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Photo Forum / Film Photography / Darkroom / October 2006TF-3 alkaline fixer, sodium sulfite solubility problem
I just mixed a TF-3 fixer. Here is the formula I used: * Ammonium thiosulfate (57-60%) 800 ml Sodium Sulfite (anhy) 60 g ** Sodium Metaborate 5 g (50ml of 10%sodium metaborate/L) Distilled water to make 1000 ml ~ . ~ . ~ . ~ * To make ammonium thiosulfate: I mixed ammonium chloride 600g + sodium thiosulphate(penta) 1406g [900g for anhy ; divide by 0.64 (900/0.64), to get grams in penta] in 1.5 L of water. I used 800ml only per 1Liter of fixer. ** I made sodium metaborate from Borax 69g + 14.5g NaOH (tech grade,flakes) in 1L of water, for a 10% solution of sodium metaborate (100g/L); I used 50ml to get 5g. There was a very thin layer of white substances/flakes floating on top of the finished solution. Also, the sodium sulfite (photo grade, in white powder form) was very hard to dissolve. I heated the solution to 50degC before adding sodium metaborate, to help dissolve the sodium sulfite, but still it doesn't dissolve completely. There is still a considerable amount of sodium sulfite at the bottom of the solution up to now. Is this occurence normal for TF-3 fixer? I notice that the sodium sulfite in this formula is thrice the usual amount per liter, which is normally 15g/L. I assume that that is the reason why the sodium sulfite was incompletely dissolved. What else could I do to dissolve the sodium sulfite? Or should I just let it stand in the solution? Will it harm the fixer? If you notice any mistakes in the formula or the method, please post the corrections here. Thanks again to this wonderful forum. Footnote: I mix ammonium thiosulphate and sodium metaborate from scratch because the chemicals are not available here in my country. I wouldn't buy ready-made fixer now because I am at a phase where I want to learn to mix my own chemicals. > I just mixed a TF-3 fixer. Here is the formula I used: > [quoted text clipped - 11 lines] > thiosulphate(penta) 1406g [900g for anhy ; divide by 0.64 (900/0.64), to get > grams in penta] in 1.5 L of water. I used 800ml only per 1Liter of fixer. I'm no chemist, but I'd imagine that by mixing ammonium chloride and sodium thiosulfate, you'd get something in addition to ammonium thiosulfate -- probably sodium chloride. This could well be part or all of the cause of the problems you relate later in your post. > Footnote: I mix ammonium thiosulphate and sodium metaborate from scratch > because the chemicals are not available here in my country. > I wouldn't buy ready-made fixer now because I am at a phase where I want to > learn to mix my own chemicals. If you can't get ammonium thiosulfate but still want a rapid fixer, you might want to give Agfa 304 a try: water (125F/52C): 750ml sodium thiosulfate: 200g ammonium chloride: 50g potassium metabisulfite: 20g water to make: 1l This is Anchell's (_Darkroom Cookbook, 2nd Edition_) formula #123. Anchell says to fix paper for 3-5 minutes and film for 3x the clearing time. (I don't know why these values.) The formula does what you were trying to do -- it makes ammonium thiosulfate in solution from sodium thiosulfate and ammonium chloride. It was presumably designed with the sodium chloride (or whatever the reaction byproduct really is) in mind, though. I've never used this formula; I'm just passing it on because I remember it from the book. In what country are you located? Perhaps you could track down other local photographers to combine resources for obtaining necessary photochemistry.  SignatureRod Smith, rodsmith@rodsbooks.com http://www.rodsbooks.com Author of books on Linux, FreeBSD, and networking > > I just mixed a TF-3 fixer. Here is the formula I used: > > [quoted text clipped - 34 lines] > says to fix paper for 3-5 minutes and film for 3x the clearing time. (I > don't know why these values.) 3x the clearing time would seem way too long and also might begin to bleach out the silver. 2x is pleanty in my experience... > The formula does what you were trying to do > -- it makes ammonium thiosulfate in solution from sodium thiosulfate and [quoted text clipped - 5 lines] > In what country are you located? Perhaps you could track down other local > photographers to combine resources for obtaining necessary photochemistry. Clearing times in 'rapid" fixers. My rule of thumb is 2x for slow speed or conventional materials and 3x for modern emulsions like T-Max and fast emulsions like HP-5 or Tri-X. I've not tested this in a while since my film volume has slipped so low I now use liquid fixer, one shot, at paper strength, for fixing film with constant agitation. darkroommike >>> I just mixed a TF-3 fixer. Here is the formula I used: >>> [quoted text clipped - 46 lines] >> In what country are you located? Perhaps you could track down other local >> photographers to combine resources for obtaining necessary photochemistry. For Tmax one should fix until there is no dye left (i.e., until fb+f areas show no purple tint and are clear.) Whether it's 2x or 3x I don't know but this indicates complete fixing, at least for Tmax films. > Clearing times in 'rapid" fixers. My rule of thumb is 2x for slow speed > or conventional materials and 3x for modern emulsions like T-Max and [quoted text clipped - 53 lines] > >> In what country are you located? Perhaps you could track down other local > >> photographers to combine resources for obtaining necessary photochemistry. Tom Phillips a écrit : > For Tmax one should fix until there is no > dye left (i.e., until fb+f areas show no > purple tint and are clear.) Whether it's > 2x or 3x I don't know but this indicates > complete fixing, at least for Tmax films. I too fix more T-grain films than "normal" ones but I don't think you need to overfix just to remove the purple tint. If you use a washaid, I just use plain sodium sulfite @ 20gr/l, before the final wash, the tint is removed very easily. Claudio Bonavolta