Over fixing the negatives

[dancqu]

The Dilution Changes Now and Then

Ah, yes! I bought a 1l bottle yesterday and noticed the same thing,
but have a closer look and you'll see that this is for the 1+3 dilution,
even less diluted than the 1+4 they proposed until now.

I've a reference from 1981 pegging the dilution a 1:3. I just checked
Ilford's on line PDF dated 2002 which pegs the dilution at 1:4. And
now on the bottle you say 1:3.

I also noticed that the ingredients listed on the label have changed
somewhat. Older bottles listed sodium acetate, sulfite and bisulfite,
ammonium thiosufate and water. The new bottle has acetic acid,
sodium sulfite, water, ammonium thiosulfate.

It adds up to the same or very nearly the same fixer. The older
mix had as an acid component bisulfite. Sodium acetate is the
sodium salt of acidic acid and is alkaline. The newer mix has
the acid and counters it with the alkaline sodium sulfite.
Likely more of the sulfite is added. Both have the
same mix of ions although the blend may have
been modified some little.

Regarding how much time a print needs in the fixing bath,
follow the papers manufacturer's times for paper strength fixer
(for a rapid one), but do check with selenium toner to be sure.
There's no substitute for real evidence and FB prints can be
archival only if they're treated accordingly!

Paper Strength for paper. Film strength, which some use, was
a popularized Ilford invention from the early 1980s and the
fixer step of the Ilford Archival Sequence. The other steps
are a first wash, a protracted soak in wash aid, then
a second wash. All in all, the quickest way to
a clean print.

Ilford PDFs no longer make any mention of the sequence. They
do though still note a paper time for Film strength.

Two Bath: Ilford "... extremely efficient ..." Dan

 

[polyglot]

Again, here are the three main 'secrets' to get print longevity:

1. Fix as much as you need but as short as you can to get the non-image silver content below 0.008 g/m^2. (two-bath fixing works best)
2. Wash as long as you need to get below 0.015 g/m^2 of residual thiosulfate. (washing depends on diffusion, constant fresh water works best, because it prevents equilibrium)
3. Tone the print in selenium (or better sulfide) to convert metallic silver into more stable compounds.

There are effective tests to confirm 1 and 2 from whatever method you chose.

Thankyou for that. I take it the test for (1) is a drop of sulfide toner on a blank area. Is the test equally valid with other (eg thiocarbamide or selenium) toners? Does that test only for silver salts (insufficient fixing) or does it also reveal the presence of silver ions left behind by using overloaded fixer?

I get the impression that the silver-nitrate check for (2) isn't very sensitive. Do you need to do some under-washing tests, find the point where a stain appears and then double that or something?

Is there any issue with using Rapid Fix at 1+4 on paper for a while and then using it with film? I understand that archival processing of the paper requires very low ionic silver content but it seems that doesn't apply to film, so it should be reasonable to use fresh fixer on the paper as second-bath then as first-bath and then use it for film. I've heard that there are products washed out of film that make fixer unsuitable for archival processing of paper, but I'm going the other way. I ask because it's quite expensive (nearly $20/L) here.

And one more thing. People keep talking about long-term stability, the evils of residual silver and/or thiosulphate etc, but what sort of time-scale are we talking about here? A week? Year? Decade before changes are visible?

This article seems to suggest the 5 minute number applies to sodium thiosulphate (non-rapid) fixers and that one should follow 1-minute advice on the Rapid Fixer bottle (or better yet, 30s in each of two baths) for FB as that will minimise thiosulphate migrating into the paper. And he talks of two hour washes - which is practically a criminal offense here in AU with our water-use restrictions. Seriously, there are fines.

 

[RalphLambrecht]

...I take it the test for (1) is a drop of sulfide toner on a blank area. Is the test equally valid with other (eg thiocarbamide or selenium) toners? Does that test only for silver salts (insufficient fixing) or does it also reveal the presence of silver ions left behind by using overloaded fixer?...

