Chrome alum vs hardening fixer?

avandesande · Jan 1, 2006

I have been using efke films and would like to harden the emulsion a bit. I know some people have recommended chrome alum stop bath, but I like to keep things simple and just use rapid fixer with hardener. How much better does the chrome alum work than hardening fixer?

Tom Hoskinson · Jan 1, 2006

I shoot and process a lot of Efke 100 and Efke 25 in LF sheet and roll film. I have seen no need to use either a hardening stop bath or a hardening fixer. IMO, emulsion damage with these films is caused by lack of proper handling discipline.

My fixer of choice for these films is a non-hardening Ammonium Thiosulfate based Rapid Fixer. Inclusion of hardener interferes with chemical diffusion - which is critical to archival fixing and washing. I use only a water rinse post development - no acid stop bath.

IMO, considerable testing (for silver and fixing residues - post fixing and washing) would be required in order to assess the impact of hardening stop bath on the archival characteristics of the processed film.

Photo Engineer · Jan 1, 2006

If you use chrome alum be aware of a few facts.

1. It spoils rather rapidly and loses effectiveness.

2. It requires a rinse after use before you go into the fixer to prevent pH problems (this depends on the type of fix you use)

3. It is often used before development, with a subsequent rinse to remove the chrome alum. In fact, many early processes used a prehardener. One of the most popular used formalin and sodium sulfate at pH 9.

PE

nworth · Jan 1, 2006

Rapid fixer with hardener works fine for almost all purposes. Just make sure you wash your negatives thoroughly. It makes washing a bit more difficult. A half-hour should do, but the Ilford method is probably out (unless you modify it for somewhat longer times and a few more changes of water). Chrome alum is used when processing at high temperatures or when a bit more hardening is desired. A chrome alum stop bath may help prevent swelling and damage in the fixer, expecially in machine processing. The disadvantages are availability plus the things PE cited above. Another possibility is to use SH-1 or SH-5 after fixing and rinsing, followed by another thorough rinse.

Tom Hoskinson · Jan 2, 2006

nworth said:
Rapid fixer with hardener works fine for almost all purposes. Just make sure you wash your negatives thoroughly. It makes washing a bit more difficult. A half-hour should do, but the Ilford method is probably out (unless you modify it for somewhat longer times and a few more changes of water). QUOTE]

That was my point. The byproducts of fixing require diffusion to move them into the wash water and thus remove them from the emulsion - and that means soaking for some time in several changes of water. We know what "some time" is and "how many fill and dump cycles are required" from the experimental data published by Ilford and Kodak for Rapid Fixing with non-hardening Ammonium Thiosulfate Rapid Fixers.

We do not know the "soak time" and number of "fill and dump cycles" required for archival washing after using either a hardening stop bath or a hardening fixer if someone has taken this data, I'd like a copy of it or a reference. We do know that archival processing guidelines explicitly call out the use of non-hardening fixer.

dancqu · Jan 2, 2006

Tom Hoskinson said:
We do know that archival processing guidelines
explicitly call out the use of non-hardening fixer.

Now just who was it that drew that line. I'd like
to have his name. That is a limitation of the techniques
available to those who produce works of interest. The
next "guidelines" may restrict the films we use and
define our range of alternative processes. I think
it an abridgment of the Supreme Court's broad
interpretation of our Freedom of Speech.

Besides, what's the point of outlawing hardener?
As I understand it some films are so hardened
in an incorporated manor that there is no
point to adding more. Dan

avandesande · Jan 2, 2006

I haven't done any testing, but I think that the unique properties of efke (thin film capable of expansion) might have to do with the unhardened emulsion. A pre hardening bath would change the development properties of the film.
I try to handle the film carefully, but if a piece of dust gets on the film before it is dry it is there permanently. I would like to try to mitigate this by hardening in the fix.. I wash film for at least an hour anyway. I am going to switch to distilled water for everything up to the washing step.

Tom Hoskinson · Jan 2, 2006

dancqu said:
Now just who was it that drew that line. I'd like
to have his name. Dan

Dan, There was a recent Apug Post (lasrt 2-3 weeks) that cited a list of "photographic processing criteria" for Archivists. I'll see if I can find it and post the URL and any references.

