Advise: single bath fixing for fiber paper? Bad idea?

Doremus Scudder said:

The best product (Ag-fix test strips) I have seen has a threshold sensitivity of 0.5g/l of dissolved silver.

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Doremus Scudder said:

If there is a better convenient method to monitor silver concentration in a fixing bath that is more sensitive, I would really love to hear about it!

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I have described previously on APUG a method once published by Kodak as a possible alternate method. It used the Kodak silver-estimating papers, which look like the Johnson's brand. The main problem is that you have to make your own calibration curve, and use a densitometer to read it. Basically you suspend the test strip, motionless, in a small cup of the sample, for 30 seconds. Then briefly rinse and dry the strip, then read a "blue filter" reflection density. You look it up on your self-made calibration curve to get the concentration. We found it pretty reliable from about 0.1 g/L to maybe 1. 3 g/L, with results reliably within 0.1 g/L.

This was the only "adequate" method we ever found after trying a number of abbreviated tests. (Eventually we equipped our lab with a good instrument (AA spectro unit), but occasionally continued to use the dip test for quick screening)

RalphLambrecht said:

Doremus ,your ag fix test strips are a great way to test for silver content;I use them all the time with two-bath fixing to determine when to discard the first bath.

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Ralph, I find the strips really useful for what you suggest: testing bath one of a two-bath regime. There, the dissolved silver can get fairly high. I like to toss mine when it reaches 2g/l or before. However, I wouldn't trust them to give me a reliable reading at 0.5g/l since this is the limit of the sensitivity. Plus, there's no way to see how close to 0.5g/l you are getting before you are suddenly there (or over...).

Mr Bill said:

I have described previously on APUG a method once published by Kodak as a possible alternate method. It used the Kodak silver-estimating papers, which look like the Johnson's brand. The main problem is that you have to make your own calibration curve, and use a densitometer to read it. Basically you suspend the test strip, motionless, in a small cup of the sample, for 30 seconds. Then briefly rinse and dry the strip, then read a "blue filter" reflection density. You look it up on your self-made calibration curve to get the concentration. We found it pretty reliable from about 0.1 g/L to maybe 1. 3 g/L, with results reliably within 0.1 g/L.

This was the only "adequate" method we ever found after trying a number of abbreviated tests. (Eventually we equipped our lab with a good instrument (AA spectro unit), but occasionally continued to use the dip test for quick screening)

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Mr Bill, You've made my case that there is no really convenient way currently available to test for dissolved silver at the levels you need for one-bath fixing

Seriously, if I had a densitometer, I might get some silver-estimating papers and try it out. However, the devil seems to be in the calibration. I'd have to come up with a way to dissolve silver compounds that the papers are sensitive to in the right amounts to accurately get control solutions... I'll refer you to the first sentence.

Best,

Doremus

The fixer topic gives me serious headaches. I mix almost all of chemicals from raw ingredients, with the notable exception of Rodinal and fixer. I'd love to make my own fixer too. I'm just not sure how and which. ATS is expensive over here. I can get the premium rapid fixer stock solution (RXN, X89) way way cheaper than the amount of 60% ATS solution required to make 1L of working solution on my own. Sodium Thiosulfate is cheaper though and 1L working solution would cost me about the same than the liquid neutral rapid fix (if I'd buy the crystals and sulfite in 25kg sacks).

As I see it there are two viable options, not counting the economical benefits of 2-bath fixing, silver recovery etc. which are not really relevant for my home darkroom (my throughput is not high and I don't want to keep the fix after the session):

1) Lightning fast fixing (1minute) in a single bath in near neutral rapid fixer for short washing times, HCA optional, etc.
2) Fixing time is not critical (>1min). HCA step is a must then anyways and there's no benefit in fixing quickly except getting to the next sheet faster. I could imaging using those semi-versions like OF-1 just to save some time.

So is there anything which would speak against using a home made Sodium Thiosulfate fix for modern FB papers with the single-bath method and a throughput of say 10 8x10s per liter and still be archival?