Working strength sulfide toner work well. Selenium has also been suggested and I know that working strength paper developer works. I don't know about thiocarbamide toners. Partially fixed silver salts and exhausted fixer leave silver complexes that are harder to detect. Two-bath fixing minimizes the risc of that to happen.

...I get the impression that the silver-nitrate check for (2) isn't very sensitive. Do you need to do some under-washing tests, find the point where a stain appears and then double that or something?...

The ultimate test is the methylene-blue test, but it is not something for an amateur darkroom. I find HT-2 sufficiently sensitive, and even unnecessary if an archival washing procedure has been applied. 'Photographic Facts and Formulas' suggests and unnamed test, which is more sensitive than HT-2 but unfortunately depends on very toxic chemicals. I would stick to HT-2 and use it to verify the washing procedure employed.

...Is there any issue with using Rapid Fix at 1+4 on paper for a while and then using it with film? I understand that archival processing of the paper requires very low ionic silver content but it seems that doesn't apply to film, so it should be reasonable to use fresh fixer on the paper as second-bath then as first-bath and then use it for film. I've heard that there are products washed out of film that make fixer unsuitable for archival processing of paper, but I'm going the other way. I ask because it's quite expensive (nearly $20/L) here...

I'm not sure on that one, but it may depend on the paper. As far as I remember, bromide carry-over was the issue. This could affect film development and effective film speed. Since I'm using one-shot two-bath fixing for film, I don't have this issue. My film and paper fixers have the same strength, but they are never mixed.

...And one more thing. People keep talking about long-term stability, the evils of residual silver and/or thiosulphate etc, but what sort of time-scale are we talking about here? A week? Year? Decade before changes are visible?...

The numbers, I mentioned in my post are roughly aiming for a life expectancy of 100 years plus (LE100). The ISO standard publishes numbers for LE100 and LE500, but with film, substrate longevity becomes an issue. Roll films are coated on acetate substrate, which is limited to 50-100 years. Sheet film is coated on polyester, which is expected to last 500 years or more. With glass plates, only the LE of the emulsion itself is an issue. This all assumes optimal environmental conditions, most of which are beyond normal control. I think is is reasonable to aim for 100 years. The issue of longevity is also influenced by the size of the silver grain in the emulsion (surface-to-volume ratio). The smaller the grain size, the less residual chemicals are permitted. Since paper grain is smaller than film grain, paper washing, for example, is more critical than film washing.

...This article seems to suggest the 5 minute number applies to sodium thiosulphate (non-rapid) fixers and that one should follow 1-minute advice on the Rapid Fixer bottle (or better yet, 30s in each of two baths) for FB as that will minimise thiosulphate migrating into the paper. And he talks of two hour washes - which is practically a criminal offense here in AU with our water-use restrictions...

The advise to wash FB papers as short as possible in film-strength fixer is solid. 30s twice might be a theoretical minimum, but may lead to uneven fixing. I believe that 1 minute fixing is a reasonable minimum for each bath. But again, it depends on the paper, and a proper test is a must.

Without HCA it will take 2 hours or more to get to archival thiosulfate levels, but extended washing has its own set of problems. I suggest a brief rinse after fixing, followed by a hypo-clearing bath and a 30 minute washing slowly running water, assuming the wash water is at 20C. Double this time for colder water and avoid temperatures below 10C. Also, hard water is better than soft water. Water softeners may be good for your pipes but not for print washing.

 

[polyglot]

Most informative, thankyou Ralph. I'm still not sure though how bromide carried over from paper in old fixer would effect film development or effective speed given that development has ceased before the possibly-polluted fixer hits the film. I thought bromide could inhibit development, not undo it, or am I mistaken there?

 

[RalphLambrecht]

Most informative, thankyou Ralph. I'm still not sure though how bromide carried over from paper in old fixer would effect film development or effective speed given that development has ceased before the possibly-polluted fixer hits the film. I thought bromide could inhibit development, not undo it, or am I mistaken there?

