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Capacity/life of rapid fixer
On Sun, 04 Apr 2010 03:29:41 -0700, sreenath wrote:
Hi, I am using a rapid fixer sold in India be the name "Agefix" The instructions that come with the bottle just suggests a dilution of 3-5 times for film. I have been using the suggested dilution with no problem. My question is the capacity of this diluted fixer. I kept using the 1 liter for more than a year. Every time I do a film clip test and observe that film clears very quickly. Is it possible for the fixer to clear the film clipping but still be unable to fix the film completely? Are there any other tests for fixers? Agefix is an Agfa product. With standard dilution, no replenishment, 1 liter will fix 1 square meter of film before the fixer is exhausted. That's about 20 rolls of 36 exposure, 35mm film. Here's a link to the Agfa film chemistry pdf. The Agefix info is on page 12 of the document. http://www.cri.ensmp.fr/~silber/photo/docs/films.pdf Stef |
#2
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Capacity/life of rapid fixer
"Stefan Patric" wrote in message ... On Sun, 04 Apr 2010 03:29:41 -0700, sreenath wrote: Hi, I am using a rapid fixer sold in India be the name "Agefix" The instructions that come with the bottle just suggests a dilution of 3-5 times for film. I have been using the suggested dilution with no problem. My question is the capacity of this diluted fixer. I kept using the 1 liter for more than a year. Every time I do a film clip test and observe that film clears very quickly. Is it possible for the fixer to clear the film clipping but still be unable to fix the film completely? Are there any other tests for fixers? Agefix is an Agfa product. With standard dilution, no replenishment, 1 liter will fix 1 square meter of film before the fixer is exhausted. That's about 20 rolls of 36 exposure, 35mm film. Here's a link to the Agfa film chemistry pdf. The Agefix info is on page 12 of the document. http://www.cri.ensmp.fr/~silber/photo/docs/films.pdf Stef The real test for fixer is the residual silver in the emulsion. There are two simple tests. One is about a 2% solution of sodium sulfide (not sulfite) the other is a 1:9 dilution of Kodak Rapid Selenium Toner. Either will tone the remaining halides or silver complexes readily leaving a stain. A drop or two of the solution is placed on _wetted_ film or paper and left for a couple of minutes, they rinsed off. It should leave NO stain if the emulsion has been completely fixed. With any fixer the capacity can be much extended by using two successive baths. This technique extends the ability of the fixer to completely fix from four to ten times. Instructions for the technique and for the test solutions can be found in the _Kodak Black and White Darkroom Data Book_ I don't know if this is still published but old editions have the same information in them. The problem is that an exhausted fixing bath will continue to clear emulsions long after it has become too exhausted to completely fix out all the silver halide. The complexes left in the emulsion will change over time to a form which can no longer be removed by re-fixing and will eventually destroy the image. -- Richard Knoppow Los Angeles, CA, USA |
#3
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Capacity/life of rapid fixer
All of the above suggestions are great but being the lazy person I am, I just use Agefix in 1+5 dilution in quantity of 1 litre, for 10 rolls of film and then make a new one. I am probably wasteful but it's not that expensive around here in 1.25 litre bottles, which makes 7.5 litres of fixer that lasts for 75 rolls of film. I don't even adjust fixing times.. |
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Capacity/life of rapid fixer
"sreenath" wrote in message ... On Apr 5, 3:24 am, Toni Nikkanen wrote: All of the above suggestions are great but being the lazy person I am, I just use Agefix in 1+5 dilution in quantity of 1 litre, for 10 rolls of film and then make a new one. I am probably wasteful but it's not that expensive around here in 1.25 litre bottles, which makes 7.5 litres of fixer that lasts for 75 rolls of film. I don't even adjust fixing times.. Hi, Thanks for all the information and suggestions. Hi, I mis-spelt the name as "Agefix". Actually it is "Agifix" When I searched on web for information, I thought it would be similar to Adefix of Agfa, but then was not sure. The bottle says "Rapid fixer for X-Ray and graphic industry". They don't explicitly state it is for regular films. It goes on to say : "Add 3.5 litres of water to the contents ....." meaning a total volume of working strength solution of 4.5 litres. So , I am not sure of the actual strength of the working dilution. I guess I will dump the fixer after about 20 rolls. Thanks, Sreenath If you can manage to find a data sheet for this stuff it would be worthwhile. X-Ray film has very thick emulsions, some are coated on both sides. They are harder to fix out that pictorial films so this fixer may be stronger than a standard fixer. Evidently AGFA used the same trade name for several fixers, the Agifix I am familiar with is a