Two bath fix question

I would like to ask something about two bath fixing. I use Moersch Alkaline fixer (1+5). I send him an email about capacity for fiber and he answered me this.

Dear Jesse, 1+5 1 liter works for at least 2 square meters. With a two bath fixing 1+1 liter you may use it for 4 square meters or more.

It is depending on the white borders you have, the more white, the faster the fixer is "full" of silver.

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Now I have a few questions.

Question 1. By using a two bath fix method, the capacity doubles. But do I discard both baths after 4 square meters or keep the second bath as first bath? Because the second bath isn't "fresh" anymore, it has less capacity right, or how does it work?

Question 2. I currently used about 3,00m² with a 2+2 liter two bath setup. Can I go to 8m² then? Also see question 1.

Question 3. If the limit is reached, is the first bath filled with 2 Ag (silver) / liter? And what about the second bath?

Currently I'm printing exhibition photos (my first exhibition). And they don't need to be really archival, but professional grade..

Many thanks

In answer to your Question 1 - NO, the capacity does not double due to using two bath fixing. Mr.Moersch suggested using a more concentrated fixer (as does Ilford) and the apparent increase in capacity is due to that reason. 'Archival' two bath fixing does not increase capacity - it increases completeness of fixing by means of having a 'fresher' second bath.

For Question 2 - what do you mean by "2+2" fixing? is that a typo?

For Question 3 - what does "2 Ag (silver) / liter" mean?

EDIT: All my answers are rubbish. My apologies, put it down to a much too long working night.

Jessestr said:

Question 1. By using a two bath fix method, the capacity doubles. But do I discard both baths after 4 square meters or keep the second bath as first bath? Because the second bath isn't "fresh" anymore, it has less capacity right, or how does it work?

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The apparent capacity increases for two reasons: First, you are using twice as much fixer. The capacity in throughput is for the volume of the first bath only. With one-bath fixing, you would only have this bath, but with two-bath fixing you have another bath of equal volume. Second, it is a question of the amount of retained silver and to what standard you fix. Keep in mind that a liter of your fix (I'm basing this on Ilford's recommendations) will fix about 40 8x10-inch prints to "commercial standard" but only 10 8x10-inch prints to "optimal permanence" standard. This smaller last number is due to the amount of dissolved silver in the fixer, which inhibits full fixing after a very short while. With two-bath fixing, the second bath remains fresher (i.e., very little dissolved silver) much longer, thus almost doubling the effective capacity of the entire process. Thus I can get about 35 8x10 prints processed to "optimal permanence" from a two-bath set up of 1 liter first bath and 1 liter second bath.

Jessestr said:

Question 2. I currently have used about 3,00m² with a 2+2 liter two-bath setup. Can I go to 8m² then? Also see question 1.

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Moersch says 4 sq. meters for a 1+1 liter two-bath fixing regime (1 liter first bath; 1 liter second bath for the poster who didn't understand the shorthand). Doubling the size of both baths will double the capacity (however, I'd still likely not fix to total capacity, leaving a little safety factor). So, yes, you can go to 8 sq. meters provided that (and this is very important) the fixer has not gone bad from oxidation. Length of storage is important. Lifespan of fixer in open trays is only 7 days. In a half-full tightly-stoppered bottle about 6 weeks. Again, I wouldn't even come close to approaching these extremes before I discarded the fixer.

Jessestr said:

Question 3. If the limit is reached, is the first bath filled with 2 Ag (silver) / liter? And what about the second bath?

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When the capacity is reached, the first bath is at or close to its limit. It is discarded (appropriately, of course; best if it's turned in for silver recovery) and the secondn bath becomes the new first bath (it is still relatively little used). A new second bath is mixed. This procedure can go through seven cycles according to Kodak; again, I wouldn't take it this far myself. And, just FYI, the dissolved silver in the fixer is in the form of complex silver-thiosulfate compounds, not molecular silver.

Best,

Doremus

For modern papers you may never need the second bath. This is something I have read from a post written by PE.

Jessestr said:

I would like to ask something about two bath fixing. I use Moersch Alkaline fixer (1+5). I send him an email about capacity for fiber and he answered me this.



