Two-bath fixing - trying to be more rigorous

[chris_waller]

<p>First a bit of a heads-up then some questions.<br>

I began using two-bath film fixing some seven years ago following a posting by Dan Schwartz of Dr Michael Gudzinowicz's paper on the subject. After some experimentation I have settled on the following regime for fixing which is based not on time but on numbers of inversions of the tank. I invert the tank continuously. I use Ilford Hypam/Rapid Fixer at 1+4 dilution and make up 1.5 litres, sufficient to fix 36 films according to Ilford's recommendations on fixer capacity. When Fixer 1 has fixed its maximum number of films, it is discarded and Fixer 2 becomes Fixer 1, while a new batch of Fixer 2 is made up.<br>

Starting with fresh solutions for both Fixer 1 and Fixer 2, for the first 5 films to be fixed I give 30 inversions, rest for 1 minute, then give 30 more. Testing with a piece of scrap film confirms that 30 inversions in fresh fixer clears the film. Then I rinse the film in water at 20 C, then I pour in Fixer 2 and give 30 more inversions. (The film is then washed using the Ilford Method.)<br>

After 5 films have been fixed, I increase the number of inversions of the tank in Fixer 1 to 35, so the next 5 films get 35 inversions, rest, 35 inversions, rinse, then 35 inversions in Fixer 2.<br>

After 10 films have been fixed, I increase to 40 (40 , rest, 40, rinse, 40 in Fixer 2.)<br>

So, after every 5 films I increase the number of inversions in Fixer 1 by 5 until the last 5 films to be fixed (films 31-35) get 60 inversions (60, rest, 60, rinse, 60 in Fixer 2.) Again, testing with a piece of scrap film confirms the clearing time.<br>

After fixing 35 films I tested both Fixer 1 and Fixer 2 for silver content using Merck Fixer test-strips. Fixer 1 had 3 gm/litre of silver (perhaps just a little over): Fixer 2 showed no measurable silver content. The pH of both solutions remained at 4.<br>

The silver content of Fixer 1, even after 35 films, is well within the recommended maximum level given by most sources (Merck recommend 3 gm/litre maximum) - I have seen some sources suggest that a fixer silver content, for film fixing, can be as high as 8-10 gm/litre. Any thoughts on this?<br>

Since Fixer 2 shows no measurable silver content even after 35 films, I am considering reducing the number of inversions in Fixer 2 to 30, regardless of the number of films fixed. Any thoughts on this?<br>

Finally, when using two-bath fixing, most schools of thought recommend discarding both Fixer1 and Fixer 2 after 5 cycles (Fixer 2 -> Fixer 1) and starting again with fresh solutions. Given my results, is this really necessary?<br>

TIA for any comments.</p>

[Alan Marcus]

<p>My my you describe a inclusive system. Don't think anyone can improve. If your films are profusely wash, archrival results will be achieved. A good indicator of fixer exhaustion is<br />time to clear. When the clearing time double, the fixer is presumed exhausted. Another test is; prepare a reagent, 5% solution of potassium iodine, add 1ml to a test tube containing 25ml of fixer and shake; if the fluid in the test tube becomes cloudy, the fixer is exhausted.</p>

<p>As a rule of thumb 30 sheets 8x10 film - 100 sheets 4x5 - 30 120 films, 60 35mm per liter of fix then discard. </p>

<p>As to the two fix bath method, the fist bath is used until time to clear doubles or the tally of films equals above rule of thumb or chemical test reveal exhaustion. The first fix bath is discarded, the second fix bath moves to the first position, a fresh solution becomes fix bath #2.</p>

<p>Continuous operations depend on replenishment of all solutions. You can add fixer replenisher based on a calculation of area of film process. This is the method I would use.</p>

<p>As to agitation (inversion), you can't over agitate in the fixer so long as physical damage is not occurring. My though is, your method is overaggressive. I would volt for continuous agitation for the first 30 seconds followed by 5 seconds agitation every 30 seconds. </p>

<p>The silver content of a well used fixer in a continuous film machine can exceed 8 to 10 grams per liter. However, I never allowed a silver count greater than 2 grams per liter. Above this count, the silver will likely plate out on tanks walls and racks and clips. </p>

[bgelfand]

<p>I just finished printing some Kodak Plus-X negatives that I exposed in 1966, 1969, and the mid-1970's. The negatives from 1969 were developed by the Army PX (Post Exchange) in Germany; the 1966 and 1970's negatives were developed by local camera stores in Berkeley, CA and Los Angeles, CA. I doubt any of these negatives had a two bath fix. I do not see any deteroration, but I have not examined them under a microscope - nor do I intend to do so.</p>

<p>I do not know how long these negatives will last, but if they last another 20 to 30 years, they will very probably outlast me, and that is all that counts.</p>

<p>So, I shall continue to simply use a one bath fix for my black and white film.</p>

[paul_hoyt]

<p>This is the first time I have read about a 2 bath fixing regime for negatives. The two bath process is usually reserved for fiber based paper to reduce the amount of impurities [from fixing] that can dissolve back into the paper base. Since film is plastic, the impurities do not dissolve back into the film base. The two bath system can not hurt film, but I question any possible advantage.</p>

<p>Paul</p>

[dhbebb]

<p>2-bath film fixing is recognised as giving archival permanence - the nice thing is it takes no longer than one-bath and saves fixer. You can study the process in detail out of interest, but it can be worked very simply on the basis of using bath 1 until the clearing time reaches a maximum of twice that of a fresh bath and then moving bath 2 up to 1 and making a fresh bath 2. The advantage is simply that fixing is always perfect, as with a totally fresh fixing bath, but there is no need to rigorously monitor and log throughput.</p>