I think you are correct. As I said, I don't mix film and paper fixer. I know, used film fixer should not be used for paper, but I'm not sure if the same is true the other way around. If money was tight, I would probably risk using used paper fixer for the 1st film fix and use fresh fixer for the 2nd fix, but I have never tried or tested this.

 

[fschifano]

That may be safe from a chemistry standpoint, but paper fixer picks up an awful lot of detritus from the paper itself and from being out in open trays. I'd be careful of that. It's one thing for a tiny bit of dust, lint, or whatever to get stuck on a print. It is quite something else if that same piece of detritus gets stuck to the emulsion of the film and dries there. It may never come off without damaging the negative.

 

[RalphLambrecht]

That may be safe from a chemistry standpoint, but paper fixer picks up an awful lot of detritus from the paper itself and from being out in open trays. I'd be careful of that. It's one thing for a tiny bit of dust, lint, or whatever to get stuck on a print. It is quite something else if that same piece of detritus gets stuck to the emulsion of the film and dries there. It may never come off without damaging the negative.

That's a good point!

 

[Martin Aislabie]

I always filter the chemicals I intend to re-use both out of the bottle and back in again at the end of each session.

Its amazing the crud the otherwise clean looking solutions pick up along the way

Martin

 

[hoffy]

Wow, very good information here. I see some serious changes to the way I do things at home, as I use the same fixer on both film and paper.

Cheers

 

[polyglot]

I did a batch of prints today (Kentmere FB) and found that 2x45s in 1+4 RF was quite enough - absolutely no mark on blank paper if I left developer on it for 5 mins in light after fix+rinse. Didn't try 2x30s though. I don't have HT-2 (silver nitrate) yet.

Edit: I use coffee filters on my fixer before it gets near the film. I don't have any problems with dust or hair dried on my emulsions.

 

[Puma]

How will over fixing affect film?

I use RAPID fixer without hardener in a TWO bath system, each bath for 7.5 (15 total) minutes agitating for thirty seconds out of each minute. I'm probably going to far and can easily test to find the perfect time but I've got a whole string of tests that I did this way and want to know if my results were skewed by excessive fixing? I don't care if they aren't archival, my main concern is the effect on the highlight and shadow densities with TMY-2.

I did this out of frustration with less than adequate fixing with Kodak's recommended time and because I want a crystal clear film base. Am I hurting anything?

Sincere thanks for your reply,

Puma

 

[BetterSense]

I don't think you are hurting anything. I use 2-bath Ilford rapid fixer, at least 5 minutes in each bath, but sometimes a lot more. I like my TMAX to come out clear.

 

[polyglot]

With TMY2, 15 minutes is probably fine though I find that 8-10 minutes is about right. With some other films that clear in 1:00, 15:00 would be going too far IMHO and you should expect bleaching. Since you've invested a bunch of time in testing, you could perhaps do one more test comparing TMY2 frames fixed for 8:00 and 15:00.

The film doesn't need to be in fixer to get rid of the pink, you can do it in normal wash water or hypo clearing agent.

 

[RalphLambrecht]

How will over fixing affect film? ...

The attached graph is for paper, but the effect is similar to film.

As you can see, dense areas are more affected than areas poor in silver. This will reduce negative contrast a bit.

Maybe it's a cure for overdeveloped negatives.

 

[Puma]

Ralph,

This is exactly the kind of information that I was looking for! My tests are solid frames of zone VII density so now I know I don't have to repeat them. Now I can move on to finding expansion and contractions. Thank you very much for providing this. I'd buy your book just based on a chart like this, I love solid factual information.

Cheers,

Puma

 

[Gerald C Koch]

Edit: I use coffee filters on my fixer before it gets near the film. I don't have any problems with dust or hair dried on my emulsions.

Using coffee filters is a bit problematic. Some brands are better than others. Remember they are designed for rapid filtration of large particles (coffee grounds). Some finer particles may just go throuh them. Chemex brand filters for their coffee brewing system are much better since they are made from lab grade filter paper and will trap finer particles.