the rest of the distribution. The Chlorides ar the Halides with the least sensitivity to light. But complexing a halide to something soluble isn't at all the same kind of reaction as rendering a grain of reduced silver into a soluble compound like a sulfate -- anything that will catalyze the reaction with sulfuric acid will bleach developed silver (copper sulfate, potassium permanganate, some persulfates, etc.). Thiocyanate bleaches are usually used to rehalogenate, so the resulting halide grains can be either redeveloped or removed by conventional fixer -- aren't they? I haven't run across anything like that. I used some of the others you mentioned, mostly Copper, but never found anything about using Thiocyanate for a rehalogenation application. Can you cite this? sulfite, thiosulfate, etc. are silver solvents, and their intended function (at least in that regard, since sulfite does so many other things) is generally reduction of grain by reducing halide grain size and preventing excessive growth of silver grains. Add fixing for Thiosulfate. That affects Halides long before it affects Silver. Sulfite can fix film, too, it just have very little capacity and is extremely slow. You can say that again; no, don't. In fact, all "solvents" as the term is usually used in developing parlance, that aren't also developing agents, should be fixers (though most of them aren't strong enough to make *good* fixers). Thiocyanate, while used for fixing in the past, fell out of use due to its relative cost and its different action on fine silver. We're mincing semantics here, to some extent, but the usage of "silver solvent" to mean a halide solvent like sulfite or thiosulfate, rather than something that will redissolve or rehalogenate metallic silver, is too well established to change by fiat. I think that's straightened out now. Thiocyanate, IIRC, is a true bleach similar to ferricyanides, dichromates, permanganates, etc.; that is, it is capable of reacting with and dissolving or rehalogentating reduced silver. No, it's more like Thiosulfate, in that it can "fix" film. It doesn't blaech well, as it barfs on larger Halide grains and those with Iodide. But it bleaches more than thiosulfate, or we'd use it as a fixer -- thiosulfate doesn't like iodide much, either, which is why we use rapid fixer in preference to conventional fixers on modern films, especially shaped grain types; sodium thiosulfate fixers have too little capacity for complexing iodide to be reused the way we're used to doing; I suspect ammonium thiocyanate would fix as much better then sodium thiocyanate as ammonium thiosulfate outshines regular hypo. Perhaps, but I see no real interest in pursuing that thread. Silver is silver -- chemically, if you dissolve silver metal one place, you'll dissolve it anywhere else in the same bath, and dissolving silver *has to* cost you shadow speed in the negative. No, se info Iodides. Careful on the chemistry there -- I was talking about *silver*, the reduced metal, not silver halide. It can be confusing enough without crossing up which silver you're discussing, and I think that's most of the failure of communication we've had to this point. Silver metal is found in an emulsion in different forms. Ther is the larger, reduced Silver that forms an image and th efiner forms, deposited Silver, as a result of using a high solvent developer, and the colloidal Silver that is used to form an internal AH layer. This is where the differnces between Thiosulfat, Sulfit and Thiocyanate come into play. I'm smiling just thinking of the commotion at Foma hunting down the one guy who can answer your questions. Yeah, which is silly given that they have miles of the film around, and a warehouse full of chemicals; they should be able to simply shoot a short length and process it to verify. You expect that of marketing me? Well, no, but I do expect it of the people who ought to be answering technical questions from film consumers... In any case, if I get a roll of Fomapan R at this point it'll be an experiment, not with expectation of making good images; for images, what I really need is higher speed than I can get with Copex Rapid (which gives a nice EI 100 with the right developer), so Double X Negative looks like the right stuff. Now I just need to find my way through the maze to Kodaks Motion Picture Films outlet and get a customer number so I can order $25 worth of film -- and then find time to test it, which means it's likely to be around Christmas or later. Happy Holidays. Robert Vervoordt, MFA |
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