|Processing Fiber Base Prints with Ansel Adams' Odorless and Cheap "Plain Fixer" from Bulk Chemicals|
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By Lloyd Erlick,
April 15, 1998.
Recently my darkroom activities have revolved around a quest for a fixer that did not stink -- and did not try to tear out my mucous membranes. I find so-called 'rapid' fixers much too harsh.
There are many formulas for conventional fixers. (A conventional fixer is based on sodium thiosulfate, the chemical that was originally, and erroneously, termed sodium hyposulphite, which explains the persistent term 'hypo' for the active fixer ingredient.) Most are fairly simple and straightforward, and the variations are mainly due to different functions. Hardening versus non-hardening is a primary difference. Acid versus non-acid is another.
Hardening is a venerable process from the early days of photography. Photosensitive coatings are notoriously soft and delicate, especially when wet during processing. A hardener is a substance added to a fixer (or sometimes a stop bath) to make the material tougher, or harder.
Modern day films and papers are much less prone to damage when wet. In fact, they need hardener much less, or not at all. I have never used a hardener in all my life. Careful working methods suffice to prevent damage to print surfaces.
An interesting fact about hardeners is that they demand an acidic environment. Therefore, when hardener is added to fixer, it must also contain an acid.
Acid in fixers is there for another reason: it halts development. Many people sloppily allow developer to be carried over to the fixer from the developer step of their processing. The use of a stop bath is recommended to prevent this. But even if a stop bath is used, a certain amount of developer will end up in the fix. Fix poisoned with developer is an excellent source of print stains. This is a problem we will address effectively and cheaply.
Thus, two components of common fixer formulas (acid and hardener) may be omitted as long as the darkroom worker observes careful practices: use a stop bath, and take steps to prevent developer from being carried over to the fixer.
These demands are easy to satisfy, and for zero cost, as well. After the developer step, rinse the print with plain water. Then immediately use a stop bath. To effectively eliminate developer from the fixer as well as prevent acid from entering the fixer, thoroughly rinse the print again, after the stop and before fixing it. I use two changes of plain water.
Prevent acid from entering the fixer? Acid in the fixer is not necessarily bad, but does have the potential to damage the fixer. The fixing agent, sodium thiosulfate, may be broken down by acid to precipitate sulfur, which destroys the fixer. This result is prevented by the sodium sulfite, the second main component of conventional fixer. Thus, rinsing the print thoroughly after the stop bath gives us double protection at no extra cost and very little extra effort. Belt and suspenders, if you will.
|THE FIXER AND SELENIUM TONER|
There is a much more serious additional reason to prevent acid from entering the fixer: if it is carried over to the selenium toner following the fixer, stains are certain to result. When an acid fixer, or acid-hardening fixer, is used, the rinse step must follow the fixer. Usually there is an additional step, with an additional chemical. This chemical is one of a number of alkaline materials meant to neutralize any trace of acid before it reaches the toner. Commonly Kodalk is used (a rather expensive chemical) in a two per cent solution. Sodium sulfite is more often used, again about two per cent. Either of these is harmless when carried over into the toner. And since the plain fixer under discussion here contains plenty of sodium sulfite, it fulfills this function without the need of a separate bath. Thus we are merely moving our rinse steps to an earlier position in the chain of steps, and eliminating one bath.
One of the most popular fixers is called F6. Kodak invented it many years ago. It was an advance over a previous fix they called F5, which had a powerful smell. Most people find this odor terrible, including me. It comes from sulfur dioxide gas liberated from the fixer. The major component of the fixer is a sulfur compound, sodium thiosulfate, which can release sulfur dioxide in the presence of acid. The acid had to be in F5 for the hardener to work, you see, so ...
Enter F6, which replaced part of its acid with a substance coyly named Kodalk. That's Kodak Balanced Alkali to us. In Toronto, in April, 1998, the Kodak version of this substance sells for about C$10.00 per pound. It is in reality sodium metaborate, a relative of Borax, the common laundry additive. Sodium metaborate also sells for far too much money, although less than when it bears Kodak's yellow label. My goal has been to make a cheap fixer, too, not just a sweet smelling one!
