Hi, I use Ilford Hypam to fix both my films and papers and I'd like to know how many times I can reuse a diluted solution? I don't process more than 2 films or 20 8x10 prints a week.

I understood people use the film leader to check to fixer but what if I just want to use it for print processing, is there anyway to check that the solution is still strong enough?

Regards, S.THAO

-- Stephane Thao (steph@santhy.net), September 07, 2001

Answers

Stephane: You should use separate batches of fixer for film and paper, as they use up the fixer at different rates. What information I have been able to gather about how many films and prints can be fixed with rapid fixer is available on my site at http://unblinkingeye.com/Articles/Archival/archival.html.

Ilford does not give a specific quantity of film you can fix with their rapid fixes, but Kodak says that one quart (or one liter) of film-strength rapid fix will process 32 8x10 inch negatives and, if you calculate square inches, a roll of 35mm or a roll of 120 are about equal to an 8x10 inch sheet film. My practice is to be a bit conservative--I mix up 2 liters at film strength and process 40 rolls in it, then replace it. I figure Ilford fixer probably works about the same way Kodak's does, so I use it the same way.

Ilford says that a liter of Multigrade fixer at working strength will fix 50 8x10 inch prints. I couldn't find that information for their Hypam Universal Fixer, but I assume it is essentially the same. My practice is to always use two fixes of 2 liters each, at film strength. I process 60 prints, then discard the first fix. The second fix is transferred to become the first fix, and I mix a fresh batch for the second fix. I don't use the solution to its full capacity, but I am assured of proper fixing under almost any circumstance.

-- Ed Buffaloe (edb@unblinkingeye.com), September 07, 2001.

Ed, Thanks for your answer.

I think Hypam can be used at 1+4 for both film and paper processing. Should I really use two different baths anyway?

I don't have a permanent darkroom so far (I'm new into photography) therefore I don't process films or papers too often (about once every other week). How long can i keep a diluted solution if I put it back into a accordion storage bottle after use?

-- Stephane Thao (steph@santhy.net), September 07, 2001.

Words of wisdom from Richard Knoppow, patron saint of USENET rec.photo.*:

Details can be found in the _Kodak Black-and-White Darkroom Dataguide_ along with a testing method for the two baths.

Start with two freshly mixed fixing baths. Fix the film or paper in the first for half the usual fixing time. Drain and finish fixing in the second bath for the other half of the time. For prints a water bath can be used between the two fixing baths so that all prints from a session are given the final bath at the same time, sometimes a convenience. The chemistry has been described in detail in a couple of postings by Mike Gudzinowicz to this news group. You can find them by doing an author search on Google.com Basically, the fixing process consists of converting the unused silver halide in the emulsion into a form which is water soluble and will wash out. When you wash film or prnts you are washing out not only the residual hypo but also some of the converted halide (some comes out in the hypo). This reaction is not a simple one, it goes in steps, each step a little more soluble than the previous one. At some point a single hypo bath can no longer complete the series of reactions so leaves some of the halide in an insoluble condition. If the print is left this way the insoluble silver complexes left in the emulsion will begin to decompose after a time and will also begin to attack the silver image. For this reason its very important to complete the fixing process if prints or films are expected to have a long life. It turns out that the capacity of a single bath is very limited, around 10 8x10 prints per _gallon_ for archival quality for prints. If two successive baths are used the first bath does most of the work and the second bath stays fresh enough to complete the reactions so that the silver complexes are in water soluble form. The capacity of a double bath system is four to ten times that of a single bath, which makes it an economy as well as insuring complete fixing. With this system when the first bath reaches exhaustion (as determined by an iodide test) it is replaced with the second bath, which is still relatively fresh. The second bath is replaced with a fresh bath. Since there is some carryover both baths should be replaced by fresh baths about every five times. Two bath fixing has a further advantage for film. Film emulsions invariably contain Silver Iodide. The Iodide ion comes out in the fixing bath and acts to slow down the fixer. The rather large amount of Iodide in T-Max films is one reason they take longer to fix than other films. Most, if not all, of the Iodide comes out in the first bath, leaving the second bath to work at normal speed. It is generally considered good practice to use separate fixing baths for film and papers due to the iodide left by film. While this is still good practice with a two bath fixer, it is not nearly as necessary since the second bath remains relatively iodide free. A note. I am not a fan of alkaline fixing baths. They really serve no useful purpose except where a dye image is concerned. While it is claimed that they have an advantage over conventional acid fixing baths in washing out faster, this advantage is present only in comparison with a hardening fixer containing aluminum sulfate hardener in a narrow range of pH. When a sulfite wash aid, like Kodak Hypo Clearing Agent, is used, the wash rates of films and papers treated in hardening fixing baths is no different than those treated in a non-hardening acid fixer or in an alkaline fixing bath. The acid in acid fixers has an advantage in that it prevents activation of carried over developer with resultant staining. The hardener is advantageous in preventing damage to the emulsion while fixing and washing. Wash aid is buffered to a point where it does not undo the hardening, as does a carbonate bath. Wash aid is also an ion exchange medium for thiosulfate so considerably accelerates washing, even over an emulsion treated in an alkaline bath. A wash aid is also effective in removing the residual sensitizing dye in T-Max films, generally it all comes out in the wash aid which turns a light purple color, once popular for ladies foundation garments (which dates the color and me).

Here is Kodak's version of fixer tester and instructions. Kodak Fixer Test Solution FT-1

Water at 80F 750 ml Potassium Iodide 190 gm Water to make l liter

This is about a hundred year supply, scale it down to something more reasonable. The instructions are: Testing a single bath fixer: To 5 drops of the test solution add 5 drops of the fixing bath and 5 drops of water. Discord the fixer if a yuellow-white precipitate forms instantly. Disregard any slight milkiness. Two-Bath Fixer: First bath--/test as descrubed abivce fir a single-bath fixer. Second bath--To 5 drops of test solution, add 5 drops of the fixing bath and 15 drops of water. If both tests produce a yellow-white precipitate, replace both baths with fresh baths. If ony the first bath forms a precipitate, replace the first bath with the second and the second with a fresh bath. The stock solution can be stored in a closed bottle for one year.