Now I have a few questions.

Question 1. By using a two bath fix method, the capacity doubles. But do I discard both baths after 4 square meters or keep the second bath as first bath? Because the second bath isn't "fresh" anymore, it has less capacity right, or how does it work?

Question 2. I currently used about 3,00m² with a 2+2 liter two bath setup. Can I go to 8m² then? Also see question 1.

Question 3. If the limit is reached, is the first bath filled with 2 Ag (silver) / liter? And what about the second bath?

Currently I'm printing exhibition photos (my first exhibition). And they don't need to be really archival, but professional grade..

Many thanks

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keep the 2nd bath as the 1st bath and mix a fresh 2ndbath for the next session.

What I miss in all descriptions of the 2 fix bath method that I've read is when the 1st bath is discarded and the 2nd bath becomes the 1st bath, how does one determine the remaining capacity of the new 1st bath?

Thanks for the answers.

spijker said:

What I miss in all descriptions of the 2 fix bath method that I've read is when the 1st bath is discarded and the 2nd bath becomes the 1st bath, how does one determine the remaining capacity of the new 1st bath?

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Exactly.

Very little silver makes its way into the second bath. So when you switch that second bath to the first bath, you can treat it as being as "fresh" as unused fixer, at least with respect to capacity calculations.

I think it's obvious. Your 1st bath is the one that has reached its capacity by the time you replace it with the 2nd bath.

So when talking about capacity, I think you're really talking about the capacity of the first bath even though your action is to replace the 2nd bath.

Also keep the time frame in mind. I believe it is good practice to discard both (any) bath after 2 weeks. Is it 2 weeks?

When printing an exhibition, you might get the cycle going for seven passes, but as a casual printer... I never get that far.

Time runs out on my fixer bath before capacity.

p.s. I work for Kodak but the positions I take and opinions I express are my own and not necessarily those of EKC

MattKing said:

Very little silver makes its way into the second bath. So when you switch that second bath to the first bath, you can treat it as being as "fresh" as unused fixer, at least with respect to capacity calculations.

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First the hypo is not to a first order doing any thing to the silver it is instead making the silver halides into a soluble series of compounds.

Yes it would attack the silver image if you left a print in for aeons.

Second the load on the second bath is dependent on the time you keep the print(s) in the first bath as well as the number of prints.

Maxing out the first bath defeats the object of the two bath process.

You might as well use a series of first baths.

The two bath process is an archival process it is not for extracting the most prints from a given amount of hypo.

So you replace the first bath early and promote the 2nd bath.

And put fewer prints through the new first bath, than you put through the first first bath.

Your process may be different. That is what I was taught.

OP

you can do the clip test
and monitor your fixer that way
if it is the 2nd bath rotated to #1 you will
have the fresh fixer baseline,
so it is just a matter of 2x that original #

good luck with your exhibit !
john

Doremus Scudder said:

The apparent capacity increases for two reasons: First, you are using twice as much fixer. The capacity in throughput is for the volume of the first bath only. With one-bath fixing, you would only have this bath, but with two-bath fixing you have another bath of equal volume. Second, it is a question of the amount of retained silver and to what standard you fix. Keep in mind that a liter of your fix (I'm basing this on Ilford's recommendations) will fix about 40 8x10-inch prints to "commercial standard" but only 10 8x10-inch prints to "optimal permanence" standard. This smaller last number is due to the amount of dissolved silver in the fixer, which inhibits full fixing after a very short while. With two-bath fixing, the second bath remains fresher (i.e., very little dissolved silver) much longer, thus almost doubling the effective capacity of the entire process. Thus I can get about 35 8x10 prints processed to "optimal permanence" from a two-bath set up of 1 liter first bath and 1 liter second bath.



Moersch says 4 sq. meters for a 1+1 liter two-bath fixing regime (1 liter first bath; 1 liter second bath for the poster who didn't understand the shorthand). Doubling the size of both baths will double the capacity (however, I'd still likely not fix to total capacity, leaving a little safety factor). So, yes, you can go to 8 sq. meters provided that (and this is very important) the fixer has not gone bad from oxidation. Length of storage is important. Lifespan of fixer in open trays is only 7 days. In a half-full tightly-stoppered bottle about 6 weeks. Again, I wouldn't even come close to approaching these extremes before I discarded the fixer.