[christer_almqvist2]

<p>Chris,</p>

<p>I think you overdo it.</p>

<p>Like BG I have old negatives, mine are from the 50s, and there has been no damage to them although I then reused developers and fix until the limit prescribed by the manufacturer. And I had no running water in my study that doubled as a darkroom.</p>

<p>Not that long ago I made simple check on the effect of agitation on print development. I exposed a sheet and then cut it into two pieces, developed one with more or less continuous agitation and the other half with agitation for the first ten seconds, and then once half a minute later. At the end of the process I put the two parts together using sticky tape on the back. I could not see any difference between the two parts.</p>

<p>I too use the Ilford method for washing films. I am careful to avoid unnecessary carry over from one bath to the other and for the last few baths I let the film rest for a minute or so in the wash water to allow time for the diffusion. With Kodak film, the last wash water is then complete free from anti halo color.</p>

<p>BTW, I am much more careful with film developer, scared as I have been about the rumors of developer sudden death. The first thing I do in the development process is to develop the film leader in full light, and then fix. By the time that is finished, I am set up to do the real development. I have never had a blank leader, but as the extra work and time involved is minimal, I think it is worthwhile to be sure that the developer is OK - before developing the film.</p>

[dave_wilson1]

<p>When it comes to black and white, I have no mind. When I started my journey in serious b&w about 1985, I took a few classes, had a few mentors and bought a few books. Like many, I own the three Ansel Adams manuals and for me they are my method of operation with little deviation. Ansel says, regarding both film and paper, don't over fix and be especially careful of overfixing using rapid fix. He was not a fan of any rapid fix, although he does mention an archival fixer by Ilford that keeps fixing time short (circa 1984). He also mentions use of a slightly different formula by Edward Weston that supposedly produced a different tone in the paper results. Comparing your method to Ansel's recommendations, I would think you are over doing it. I also frequent the John Schaefer Zone System book and he also emphasizes the point of keeping fixing short and not over doing it. He also goes into quite detail about using two fixes for fiber prints, which I have done myself. Again he stresses short fixes with a water bath in between so as not to have the fixer invade the fibers.</p>

[chris_waller]

<p>Thanks all for your replies. From my own measurements and the comments here I have decided to reduce the Fixer 2 time since that seems unnecessarily long.</p>

[jay_de_fehr]

<p>Has anyone ever over-fixed film? If so, how do you know? Of all the potential problems with processing B&W film, I think this one is the least of them, and surely less than under-fixing. The fix I use clears TMY-2 in about 20 seconds, but I fix for a full minute with no adverse effects, and I don't bother with two fixing baths, though I recognize the theoretical advantages. </p>

[dave_wilson1]

<p>John Schaefer "Zone System" p. 74: "... the image will begin to bleach, particularly in the thin parts of the negative. These correspond to shadow areas in the print."<br>

Ansel Adams "The Negative" p. 191: "This bleaching effect is first visible in the low-density areas..." Also of note regarding excessive fixing Ansel mentions: "... it can lead to sulfiding of the silver, ..."<br>

So, I guess if your low-density areas start to go to the sewer you know you fixed too good.</p>

 

[chris_waller]

<p>Jay,</p>

<p>That's a good question. I note Dave's comments from Ansel Adams and looked in 'The Negative', pages 191-192. Adams writes:"Excessive fixing must be avoided, ... the fixer may begin to bleach the image by removing silver as well as the unreduced halides. This bleaching effect is first visible in the low-density areas (the shadow areas on the negative, high values on the print). The rapid fixer formulas are especially likely to bleach image silver and must not be overused."<br>

My motivation for going to two-bath fixing was to be absolutely sure that my negs were fully fixed. I note also Brooks' comments. I, too, have some very old negs that were most likely processed rather hurriedly and given a quick dip in the fixer. Nonetheless, they are still printable after several decades, so maybe I am being a little over-zealous, but being the obsessive I am, I like to be thorough.<br>

I don't see any sign of image bleaching but I accept Adams' cautions. Perhaps when rapid fixers first appeared, people were not entirely confident that they were truly fixing the negs and so continued to fix for the sort of times that they used with plain old hypo. Adams warns that they (rapid fixers) "must not be overused", but he does not give any indication of what constitutes overuse. Since my aim is to produce durable negs, I certainly don't want to bleach out image silver, but I'm as certain as I can be that I am not overfixing. That said, I have no information on what one would have to do, timewise, to cause loss of image silver.<br>

Some people, using single bath fixing, use the 'twice clearing' time rule for fixing time. Others use 'three times clearing'. What I am doing is three times clearing time, but with effectively fresh fixer for the 'thrid time', as it were. In light of some of the comments made above, I am reducing the time in Fixer 2, to avoid any likelihood of image bleaching.<br>

Just out of interest, does anyone have any information on image bleaching by rapid fixers, i.e. to what extent one would have to over-fix to cause loss of image silver?</p>

<p> </p>

[jay_de_fehr]

<p>I'm aware of the warning first published by Adams, and repeated by others, but I'm not aware of anyone publishing actual data regarding the bleaching effect of fixer, rapid or other. I was not able to produce measurable silver reduction with even my super-rapid fix at 5X clearing. I'm not saying it's impossible, but I don't believe it's worth worrying about. Another way to think of it is to ask how effective is fixer as a reducer? I think you'll find the answer to that question to be; not very effective. </p>