Next we go to page 192 of Ansel Adams' famous book, "The Negative." He informs us that in fixer F6, "Kodalk or borax" may be used. Borax makes it a good deal cheaper. It is worth noting that the term Borax can refer to any of three substances: sodium tetraborate anhydrous, sodium tetraborate pentahydrate or sodium tetraborate decahydrate. If you ever go out to buy a bulk load of Borax, never buy Borax anhydrous. It is virtually impossible to dissolve in water. You may find the pentahydrate at a good price, but it absorbs water from the air quite readily with attendant problems caused by caking. Storage of this material is a problem. The common laundry additive known far and wide as Borax is the decahydrate form, which dissolves easily and stores easily. It is also the form referred to in photographic formulas that use it, so there will never be any need to adjust the weight used. Buying it at the supermarket is perfectly adequate for darkroom purposes.
When mixing F6, one can follow the action by its smell. The formula starts with sodium thiosulfate, which when dissolved yields a faint, nondescript odor. Next sodium sulfite is added, which seems not to change the smell much. Then F6 calls for acetic acid, which certainly livens things up. Keep your head well away from the area directly above the mixing container; the warm water will be sending a column of air up above, and once the acid gets there you will not be able to miss the effects of sulfur dioxide, which is the gas liberated from this solution when acid is included.
Sulfur dioxide: can I regale you with a tale of my snide grade twelve chemistry teacher (circa 1966), who was bored with his job and fed up with teenagers? I have mercifully forgotten his name ... quote ...
"Sulfur dioxide is a gas that will dissolve in water. Once dissolved in water it forms sulfurous acid, which oxidizes readily to sulfuric acid. Human mucous membranes are wet. Wet means water. The mucous membranes in the respiratory system are well supplied with oxygen. Are there any questions as to the consequences of breathing sulfur dioxide?"
F6 is odorless, yes it is, so something must happen next. Indeed: Kodalk or borax is added. Instant odor elimination. I've done it so I know it works. It is very effective. The resulting solution is no problem to have around.
Next, the official F6 formula calls for hardener. No doubt many people still dutifully add hardener, but it is widely described as unnecessary. I have never used it. And it has the sad property of extending print washing times. For papers in the past (can we call them older-technology papers?) hardener was essential. Times have changed.
|ALTERING F6: PLAIN FIX IS THE RESULT|
What happens if we eliminate these non-essentials? F6 is an odorless (it really is. I've used it a lot, so I know!) fixer that contains hardener, which I never put in. So the acid can go, too, because it was there for the hardener. If we carefully use a stop bath to terminate the development process, and carefully rinse away the acid stop before entering the fix step, can we simplify the fix itself??
Yes we can. The classic, "plain" fix is described by Adams as well. He calls it 'plain hypo' fixer, but his formula actually has two components: sodium thiosulfate and sodium sulfite. The sulfite is often described as an oxygen scavenger. It has a powerful tendency to react with oxygen; this prevents the oxygen from reacting with the thiosulfate, which would shorten the life of the fixer. Thus, we can "modernize" the classic, olden times formula for fixer, sodium thiosulfate alone, by the addition of sodium sulfite to prevent it from oxidizing. This was probably considered modern a century ago. Its lifespan is equal to F6. Its capacity is equal, too.
So now we have a cheap, effective fixer that has only two components (three if you count the water!) and no smell.
We pay for its advantages by demanding of ourselves certain things before we enter the fixer step. We must use an acid stop bath, but this is no sacrifice. We should use one anyway. We must also rinse away the acid stop before the fixer step. This is a small sacrifice, too, and close to zero cost as well.
|PLAIN FIXER AND THE SINGLE-TRAY METHOD|
The single-tray method of print processing (described in another article on this website) lends itself to the processing style described here. It is very easy to rinse a print this way. The print need never be handled; there is no transfer of a wet sheet of paper from tray to tray. Even the bottom surface of the print is easy to rinse after a few minutes spent learning to rock the tray so a 'wave' passes under the print.
|GENERAL USAGE OF PLAIN FIX
AND MORE ABOUT SELENIUM TONER WITH PLAIN FIX
The 'plain fixer' advocated here is easy to prepare. Both components dissolve extremely easily. Both are commonly available in anhydrous forms, which dissolve at 80F rather than the usual 125F recommended for the hydrate forms of these chemicals. In fact, this fixer is so easy to prepare it would be little trouble to mix it up immediately before each session. Its capacity is about 25 8x10 equivalents per liter, so many workers would exhaust it in one day's work. Thus, keeping track of usage, and storage, may cease to be factors for some darkroom workers.
