Fixing: single vs double bath

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wiggywag

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How important is double bath fixing compared to a single bath?

I use only FB papers. I have a nice Archival washer, so my washing should be good :smile:
 

mts

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You can test the result of your fixing with a silver nitrate solution. Details are in Kodak publications. If the test shows fixing is complete, it does not matter whether you use one or two baths. Two baths are used mostly for production environments to obtain maximum life from the fixers before discarding. The second bath is discarded and the first one becomes the second bath with new fixer for the first one. Fixing is either complete or not so if your present method works there is no need to change it. If you are not re-using fixer you are unlikely to exhaust the one bath.
 

Anscojohn

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How important is double bath fixing compared to a single bath?

I use only FB papers. I have a nice Archival washer, so my washing should be good :smile:
********
I won't know how archival my fb processing is for another 125 years or so. In the meantime I use the standard two-bath approach, with a third straight hypo bath before dilute selenium toner. So far, so good (ca 50 years).
 

CuS

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Huh?

The second bath is discarded and the first one becomes the second bath with new fixer for the first one.

should it actually be the other way around - discard the first and move up the second?
 

jeffreyg

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I also use a two bath technique. Kodak Rapid Fix with no hardener. I believe if you use an acid stop bath before fixing the first fixer will become quite acid by the end of your session. I follow fixing with Rapid Selenium Toner with some hypo clear and the hypo clear before washing. I've used this for over thirty years with no apparent change in the prints having used a variety of FB papers. I say if the prints are important to be made, go with archival process.
 
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wiggywag

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I also use a two bath technique. Kodak Rapid Fix with no hardener. I believe if you use an acid stop bath before fixing the first fixer will become quite acid by the end of your session. I follow fixing with Rapid Selenium Toner with some hypo clear and the hypo clear before washing. I've used this for over thirty years with no apparent change in the prints having used a variety of FB papers. I say if the prints are important to be made, go with archival process.

What stop bath do you recommend?
 

timk

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i use 2 bath fixing for FB paper. It's good insurance against under-fixing and you do tend to get more mileage out of the fixer
 

nworth

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Two bath fixing has some advantages if you are doing a lot of printing. The method makes the most out of the fixer's capacity and assures adequate fixation throughout the session. You fix your prints for half the recommended time, with agitation, inthe first bath, then transfer them to the second bath for the remaining time. Most of the fixing happens in the first bath, which become loaded with silver complexes. After it is exhausted (Kodak says 200 8X10 prints per gallon, roughly 50 per liter), you discard the first bath, start start using the second bath as the first bath, and prepare a new second bath. Discard both baths after the equivalent of 1000 8X10 prints per gallon (250 per liter) have been fixed. If you only process 10 or 12 prints in a session and are not in the darkroom every day, the two bath method makes less sense. You would do better by mixing up a single fresh batch of fixer for each session.
 
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wiggywag

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I got this private message from Ian C,which I found very helpful:

"I’m surprised anyone thinks that 2-bath fixing is controversial. I read the recommendations and the reasons for doing so many years ago in books written by the personnel of Eastman Kodak. I believed then as I do now that they were the most authoritative source of photography materials knowledge. I started darkroom work in 1987. One of my coworkers gave me a single film-developing and printing lesson in his darkroom. He used single-bath fixing. He told me that people who process a greater volume usually use 2-bath fixing, but he didn’t do that. He simply discarded his fixer after 25 8” x 10” prints. It works, provided you’re good at keeping track of the number of prints you’ve fixed and don’t “cheat”. After I’d done this a couple of years, I noticed that some of my older Kodak Polycontrast prints had ugly purplish stains on them. It takes a few years of reaction with the oxygen in the air for this to become evident, but then it’s too late.

I did some reading of Kodak books. The stains matched their descriptions of “inadequate fixing”. Further reading suggested that I could eliminate the problem by 2-bath fixing. I practiced this from that point on and never had another stain-ruined print. You may already know this, but I think it’s worth repeating. In 2-bath fixing, fix 1 does the majority of the work, even if it has become weak. Then bath 2 only has to dissolve any small amount of unexposed silver salts that remain. After 25-30 8” x 10” prints (2000-2400 sq. inch) you scrap fix 1 and the partially used fix 2 becomes the new fix 1. Of course you need a new fix 2. You repeat the process every 2000-2400 sq. inches of processed paper. In this way you always have a relatively strong fix 2 ready to intercept any unexposed silver salts still remaining in the print after fix 1. It’s a clever idea, gives you maximum use of your fixer, and guarantees complete fixing so that you prints are permanent with respect to fixing. I can’t imagine why anyone would do otherwise."
 

RalphLambrecht

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...Fixing is either complete or not...