Seems like it should be possible to do some residual silver level testing post fixing and compare the levels in hardened Efke versus the levels in unhardened Efke.

The second step would check for fixer residue (post washing) in hardened verssus unhardened Efke.

And yes, in the past, I pre-hardened the old style false color 35mm E4 Ektachrome ( I used formaldehyde based hardener etc.)before developing it in the E6 Process.

Gerald Koch · Jan 2, 2006

Chrome alum provides considerably more hardening than common (white) alum. If it is used as a stop bath and followed by a minute or so rinse then any fixing bath can be used, even an alkaline one.

dancqu · Jan 6, 2006

avandesande said:
"... I think that the unique properties of efke ...
might have to do with the unhardened emulsion."

That Efke emulsions are not pre-hardened there is
NO argument.
That all other emulsions are pre-hardened there is
NO argument.

So, use a fix with hardener and join the rest of the pack.
Acid stop and fix.

"I wash film for at least an hour anyway." A BIG waste
of time and water.

"I am going to switch to distilled water for everything up
to the washing step."

And through the first wash especially and all at
room temperature. Dan

Photo Engineer · Jan 6, 2006

I am sure EFKE emulsions are pre-hardened (the term for hardening at the factory is fore-hardened BTW, so I really mean fore-hardended).

If they were not, they would not really survive processing very well. However, the hardening is probably one of the first generation hardeners such as formalin, glyoxal or chrome alum. But then who knows.

Unhardened gelatin melts at 68 deg F or about 20 deg C. If an EFKE emulsion washes off entirely at that temperature then there is no hardener in it.

Pre-hardening refers to the use of a hardener before the developer. It may be followed by a wash or a neutralizer and wash to prevent bad things from happening in the developer.

Any film can be hardened even more than it already is, by use of an appropriate hardener. If interested, I can give details on several methods.

PE
PE

jim appleyard · Jan 6, 2006

You could always try using a pyro dev. I haven't shot any Efke films, but lots of folks say that they tan well. The tanning action of pyrogallol acts as a hardener. In using up the last of my APX 25 in 120 size, I've noticed that the emulsion is easily damaged. I've taken to using PMK for my dev. and the problem has ended. BTW, I was, and still am, extremely careful of handling the film during processing.

removed account4 · Jan 6, 2006

Tom Hoskinson said:
Dan, There was a recent Apug Post (lasrt 2-3 weeks) that cited a list of "photographic processing criteria" for Archivists. I'll see if I can find it and post the URL and any references.

tom,

i think the thread you were referring to was called (there was a url link here which no longer exists).
i posted the guidelines for habs/haer photographic documentations.
in the guidelines they mention that submissions with hardened fixers will not be accepted.

-john

Tom Hoskinson · Jan 7, 2006

Yes, that's it, John. Thanks!

Whiteymorange · Jan 8, 2006

For what it's worth:
After a particularly disquieting discovery that many of the strips of 120 Efke 50 that I had processed were peeling apart - the emulsion lifting from the base, I wrote to J and C about it. John was great about following up on it with the factory. I had used Sprint chemistry with hardener added to the fixer in the suggested amount, the same set-up we have used for years in our school darkroom on Ilford and Kodak films. There were different batches of chemicals mixed and used over the period of a couple of weeks, but the same measurements and the same stock. No other film processed at the same time, using the same chemicals, had any problem at all. I had shot Tmax 100 and HP5 and processed them the same weeks. The factory immediately questioned the use of a hardening fix and, short of telling me that this was the reason that the film had separated, suggested that this was not a good idea - that I had probably "over hardened" the film.

I have not had a repeat of that experience recently (that was two summers ago) and I have processed Efke in 35, 120 and 2.25x3.25 sheets in hardening and non-hardening fixer, but far less of it than I did in those two weeks. I must admit that I'm kinda shy of the stuff these days, though I do love the look and like having the small sheets for my Busch Pressman.

Photo Engineer · Jan 8, 2006

When the emulsion peels from the support, and still retains its integrity, then the problem is a bad subbing layer between the emulsion and the support.

This is called the 'pad' at EK. If it is bad, you get exactly the results you report.

PE

Chrome alum vs hardening fixer?

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