non-hardening fixer for color work that is nearly neutral in pH. That works fine for pictorial film and printing paper except you can not use an acid stop bath with it. A note: The potassium iodide test will show when there is a certain amount of silver in the fixer but is not quantitative. The test varies with the dilution of the test solution. The only test which shows if the fixer is working is to test the fixed emulsion for residual silver halide. That is done with either a solution of sodium sulfide or a 1:9 dilution of KRST, as I mentioned in a previous post in this thread. The iodide test may fail, that is, it may show the fixer as being good when it is actually too diluted for archival fixing. A two bath fixing method is a great help in achieving permanent images and is economical because it increases the capacity of the fixing bath by four to ten times. The use of a sulfite wash aid such as Kodak Hypo Clearing Agent will also help because it makes some not quite completely fixed complexes soluble so they wash out. -- Richard Knoppow Los Angeles, CA, USA |
#5
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Capacity/life of rapid fixer
"sreenath" wrote in message ... On Apr 6, 7:56 pm, "Richard Knoppow" wrote: "sreenath" wrote in message ... On Apr 5, 3:24 am, Toni Nikkanen wrote: All of the above suggestions are great but being the lazy person I am, Are there any alternatives to sodium sulfide for this test and in general for toning etc? I had about 500 grams of this stuff, and it absorbed water from air. I had to dispose it off. I would like to avoid having this chemical around because of the smell and its ability to fog photo emulsions. I use two bath fixer made from hypo for paper and have no confusion there as to degree of fixation. When I fix fiber paper I also use a sulfite wash aid. thanks, Sreenath Kodak at one time recommended a 1:9 dilution of Kodak Rapid Selenium Toner. This has low odor. I don't know how easy it is to get now. Its used in the same way as the sulfide test except that it must be used on well washed films or prints since it may fail to stain if there is an excess of hypo in the emulsion. Ideally, neither test solution should leave any stain if the emulsion is fully fixed. Micheal Gudzinowicz posted some very complete explainations of how fixer works to this group several years ago. I think Google will still find them. They are worth reading because they will give you a better understanding of the limits on fixer capacity. Clearing time is a dangerous criteria to use in judging fixer capacity since partially exhaused fixer will "clear" film long after it has reached the point where it is no longer fixing out completely. Because there are no longer enough free thiosulfate ions to completely convert the halide to water soluble form mearly extending the fixing time will not compensate for this. I use Kodak Hypo Clearing Agent on both fiber paper and on film. Because the emulsion on RC paper is so thin it washes out to archival level very quickly without any special treatment. The use of KHCA on it may actually wash it too much. The older ideas about archival washing were based on the idea that NO thiosulfate whatsoever should remain in the emulsion, however, about 1960 T.H.James of Kodak Research Laboratories discovered that very small amounts of thiosulfate remaining in the emulsion would stabilize the image silver resulting is some resistance to oxidation. This was such heresy that James was reluctant to publishe his results until similar findings from Fuji's lab were published. The discovery caused Kodak to revise its washing recommendations. KHCA can wash down too far if its applied for too long and subsequent washing is carried on for too long. Current Kodak recommendations for KHCA and washing times in general take cognizance of this. Its interesting that a great many "drugstore photofinisher" snapshots have survived because they were fixed OK but not overwashed where materials given "archival" washing treatment but no toning have developed the symptoms of oxidation, i.e., silvering of the surface and staining of the image. Toning is still the best protection. The Image Permanence Institute currently recommends a polysulfide toner like Kodak Brown Toner for this because it gives uniform toning for partial toning. KRST, which used to be the standard method was found not to be effective for partial toning. It does, however, provide good protection if some change in image density or color can be tolerated. The recommendation is to use a dilution no weaker than 1:9 and for not less than 3 minutes at room temperature for prints and films. -- Richard Knoppow Los Angeles, CA, USA |
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Capacity/life of rapid fixer
sreenath wrote:
Hi, How long will b/w prints last if fixed and washed properly, but not toned? I've seen a lot of early 20th century family photos which have survived just fine with normal storage in photo albums and envelopes. There are no guarantees (I think pollution can be a big variable), but there is nothing particularly unlikely about an untoned black and white print lasting a hundred years or more. Peter. -- |