Edwal Hypo Check is the same stuff but probably at a different strength.

-- Tim Brown (brownt@flash.net), September 07, 2001.

I like to keep my film and paper fixers separate so I can keep track of how many rolls or sheets I have processed in each. I don't really trust the hypo test solutions to be accurate. I put a piece of black photographer's tape on each bottle of fix and make a mark on it with a white greasepencil for every 8x10 sheet of paper or film processed in it.

-- Ed Buffaloe (edb@unblinkingeye.com), September 07, 2001.

Stephane,

I have a small datasheet from Ilford for Hypam:

Diluted 1+4 its capacity is 24 rolls of 36exp. film

For RC paper: 80 8x10's (I'm assuming a 1+9 dilution here)

For Fiberbased paper: 40 sheets.

Now, all of this is fairly uninteresting from your point of view because the storage life for diluted fixer is very short: 7 days.

My advice would be to buy it in large quantities (5 liters or something there-abouts). That will help you keep the price down. At that point it will be cheap enough that I would simply remix a new batch when it doubt. Price-wise it's a question of quarters, but the damage done (and first seen years down the road) is considerable by comparison if you use an exhausted fixer.

I mix up a batch a day. If I'm going to work two days in a row, I save the fixer for the next day. Otherwise I just always mix a fresh batch. It's not worth taking a risk with bad fixer.

Regards, Daniel Ridings

-- Daniel Ridings (daniel_ridings@yahoo.se), September 08, 2001.

ILFORD HYPAM fixer is similar enough to the Multigrade fixer that capacities are the same. Mulitgrade fixer cannot be used with a hardener.

For film, ILFORD recommends a capacity of 19 rolls of 135-36x films per liter of working solution. It is possible to get slightly more with extended times, but this should not be carried too far, as it is impossible to tell from looking if the fixer has removed all of the argentothiosulphate compounds. A second fixer bath, as has been mentioned, will assure complete fixing even if the first bath is pushed beyond normal capacity.

For paper, we recommend a capacity of no more than 40 RC or 10 Fiber based prints per liter. This does increase to 40 Fiber based prints if following the ILFORD Archival Processing Sequence, as the second fix and the wash aid bath ensure that all residual compounds are removed.

The film chip test is by far the best way of testing the fixer. This will work with either film or paper fixer. Tests such as Edwal's Hypo Check will show if the fixer has become saturated with silver, but will not tell you if the fixer has become less effective due to other reasons.

Although it is stated on the bottles that the storage time is 7 days for the working solution, I have found that it usually keeps much longer, as long as it is kept in a closed bottle. Generally, if the capacity has not been reached, and there is no sediment in the bottle, it will probably still be usuable for several weeks with no problem. Of course, it is a good idea to check with the film chip anyway.

We do recommend keeping seperate fixers for film and paper, due to the buildup in different waste products from the two materials. In a pinch, you can use the same fixer, but overall capacity will diminish.

Although ILFORD generally recommends using fixers at 1+4 dilution for paper processing, this is done to improve speed of fixing, and therefore subsequent wash times. Capacity of the fixer is determined by the amount of silver present in solution, so a liter of 1+9 fixer has about the same capacity as a liter of 1+4, although fixing times will have to be extended.

David Carper ILFORD Technical Service

-- David Carper (david.carper@ilford.com), September 10, 2001.

A comment, and a question for David at Ilford. First, ditto on the two-bath fixing method either with standard or rapid fixers. Note that the capacities recommended by Ilford (and I presume Kodak as well) change with designated end use of prints. I quote their fact sheet "Processing B&W Paper": "A silver level of 2g/l is safe for all commercial use with fibre base papers. This approximates to 40 20.3x25.4cm (8x10 inches) prints per litre of working strength fixer (one bath method!). For prints with maximum stability, that is, for long term storage, a silver level of 0.5g/l should be used (approximately 10 20.3x25.4cm (8x10 inches) prints." The two-bath fixing method extends this capacity. Again I quote: "The capacity of a fixer can be significantly increased, while still obtaining optimum permanence, by using a second fixing bath. When the silver level of the first bath has reached 2g/l (approximately 40 20.3x25 . 4cm prints per litre of working strength fixer), discard it and replace it with the second bath. Make up a fresh second bath. This cycle can be repeated up to four times but, in any case, replace both baths after one week." For further info, download the PDF version of the above document from the Ilford web site.

Now my query for David: I have recently been using Ilford Hypam mixed 1:9 for film (not paper) and using it one-shot. My guide for fixing times is to fix for three times the clearing time which is determined by a clip-test. The times are longer, but the negatives processed in this manner pass my residual hypo and residual silver tests. In this way I can avoid mixing and storing working strength film fixer and just mix the amount I need to fix the batch of film I'm developing at the moment. Also, since I use pyro, this cuts down on fixer loss due to developer contamination. The capacities are arrived at by using the Ilford recommendations with a generous "fudge factor". Is there any disadvantage at all to this method as concerns film longevity, complete fixing and washing (my test seem to indicate not)? And why is this practice not mentioned or recommended since it is more economical, more environmentally sound, and, for us small batch processors, eliminates the need to store partially used fixer for the next batch? Any ideas/responses would be welcome, particularly from the Ilford tech department.

Regards, ;^D)

-- Doremus Scudder (ScudderLandreth@compuserve.com), September 11, 2001.