http://www.bonavolta.ch > If you use a washaid, I just use plain sodium sulfite > @ 20gr/l, before the final wash, the tint is removed > very easily. "Tmax Pink" washes out much faster if the wash-aid and wash water are ~75F. TMax films are [or so I think I remember hearing] less sensitive to higher temperatures. SignatureNicholas O. Lindan, Cleveland, Ohio Darkroom Automation http://www.nolindan.com/da/index.htm n o lindan at ix dot netcom dot com > Tom Phillips a écrit : > [quoted text clipped - 8 lines] > If you use a washaid, I just use plain sodium sulfite @ 20gr/l, before > the final wash, the tint is removed very easily. Not talking about over fixing (hard to do anyway...) The purple is a sensitizing dye that can also bind to silver halides and silver thiosulfate residues in the emulsion. If the purple/magenta color is very light it will wash out in Hypo Clear. If it's darker and more pronounced your film isn't being fixed long enough. I typically fix Tmax for 6 minutes in fresh fix and in my experience this isn't too long a fixing time for Tmax films. The stain is usually gone after 5-6 minutes in fresh fix. As the fixer gets saturated my fixing times can go to 7-8 minutes before discarding. Meaning if the purple isn't gone in about 7/7.5 minutes I discard the fixer. Kodak pub. F-4016 also states: Your fixer will be exhausted more rapidly with these films than with other films. If your negatives show a magenta (pink) stain after fixing, your fixer may be near exhaustion, or you may not have used a long enough time. If the stain is slight, it will not affect image stability, negative contrast, or printing times. You can remove a slight pink stain with KODAK Hypo Clearing Agent. However, if the stain is pronounced and irregular over the film surface, refix the film in fresh fixer. RE: Tom Phillips wrote:h > Kodak pub. F-4016 also states: > > Your fixer will be exhausted more rapidly with these films > than with other films. Rapid fixers are no longer "rapid" and capacity is much reduced due to the iodide. The ammonium ion has little affinity for silver in the presence of iodide. In effect the fixer becomes a sodium thiosulfate fixer. The thiosulfate ion does have the necessary affinity for silver in the presence of iodide to do the job. Ammonium and sodium silver thiosulfate complexes are soluble. Impurities in the water which form insoluble compounds with the thiosulfate complex may be another source of the pink. Such compounds can precipitate in the emulsion along with the dye. Test using only distilled water start to finish. Dan > RE: Tom Phillips wrote:h > > [quoted text clipped - 5 lines] > Rapid fixers are no longer "rapid" and capacity is much > reduced due to the iodide. Have to wonder why they call it Rapid Fix, then. I seem to get about the stated capacity Kodak lists. In any case I use it mainly due to it's ease of use (i.e., liquid concentrate.) And since I quit using powdered sodium fixers about 15 years ago I have no comparison data on rapid vs.sodium thio efficaciousness with various fixing times. The ammonium ion has little affinity > for silver in the presence of iodide. In effect the fixer becomes > a sodium thiosulfate fixer. The thiosulfate ion does have the [quoted text clipped - 5 lines] > Such compounds can precipitate in the emulsion along with > the dye. Test using only distilled water start to finish. Dan > > RE: Tom Phillips wrote:h > > > [quoted text clipped - 24 lines] > > Such compounds can precipitate in the emulsion along with > > the dye. Test using only distilled water start to finish. Dan Here's an interesting post from Richard 3 years ago... Subject: Re: Rapid Fixer Questions Date:Tue, 29 Apr 2003 20:57:47 -0700 From: "Richard Knoppow" <dickburk@ix.netcom.com> Ammonium thiosulfate fixes out faster than sodium at the same molar concentrations. However, the difference in speed depends on the emulsion. Ammonium fixer is most effective with emulsions containing a lot of silver iodide. That includes film emulsions generally but especially fast emulsons and tabular grain emulsions like Kodak T-Max, Ilford Delta, and Fuji Acros. Kodak Tri-X is also a very iodide emulsion which tends to fix out more slowly than other films. For these ammonium fixer is quicker and gives more assurance that the emulsion will be completely fixed out. For paper type emulsions there is less difference between sodium and ammonium although the ammonium fixer is still faster. However, _acid_ ammonium fixer has a tendency to bleach very fine metallic silver grains. These are plentiful in paper emulsions, which are excedingly fine grain compared to film. For that reason, and because paper fixing times are short whichever fixer is used, sodium fixer is to be preferred for paper. Tom Phillips With iodide present a rapid fix in effect becomes a more nearly sodium thiosulfate fix. That would have been a better way to put it. The slow down with rapid and decrease in capacity with both S and A fixers is due to the extreme insolubility of silver iodide. Thiosulfate forms a bond of such strength with silver that it can form an in solution complex. The ammonium ion will not do that to any meaning full extent although it's presence does quicken the process some little. I've no argument with an ammonium fixer being more rapid and in ALL cases, film and paper. How much faster? Dan > Tom Phillips > With iodide present a rapid fix in effect becomes a more nearly [quoted text clipped - 7 lines] > I've no argument with an ammonium fixer being more rapid > and in ALL cases, film and paper. How much faster? Dan Yes, that's a little clearer. Thanks. All of the TF- formulas, including the proprietary formula for TF-4, have solubility and precipitation problems, so mixing can be difficult. Nonetheless, the chemicals should go back into solution and the formulas will work. --Jon Mided Digitaltruth Photo http://www.digitaltruth.com |
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