#7
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Capacity/life of rapid fixer
"Peter Irwin" wrote in message ... sreenath wrote: Hi, How long will b/w prints last if fixed and washed properly, but not toned? I've seen a lot of early 20th century family photos which have survived just fine with normal storage in photo albums and envelopes. There are no guarantees (I think pollution can be a big variable), but there is nothing particularly unlikely about an untoned black and white print lasting a hundred years or more. Peter. -- That seems to be the case. If the films or prints are fixed thoroughly they should be washed according to Kodak recommendations. Since Kodak no longer makes B&W paper the usual recommendation is to wash single weight fiber paper for an hour and double weight for two hours in running water. If a sulfite wash aid is used 20 minutes is enough for single weight and half an hour for double weight. Since the washing is a slow process longer wash times are OK provided they are not extremely extended. The above is for water at about 68F (20C), washing is faster in warmer water. When a sulfite wash aid is used even quite cold water is effective. Washing is faster when a non-hardening fixing bath is used since the usual white alum hardener acts as a mordant for the thiosulfate when it is acid. By treating film or paper with a mild alkali the mordanting is eliminated. However, if the pH is much more than 7 (neutral) the hardening is also eliminated. Kodak Hypo Clearing Agent is buffered to neutral so that the hardening is preserved. The alkali also serves to affect the electrical charges in the gelatin so as to make it repel the thiosulfate ions where when it is acid it attracts them. Film washes out much faster than fiber paper because the support does not absorb any hypo. For untreated film fixed in a normal acid hardening fixer half an hour is enough. If treated in KHCA five minutes is sufficient. RC paper washes out in four minutes after normal acid fixer even when no wash aid is used and wash aid is not recommended by Kodak unless one is experiencing staining problems when toning. Polysulfide toner is the one recommended currently because it provides protection to all densities even when only partial toning is done. KRST tones the finer grains found in the high density parts of the image before it tones the coarser ones so that when highly diluted (1:19) KHCA is used as formerly recommended, the low densites may not be protected. If toning is carried out far enough it protects all densities. I don't know of another toner that can be used for partial toning and provide full protection against oxidation and sulfiding. The standard for microfilm is gold toning. It is quite effective and causes relatively little change in tone or density on cold or neutral tone paper. Its drawback is that its expensive. Gold will form fairly vivid blue images on very warm tone paper but on neutral or cold tone paper the color shift is small to none. Its useful where one finds a paper a bit green. Polysulfide toner is easy to make. Kodak gives a formula as Kodak T-8. According to the IPI this is as effective as Kodak Brown Toner for image protection. However, if you can't obtain polysulfide that isn't very useful to you. The theory about the small residue of thiosulfate is that it causes a slight amount of surface sulfiding of the silver crystals. Silver sulfide is very stable so once a layer of sulfide forms it goes no further and is also passive as far as oxidation is concerned. The problem is that there is no definite information about wash times, etc. Another anti-oxidation treatment involves the use of a chemical like thiocyanate in highly diluted form. This is what AGFA Sistan was. While Sistan was not as effective as toning it does have the advantage of not causing any change to the image color, density, or structure. The latter is of little consequence in pictorial photography but can be critical for microfilm. FWIW, _any_ sulfiding toner will fully protect images if carried out to completion, however all will change the image color. KRST will provide full protection according to Dr.Douglas Nishimura of IPI if used at a dilution of no greater than 1:9 and for not less than 3 minutes at 68F. Gold toners are very effective. Other toners such as iron, copper, uranium, etc, form imgages which are _more_ vulnerable than the original silver image although they may produce attractive colors. BTW, it has become much more difficult to obtain photographic chemicals even here in the USA. -- Richard Knoppow Los Angeles, CA, USA |
#8
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Capacity/life of rapid fixer
"Richard Knoppow" wrote in message ... "Peter Irwin" wrote in message ... sreenath wrote: Hi, How long will b/w prints last if fixed and washed properly, but not toned? found in the high density parts of the image before it tones the coarser ones so that when highly diluted (1:19) KHCA is ^^^^^^^^^^^^^^ Mis-typed, should read KRST i.e., Kodak Rapid Selenium Toner -- -- Richard Knoppow Los Angeles, CA, USA |
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