I find I am unable to exhaust this fix in one day's work. I tend to work slowly and contemplatively. I often have a session of serious work followed by a session of testing in preparation for the next serious session. Therefore, I store my fix and re-use it once or twice for the less serious testing work (which is not going to be kept, for the most part.)
Most black and white darkroom workers treat their prints with selenium toner. It has been established that selenium toner protects the image from attack by a number of airborne pollutants. One of the reasons we must prevent acid from the stop bath from getting into our plain fix is that acid carried over into the selenium toner can cause print stains. Many darkroom printers who use acid fixer treat the print with an alkaline bath before the selenium. Two per cent sodium sulfite, or one to two per cent sodium metaborate (Kodalk) are commonly used. By using the plain fix, this step can be eliminated.
The plain fix is somewhat alkaline, by virtue of its sodium sulfite content. There is no need to rinse after the fix. The print can be treated with selenium toner directly from the fix with no rinse or other intermediate step. This compensates for some of the time spent rinsing before and after the stop bath.
The fixer carried into the selenium toner is harmless. In fact, Kodak Rapid Selenium Toner (KRST) contains ammonium thiosulfate, a fixing compound. In the past, fixer was said to cause stains if it was carried into the selenium toner. But it is actually the acid in the fixer that causes staining if it is carried into the selenium. The fixer itself is harmless. This is a major reason for removing the acid from our fixer.
Naturally, a two-bath setup is recommended for fixing. I call them Fix1 and Fix2. The print is treated in Fix1 for 3 to 5 minutes, then treated in Fix2 for the same length of time. The lights can come on after the print has been in Fix1 for one to two minutes.
Fix1 does most of the fixing; Fix2, always being relatively fresh compared to Fix1, is always capable of completing the job. As long as Fix1 is never permitted to be overworked, prints need never be exposed to high concentrations of fixer byproducts, which can cause stains to appear years later. In fact, some workers, when making special prints expected to be valued for many years to come, will mix fresh fix for each individual print. Plain fix is cheap enough, and easy enough to mix, that such care may be taken when circumstances demand.
Fix1 will exhaust after 25 8x10 equivalents per liter have been processed. At this point, or before, discard Fix1 and replace it with Fix2. Mix a new batch of fix and use it as Fix2. You can see that over the course of time this procedure will cause each 'new' Fix1 to become progressively more used as the old Fix2 moves up to become Fix1. Our first Fix1 was fresh, never used, but when Fix2 moved up to replace it, now our new Fix1 was partly used. This slightly used Fix1 makes the newly mixed Fix2 even more used than the one in the first cycle by the time it moves up to become Fix1.... So it is recommended to follow this practice only three times in a row, at which point both Fix1 and Fix2 are discarded and two new fixing baths mixed.
|MORE ABOUT DARKROOM ODOR CONTROL|
While we're on the subject of odor control in the darkroom, here's another nice touch: stop bath need not be acetic acid, which many people find irritating. Acetic acid for stop bath can be replaced by citric acid, which is a fairly cheap and easily obtained white powder. In solution it is quite odorless. Use 15 to 20 grams citric acid per liter of stop bath.
Citric acid is commonly sold in supermarkets or bakery supply outlets. Bags of 25 kilograms or so can be purchased at very low unit cost from large scale chemical suppliers. The bags will often be marked "Kosher," and may also be marked "FCC" (Food and Chemical Codex.) These terms mean the contents are approved for use in Kosher cooking. Kosher citric acid is more than pure enough for darkroom use! It is interesting to note that several darkroom chemicals are commonly used in food industries, and the designation "Kosher" is not that unusual. I have purchased Potassium Carbonate in a 50 pound bag marked Kosher.
Acetic acid is a funny thing. Dilute it to the 1.3 to 2 per cent range, and it is photographic stop bath. People find it irritating to smell. But go to the supermarket and buy a container of 5 per cent acetic acid, and it's vinegar! Canadians put it on their chips and get funny looks in restaurants when they travel in the United States.
U.S. Borax Company website.
Jack's Photographic and Chemistry Collection.
... and a few more helpful humans:
|Copyright Lloyd Erlick. All rights reserved.|