Concerning the 2-bath method. To me it only makes sense then when my fixing times are not critical. I seriously can't get a sheet of 12x16 paper through 2 baths in one minute total. To drain the sheet already takes 20-30seconds. It might make much more sense with Sodiumthiosulfate fixers when the fixing is split over time. Like 4minutes first fix and 6 minutes at the end of the session.

Am I oversimplify things? Did I mention the fixer topic gives me headaches...

Cheers,
Andi

PS: my ideal fixer would be:
- self mixed
- ingredients < 10 Euros per 1L stock
- fixes a sheet of 12x16 FB in one minute
- archival up to 20 sheets of 8x10 in single-bath keeping the 1min time
- odourless
- near neutral
- hardener addable if required
- working solution keeps up to 3month (unused)
- stock solution (to be diluted 1+4) keeps up to 6months

~andi said:

...
PS: my ideal fixer would be:
- self mixed
- ingredients < 10 Euros per 1L stock
- fixes a sheet of 12x16 FB in one minute
- archival up to 20 sheets of 8x10 in single-bath keeping the 1min time
- odourless
- near neutral
- hardener addable if required
- working solution keeps up to 3month (unused)
- stock solution (to be diluted 1+4) keeps up to 6months

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It seems like Ilford Hypam or Rapid Fixer off the shelf will almost suffice for your needs. It's almost neutral pH and at the 1+4 dilution will fix your FB paper in 1 minute. However, you'll only get 10 8x10s per liter if you want to fix for optimum permanence. Price may be more than €10/liter of stock, but still, one liter of stock diluted 1+4 makes five liters of working solution, which is still pretty economical, in the neighborhood of €2-3 for a liter of working solution.

Best,

Doremus

Hi Doremus,

yes the Ilford fixer works. So does Amaloco X89 or Rollei RXN which I am currently using (they're even cheaper to get here than the Ilford, can't add hardener but that I very rarely need anyways). I'm rather happy with them too. The one drawback remains: not self-mixed (from raw chemicals I mean). In the end, after agonizing research for a couple of days, I'll probably will just stick to the commercial product. Has happened before, probably will happen again (once in a while it bugs me having to buy the ready made fixer

Cheerio
Andi

I highly recommend to OP to read the manual first.
http://www.ilfordphoto.com/Webfiles/2006130218312091.pdf

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 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.

Slixtiesix said:

I also see that I forgot something important: 10-12 8x10 prints in 1l of working solution of course. Without that, the whole recommendation would be pointless.

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It is also seems to be pointless and wrong after reading of the same:
http://www.ilfordphoto.com/Webfiles/2006130218312091.pdf

Capacity without replenishment.
Material Dilution Capacity 1 litre of working strength fixer:
RC paper 1+4 or 1+9 - 80 sheets 20.3x25.4cm (8x10in).
FB paper 1+4 or 1+9 40 sheets 20.3x25.4cm (8x10in).

The figures for paper may be exceeded whenever print stability is not critically important.

Material Dilution Time (minutes):
1+4 RC paper 1/2 minute
1+9 RC paper 1 minute
1+9 FB paper 2 minutes
1+4 FB paper 1 minute

Ko.Fe. said:

I highly recommend to OP to read the manual first.
http://www.ilfordphoto.com/Webfiles/2006130218312091.pdf

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 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.



It is also seems to be pointless and wrong after reading of the same:
http://www.ilfordphoto.com/Webfiles/2006130218312091.pdf

Capacity without replenishment.
Material Dilution Capacity 1 litre of working strength fixer:
RC paper 1+4 or 1+9 - 80 sheets 20.3x25.4cm (8x10in).
FB paper 1+4 or 1+9 40 sheets 20.3x25.4cm (8x10in).

The figures for paper may be exceeded whenever print stability is not critically important.

Material Dilution Time (minutes):
1+4 RC paper 1/2 minute
1+9 RC paper 1 minute
1+9 FB paper 2 minutes
1+4 FB paper 1 minute

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The 10-12 print number is correct for optimum archival stability.

