Fixers formulas

If the maximum degree of pyro stain is desired, use a fixer that contains a minimal amount or no sodium sulfite. Sodium sulfite is a salt, and salt inhibits image stain. However, sodium sulfite is used in fixers as a preservative. Although the sulfite can be removed from any fixer formula, fixers without sulfite will not last beyond a single day s use. Plain Hypo is an example of a fixer with no sulfite. 

Using the same general formula that we used for K, we can examine constants for the formation of complex ions and determine what woulcfbe the best substance to use as a film fixer in other words, what substance can remove a large number of silver ions from the unexposed portion of the film. We use the symbol Kf for the formation constant of a complex ion. We know that thiosulfate ions are combined with silver ions to form the Ag(S203) 23- complex ... 

Film also takes longer to fix at low temperatures. When temperatures drop below 65F/18C fixing time will need to be extended. Observe how long the milkiness takes to disappear from the surface of the film and multiply that time by three. Below freezing a thiocyanate fixer should be used (Formulas Fixers Defender 9-F RapidThiocyanate Fixer). 

Alkali fixers, especially those compounded with ammonium thiosulfate, are the most efficient and effective with modern emulsions in both film and paper. Although they have been used for scientific purposes since at least the 1930s, they have only recently become commercially available. Photographers Formulary TF-4 is the first to be widely distributed. The formula forTF-3, a fixer having similar properties but a shorter shelf life, is given in the Formulas section. 

For tray processing of paper it is not necessary to use hardener unless you habitually experience scratches on the print emulsion from handling. If scratches do occur, hardener should be added to the fixer. Start by adding one-third of the manufacturer s recommended amount and increase in one-third increments until the problem is eliminated For example, if the directions call for 45.0 ml of hardener, start with 15.0 ml if the problem persists, add another 15.0ml. It will be necessary to neutralize or wash out the hardener prior to most toning processes (Formulas Miscellaneous De-hardener). 

Using a liquid hypo check (Formulas Miscellaneous Fixer Test Solution) is a reliable means to test fixer exhaustion but only If you are accurate in your measurements and testing procedure. The potassium iodide must be 10.0 ml of a 4% to 5% solution, and the amount of hypo tested should be exactly 100.0ml. To create a precipitate, the combined solutions must be shaken otherwise the test is prone to errors. 

The minimum fixing time is twice the time it takes the film to clear in fresh fixer. With some concentrated formulas such as Ilford Rapid Fixer or Photographers Formulary TF-4 the film may be clear in 15 to 20 seconds. Even so, I recommend a minimum fixing time of 3 minutes for all films and fixers, except for those that are meant for extremely rapid fixing, such as Defender 9-F Thiocyanate Fixer. This is not a scientific recommendation—it is my recommendation. One extra minute or two of fixing time will not adversely affect the film and it will help insure complete fixation as the fixer ages. 

Not all papers tone equally well, and color effects can be harder to achieve with some paper/toner combinations than with others. Others may respond well to one toner and not another. Also, the color of a toned print depends on the formula of the toner and its dilution the paper type, surface, and paper base tint and not least of all the processing method. This last includes not only the print developer used but often the choice of fixer. 

If a fixer with hardener has been used re-fix in Plain Hypo (Formulas Fixers Plain Hypo) or use Dehardener (Formulas Miscellaneous Dehardener) before toning. 

Fixer that has been partially exhausted will cause bleached prints to stain more easily. At the same time, ferricyanide bleach rapidly destroys fixer. Use fresh fixer and discard after the bleaching session after neutralizing it by dumping the remaining bleach solution into it. Plain Hypo is useful for this purpose as it uses only one ingredient and must be discarded after use anyway (Formulas Fixers Plain Hypo). 

Do not use an acid stop bath. Use a water rinse for 30 seconds to 1 minute. A good fixer to use with this formula is Photographers FormularyTF-4. 

F-5 is the standard sodium-thiosulfate-based formula. Many commercially marketed fixers are essentially unaltered versions of this formula. Use this formula for film and paper when hardening is desired. 

Most fixers have strong odors caused by sulfur dioxide. The substitution of balanced alkali for boric acid in the F-6 formula eliminates the odor almost entirely. 

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