When the capacity is reached, the first bath is at or close to its limit. It is discarded (appropriately, of course; best if it's turned in for silver recovery) and the secondn bath becomes the new first bath (it is still relatively little used). A new second bath is mixed. This procedure can go through seven cycles according to Kodak; again, I wouldn't take it this far myself. And, just FYI, the dissolved silver in the fixer is in the form of complex silver-thiosulfate compounds, not molecular silver.

Best,

Doremus

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So I could get 8 square meters, but to be safe. I only go up to 7 to get optimal permanence?
That is an awful lot of paper... I like that So I can probably print up 5 more 30x40s before I'm at 7 square meters... This is long lasting stuff...

I develop every day but I do not leave them in open trays, I always store them back in bottles and clean everything so it doesn't become messy..

The "clip test" mentioned above is for film - as i understand it, film and paper do different things to fixer and you shouldn't test one for the other.

I've never done 2-bath fixing - but I do test my fixer through a session and I've found it lasts much longer than the instructions state.

To test your fix: under safelight, take a small strip of the paper you're using that day, and mark off several 1" lines, 4 or 5. Soak the strip in water for a minute or so, and then dip it in the fix with a timer going. Dip to the first line for say, 15 seconds.. then the second, and so on. If you have 4 lines, you'll have fixed the paper for 15, 30, 45, and 60 seconds as you dip it further into the fix. Rinse it and turn on the lights. Expose the paper to light for a few seconds, and develop it. If, say, the 15 second-fixed area is gray, the 30 has a hint of gray, and the 45 is white, you'll know your fix - in its current state - was able to fix that particular paper in 45 seconds. Double this time to be safe. That's worked well for me, it's the method described in "Way Beyond Monochrome" and I actually learned it here on APUG.

baachitraka said:

For modern papers you may never need the second bath. This is something I have read from a post written by PE.

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I can hardly believe this is true.

I am try to dig his post but not successful. He said modern papers are different and may never require the second bath.

miha said:

I can hardly believe this is true.

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No, baachitraka is quite right, PE has written (quite recently) that he considers 2-bath to be unnecessary for complete fixing.
(there was a url link here which no longer exists)
(there was a url link here which no longer exists)


Of course, others not as eminent disagree.

I should learn to bookmark important things in life. Thanks @pdeeh

There are several other discussions and in those some emphasis on higher concentration and short fixing times. i.e., Fix for less than 60seconds.

pdeeh said:

Of course, others not as eminent disagree.

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Like Ilford, for instance?

http://www.ilfordphoto.com/Webfiles/200621111117720.pdf

Principles of good fixation (from above, page 3):

1. Fix only a few prints before replacing the fixing bath...
2. Use two-bath fixation
3. Use a single fixing bath plus a wash aid...

It has little to do with the paper, but rather a preferred method of fixing. There's no reason why a single-bath fixing regime won't work and work extremely well. It's simply a matter of not exceeding the capacity in terms of dissolved silver content appropriate to the standard you wish to fix to. For "optimum permanence" Ilford recommends: " For prints that need maximum stability for long term storage a the maximum silver level in the fixer should not rise above 0.5 g/l i.e., approximately 10 20.3 x 25.4cm (8 x 10in) prints." If I remember correctly, Kodak recommended even less, 0.2g/l. FWIW, Ilford states that "if a high level of image permanence is required for commercial use the silver concentration in the fixer should be kept below 2 g/l when fixing FB papers. This approximates to 40, 20.3 x 25.4 cm, (8 x 10 inch) FB prints." It's up to you which standard you fix your prints to. With a two-bath regime you don't have to change fix as much and can get a bit more out of the first bath, since the second bath makes up for the exhaustion in the first somewhat. However, using a single bath and staying within capacity results in just as well-fixed prints.