I use a 1 bath fix, but I dispose of it after every session. I rarely make it to 20 prints either. Fix is pretty cheap when you do the math on it. A lot cheaper than paper. If I was making big prints and had the space, I would use two baths for economy. I usually just print 8x10 though so a one bath/one use works fine for me since I am not using a lot of volume. I also do a long soak for washing, usually overnight since I typically print at night. I tone my prints and have never had a problem with staining doing it this way.

Patrick Robert James said:

The 10-12 print number is correct for optimum archival stability.

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It is not in the document for the most common fixer. Or did I missed it? From where it comes from? Homemade soup recipe?

Ko.Fe. said:

It is not in the document for the most common fixer. Or did I missed it? From where it comes from? Homemade soup recipe?

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Page 4, 2nd column, 1st paragraph, last sentence:
"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."

spijker said:

Page 4, 2nd column, 1st paragraph, last sentence:
"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."

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Thanks! I'm the one who needs to read manual ten times.

Single tray is like washing your car with dirty water.

If you are really cramped for space, have an extra tray, or at end of printing session, refix them all in fresh fix.

I believe washing is shortened if you use two bath, but check. The longer paper soaks in fix, the long the wash required. two bath is just 60 sec in each, very fast.

Ronald Moravec said:

Single tray is like washing your car with dirty water.

If you are really cramped for space, have an extra tray, or at end of printing session, refix them all in fresh fix.

I believe washing is shortened if you use two bath, but check. The longer paper soaks in fix, the long the wash required. two bath is just 60 sec in each, very fast.

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I believe washing time is reduced by half with a rapid fix, as the print is fixed for only 1 minute, followed by HCA. Less wash water is required...especially if you use Ilford's method. I learnt single bath rapid fix while living in Japan. I had very limited space in my closet-sized darkroom.

The use of a single fixing bath with FB papers IS a bad idea. Much better to use the two bath system and also more economical. Really doesn't matter whether you use rapid fix or not. The same idea applies. That is to lower the silver content to archival levels.

I thought the washing time is shortened significantly only with a short time in fix <=1minute, anything over 60s prolongs washing time tremendously to 60mins+ or so (believe I read this in Ralphs book). Another problem is the acidity of many rapid fixers which makes the paper fibers shrink and it becomes harder to wash byproducts out. With acid fixer you need HCA to soften the fibers again. In any case, you wash for 60mins to be at an optimum unless you fix for 45seconds only. I'd say that's quite a challenge with a 2-bath fix.

With SodiumT fixer you have to fix long (like 8 minutes total or so), super-quick-washing bye bye. But it's usually a neutral fix and HCA is not really necessary. At any rate you wash for 60mins as well.

The two bath method, as far as I understand, came from the fact that SodiumT fixer has not as much capacity as AmmoniumT fixer. So in a high throughput situation, to make certain you've fixed properly, the two bath method was applied (plus the econmical benefits).

The 10 sheets of 8x10 btw. is also mentioned in the Darkroom Cookbook. It seems to be the "safe-side" figure with all fixers.

At least that's my understanding so far. Also, there is a french publication which found that shortening the wash time to 45mins works if you use a 2-stage wash (running water first, then dump and refill):

http://www.plastique-deville.com/files/laveur_a_epreuves_cartoline.pdf (page 2)

I'm no chemist, but wouldn't it be possible to wash a car perfectly clean with dirty water if there are enough tensides left in it to bind the dirt?

Ciao,
~andi

I use 2 bath even with Rapid. 60 sec per if I remember, 2 min wash, HCA, archival finish wash

Ronald, that's what I've been using too. Except for RC and 5x7 proofs. I never manage the 30+30 seconds though, its always longer. Therefore I'm using the HCA too, then 15min running water wash, then 60mins dump and refill (about 6 times). HT-2 checks out fine. So I'm wondering if I should switch to a fixer like OF-1 as I can mix it myself and it's rapid enough. Hell, I'm probably just going to try it on a rainy day...

Cheers
Andi

For 20x24 prints, I plan to use one bath of fixer only as the tray takes at least 4 liters of fixer. 10 prints including test strips per 4 litres of fresh fixer is perfectly archival. When I make numerous 5x7 FB pints from 35mm film, I use two baths of fixer

Thanks to everyone with the great responses. I learned a great deal.