The problem is, fixing is never entirely complete. To decide on two-bath over one-bath fixing depends on how complete you want it.

During fixing, undeveloped non-image silver is dissolved by thiosulfate without damaging the metallic silver image. The first fixing bath does most of the work but becomes increasingly contaminated by the soluble silver thiosulfate and its complexes. Soon, the entire chain of complex chemical reactions cannot be completed successfully, and the capacity limit of the first fixing bath is reached. A fresh second bath ensures that all remaining silver halides and silver thiosulfate complexes are dissolved. An intermediate rinse is optional, but it protects the second bath from contamination. Fixing time must be long enough to render all residual silver halides soluble, but not so long as to allow the fixer and its by-products to permeate the paper fibers; the former being far more important than the latter.

So, one-bath fixing works, but it has some disadvantages: longer fixing times, fixing never as complete as two-bath fixing, residual fixer penetration deep into the fibers, leading to longer and not as effective print washing.

...If you are not re-using fixer you are unlikely to exhaust the one bath...

Correct, but if you do not change the fixer after every print, you are reusing fixer.
 
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wiggywag

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So, one-bath fixing works, but it has some disadvantages: longer fixing times, fixing never as complete as two-bath fixing, residual fixer penetration deep into the fibers, leading to longer and not as effective print washing.

Do you say that two bath fixing time is shorter than one? Could you please explain? What is your personal procedure?
 

RalphLambrecht

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Do you say that two bath fixing time is shorter than one? Could you please explain? What is your personal procedure?

Yes, two-bath fixing is shorter than one. Take your current one-bath fixing time and split it in half. Now fix sequentially for that time in two baths (where the 2nd is always fresh), and your print will have less residual thiosulfate than with the previous method, because the 2nd fix is always fresh. Consequently, you can fix for less time with two-bath fixing to get the same result.
 
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wiggywag

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Yes, two-bath fixing is shorter than one. Take your current one-bath fixing time and split it in half. Now fix sequentially for that time in two baths (where the 2nd is always fresh), and your print will have less residual thiosulfate than with the previous method, because the 2nd fix is always fresh. Consequently, you can fix for less time with two-bath fixing to get the same result.

Im not getting this perfectly. Say my normal fixing is 5 minutes with one bath fixing. I then split the time in half, 2.30 minutes. This is my new fixing time. 1.15 minutes I use in the first bath and 1.15 minutes I use in the second bath. Is this the way I should understand it?
 

RalphLambrecht

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Im not getting this perfectly. Say my normal fixing is 5 minutes with one bath fixing. I then split the time in half, 2.30 minutes. This is my new fixing time. 1.15 minutes I use in the first bath and 1.15 minutes I use in the second bath. Is this the way I should understand it?

No. If your single-bath fixing time is 5 minutes, split it in half and fix for 2 1/2 minutes in each fixing bath with two-bath fixing. It's just that the two bath fixing will fix more thoroughly and fixing for two times 2 minutes will be sufficient as well. So, 5 minutes once turns into 2 minutes twice.
 

RalphLambrecht

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OK, quick question.

If I start double bath fixing today with 2 fresh batches of fix, where the recommended rate is 40 sheets, would I ultimately use the original second bath for 80 sheets before it gets discarded? (does that make sense? It does in my head! :wink: )

Yes, the 2nd bath fixes 40 sheets as 2nd bath and afterwards 40 sheets as 1st bath before it gets discarded. However, measuring silver content is better than counting sheets, and if you count sheets, don't forget to count test strips too.

A little hint:
Don't discard your old fixer after a printing session. Discard it in the middle of the session, after test strips and work prints are done. This way you get fresh fixer for the final prints.
 

MVNelson

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any comments on on ILford's archival fixing recommendation ... basically highly conc. fix for very short times ?
 

RalphLambrecht

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any comments on on ILford's archival fixing recommendation ... basically highly conc. fix for very short times ?

That's the preferred technique. The logic is sound, fix as short as possible, and that's what I use and recommend for two-bath fixing. I fix paper in film-strength fixer.
 

Ian Grant

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The reason for the short fix times is so that the partially soluble Silver Thiosulphate complexes formed during fixing have little or no time to diffuse into the Fibre base where the can form weak bonds with the cellulose. This is the why staining from poor fixing is often in the paper, even on the rear not just in the emulsion.

Ian
 

MVNelson

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It's what I have been doing all along. I still do a longish wash after Permawash bath. I use T4 for film but for paper I use Hypam .

Miles
 

thefizz

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A little hint:
Don't discard your old fixer after a printing session. Discard it in the middle of the session, after test strips and work prints are done. This way you get fresh fixer for the final prints.

Sounds like good advice to me.
 
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wiggywag

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