For Xmas: Yes, the fixer changes silver halides into soluble compounds. Some of this gets into the fixer. The amount of these dissolved silver compounds in the fix is one of the determiners of how thoroughly the fixer can do its job. Too much silver in the fix and the fixer will no longer completely change the silver halides into easily soluble compounds; rather some of the silver remains in intermediate states in the chain of reactions that lead from insoluble to soluble. For "general purpose" or "commercial use" standards, having some of these retained compounds is accepted. For "optimum permanence" it isn't. Hence the differing capacities above for different standards. By doing the first half of the fixing in the first bath and draining well before transferring keeps the second bath fresh enough that it can be used as the first bath at the same capacity for seven cycles (according to Kodak, whose research I trust). Only then is there enough build-up of carried over compounds to warrant mixing both baths fresh. I, personally, never go through nearly that many cycles before mixing fresh baths.

So, one-bath or two-bath? A question of workflow and preference. How well you wish to fix your prints? Also a matter of preference to some extent. While modern papers may or may not have more silver halides in them than older papers, you could always adequately fix papers with just a single bath. What would change with differences in the silver content of papers would be the capacity of the fixer. That's still true today to some extent and, more importantly, throughput is just a guideline for capacity in any case. More white in a print means more undeveloped silver halide to fix out. All this is why serious workers use retained silver tests to check their fixing. Search here for the Kodak ST-1 test or for how to use selenium toner as a check for retained silver if you're interested.

Best,

Doremus

miha said:

like Ilford for instance?

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Not at all Ilford. In fact Ilford's own recommendation for archival permanence is single bath fixing in a 1+4 solution of rapid fixer for a short period (c.60s).

This is documented by Ilford in any number of their publications and technical information sheets.

pdeeh said:

Not at all Ilford. In fact Ilford's own recommendation for archival permanence is single bath fixing in a 1+4 solution of rapid fixer for a short period (c.60s).

This is documented by Ilford in any number of their publications and technical information sheets.

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True if you only fix a few prints before replacing the fixing bath.

This link offers a comprehensive read on fixing:

http://photo.net/black-and-white-photo-film-processing-forum/007dXZ

pdeeh said:

Not at all Ilford. In fact Ilford's own recommendation for archival permanence is single bath fixing in a 1+4 solution of rapid fixer for a short period (c.60s).

This is documented by Ilford in any number of their publications and technical information sheets.

Click to expand...

From the Ilford technical publication on Ilford Rapid Fixer:

"Two bath fixing
An extremely efficient method of fixing film or paper is to use the two bath fixing technique. Make up two separate fixing baths of the same solution volume. Fix the film or paper in the first bath for half the recommended fixing time and then transfer them to the second bath for the remainder of the time. Continue to work this way
until the capacity of the first bath is reached, then discarded [sic] it and replace it with the second fixer bath. Prepare and use a completely fresh second bath. Repeat this process as required with the result that the film or paper is always thoroughly fixed by the relatively fresh fixer in the second bath."

Here's a quote from the Ilford publication on Processing Black & White Papers:

"Two-bath fixing
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 (8x10inch) prints per litre/US quart 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."

Two things to note: First, Ilford claims an increase in capacity (my emphasis above) when using a two-bath regime. Second, Ilford recommends only four replacement cycles instead of the seven recommended by Kodak.

Ilford mentions only "Fixing" in their sequence for optimum permanence, not whether a one- or two-bath regime should be used. A two-bath workflow with their sequence should work just fine and, according to them, increase the capacity of the fix from 10 8x10s to 40 8x10s through the first bath.

Best,

Doremus

miha said:

This link offers a comprehensive read on fixing:

http://photo.net/black-and-white-photo-film-processing-forum/007dXZ

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Well worth expending the effort to read and understand this if you're interested in really knowing about fixation. I found this article years ago and it cleared up much confusion. That and the subsequent discussions with PE gave me an insight into the complexities concerning fixers and fixation.

Bottom line is: test, test, test to make sure your individual fixing regime is doing its job. No one else can really do that for you. I lieu of that, read carefully and follow the manufacturer's directions.

Best,

Doremus

http://www.film-and-darkroom-user.org.uk/forum/showthread.php?t=296
http://www.film-and-darkroom-user.org.uk/forum/showthread.php?t=344