Doremus Scudder said:

A couple of general comments/observations.

First, two-bath fixing is way more economical; by a factor of 3-4. According to Ilford, throughput for "optimum permanence" should be 10 8x10-inch prints per liter of fixer. This assumes a dissolved silver content in the fix of 0.5g/l. Using their "commercial" standard of 2g/l extends the capacity to ~40 8x10s per liter of fix. Ralph's 1g/l recommendation would be somewhere in between.

I have no idea how you plan to monitor your fixer for dissolved silver. The best product (Ag-fix test strips) I have seen has a threshold sensitivity of 0.5g/l of dissolved silver. The "HypoCheck" drops are nowhere near that sensitive. That means that even with the best test strips, you are testing on the border of the test's sensitivity. Any margin of error there (and there surely is) could/would lead to overusing the fixer slightly. That's likely pretty good, but not as good as two-bath fixing where the second bath can be allowed to reach 5g/l. If there is a better convenient method to monitor silver concentration in a fixing bath that is more sensitive, I would really love to hear about it!

A second fix does not have to follow the first fix immediately. You can collect prints in a holding bath and give them the second fix at the end of the session in tray.

Single-bath fixing has little room for error; two-bath fixing has a built-in safety factor, especially if one underuses the first bath a bit.

Ilford document: http://www.ilfordphoto.com/Webfiles/2006130218312091.pdf -- See p. 4 for the section on silver concentration.
Ag-fix test strips: http://www.mn-net.com/tabid/10488/default.aspx

Best,

Doremus

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Where/who sells these strips? I would also like to buy some decent pH test strips. 30 years ago when I worked as a "chemist" we used pH strips made by EM Science (Germany). I have some water hardness strips stockpiled in the freezer that work great too.
Mike

mshchem said:

Where/who sells these strips? I would also like to buy some decent pH test strips. 30 years ago when I worked as a "chemist" we used pH strips made by EM Science (Germany). I have some water hardness strips stockpiled in the freezer that work great too.
Mike

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Just search for "AG-Fix test strips" and pick a vendor that suits you. You can get them from Amazon or from numerous scientific supply houses.

Doremus

For those suggesting doing the 2nd fix at the end of a print session, how long do you then rewash the prints for? Another hour? Thanks.

As a rule of thumb, yes, an hour in an archival washer with running water preceded by HCA and you should be on the safe side. Nothing beats testing though, the silvernitrate test (aka HT-2) is cheap, reliable and quick (cp. http://unblinkingeye.com/Articles/Archival/archival.html).

Also have a look at this delightfully succinct thread, it sums up most important things concerning washing (including links to "Mysteries of the Vortex" which is probably the most comprehensive non-scientific paper about washing):

(there was a url link here which no longer exists)

What are you guys thoughts on two bath fixing using hypam at 1:9? That's what I've been doing lately. One full minute in each bath. Then hypo clear for 5 minutes, wash for an hour.

~andi said:

As a rule of thumb, yes, an hour in an archival washer with running water preceded by HCA and you should be on the safe side. Nothing beats testing though, the silvernitrate test (aka HT-2) is cheap, reliable and quick (cp. http://unblinkingeye.com/Articles/Archival/archival.html).

Also have a look at this delightfully succinct thread, it sums up most important things concerning washing (including links to "Mysteries of the Vortex" which is probably the most comprehensive non-scientific paper about washing):

(there was a url link here which no longer exists)

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Thanks andi. I'm reading the linked items. I've been a little lazy to date. Single fix, two trays for washing and more frequent replacement of the fix (1:4 Hypam)

I've just started investigating a 'proper' print washer as for now I just put the single fixed prints in Tray 1 of water for a minute of agitation, then into Tray 2 of water with a hose running constantly but I might be better served switching one of those trays for a second of fix and then getting some kind of improved print washer (or refix at end of session then into print washer.)

I'll read more and consider before buying anything. The RC paper (horizontal tray) print washers are considerably cheaper than (vertical, finned) fiber ones, so I'm also still pondering on if I really need a dedicated print washer (for 8x10, 7x5)