Question on Ilford's Wash procedure

[JHannon]

Interesting article
http://www.geocities.com/researchtriangle/thinktank/5693/ilfwash2.pdf

Hans

Thanks for that link Hans. Earlier in the thread Lee posted a version of this same article written in 1998. This is a newer version (2006). Looks like it has some more information on papers too.

This thread has been very informative and I appreciate everyone's help.

 

[Roger Hicks]

Dear John,

Bet you wish you hadn't asked, now...

Cheers,

R.

 

[Ryuji]

Interesting article
http://www.geocities.com/researchtriangle/thinktank/5693/ilfwash2.pdf

There are two major points I like to add to this report. Using demineralized water for washing is not recommended. The author probably used it for conductivimetry in his laboratory, and that's fine, but tap water is generally much more effective washing water than distilled, demineralized or deionized water.

The author mentioned 1.5 microgram per square centimeter as the archival standard. This is not true for 35mm and 120 size films using cellulose triacetate base. 5 micrograms per square centimeter (50mg/sq. m.) is the highest life expectancy rating applicable to this type of film base in current ISO standard. Removing thiosulfate any further has no significant change in the life expectancy of the image.

Therefore, if one follows Suessbrich's procedure with usual tap water, the resulting films will far exceed the current ISO archival standard with considerable safety margin. (Indeed, as I have repeated here, my independent tests show that Ilford method with Boston's tap water washes fixer out of the film to below 1 microgram/square centimeter with a considerable safety margin. This is a level of residual thiosulfate far below the ISO standard for LE100.

On side issues, I alredy described permanganate test is unreliable and should not be used. There are lists of residual thiosulfate tests on my website. Any one of them should be good for this purpose.

The author assumes any rapid fixer should wash out the same from the emulsion. This is not true. Alkaline nonhardening rapid fixer is fastest to wash out of emulsion.

 

[Ryuji]

That's not what I meant. Of course, agitation helps diffusion, because the greater the concentration differential the faster the diffusion, and optimum agitation ensures the highest differential possible until equilibrium is reached. After that, only an exchange with fresh water will do. But I was looking for something else. Absorption?

Absorption is irrelevant here. One factor why washing of thiosulfate is slow has to do with adsorption of thiosulfate on silver grains, gelatin, alum hardeners, and in the case of fiber paper, sizing material and cellulose fibers. Desorption is a different process from diffusion and it has different dependency on temperature (different activation energy).

However, desorption process is not important in washing recent film stocks fixed in non-exhausted fixer (silver level below 5-8g/L) since the residual thiosulfate level will go below the archival standard by just taking diffusion into account. This is not true of fiber paper stock.

 

[Ryuji]

Some find it quicker and easier to wash with running water because they can do something else while the film is washing. If I lived somewhere that there is never a shortage of water I might do the same.

If you want to have a couple of minutes to do something else, do the Ilford process for the first 5 and 10 inversions. If you used initial rinse and vigorous agitation, the residual thiosulfate level is already very low at this point. Instead of the last step of 20 inversions, fill with fresh water, and leave it for a few minutes (or longer). Feel free to boil water and make a cup of tea. By the time you come back the film is ready to dry. This saves a lot of water with little extra work.

 

[david b]

wow...what a thread.

 

[Roger Hicks]

Dear Ryuji,

Makes sense. As it is, I don't find the 20 inversions horribly time-consuming or tiring. I was just trying to think of a situation where I MIGHT use a continuous wash -- if I lived in the Pyrenees with endless spring water, for example.

Thanks,

Cheers,

Roger

 

[RalphLambrecht]

Adsorption. That's the one.

So talking about paper now, how does diffusion and desorption influence the wash? I assume diffusion comes first, but then 'total' desorption has to take place before a final diffusion can do the rest, or do we depend on wash-aid to take care of desorption. This is not clear to me.

 

[Ryuji]

Adsorption. That's the one.

So talking about paper now, how does diffusion and desorption influence the wash? I assume diffusion comes first, but then 'total' desorption has to take place before a final diffusion can do the rest, or do we depend on wash-aid to take care of desorption. This is not clear to me.

That's been discussed several times on APUG and it's also described elsewhere, including my web site. Why don't you search and read first to avoid vast duplication of the matter?

 

[RalphLambrecht]

That's not very helpful, and this message is vast duplication in itself, since you made this suggestion countless times, here and in other forums. You've also gotten the same answer countless times.

Subjects will come up, over and over again. Why?

Everything has been discussed several times elsewhere and can be found in endless searches, resulting in not quite what one was looking for.

...and

It is OK! By all means, search the records, but don't let anyone stop you from asking questions. Don't fear to ask questions that might have been asked before, just because someone might try to patronize you with:

'Why don't you search and read first?'

Unbelievable.

 

[Ryuji]

That's not very helpful, [...]

I know, but I still suggest that you search first and come back if there's any specific question. That question came up so many times and, besides someone often come up with bizarre theory or implausible mechanisms, the conclusion is always the same, and it hasn't changed for decades. I have no fun repeating it. And I'm not hired to do public lecture on APUG or anything. It's taking my time. My Wiki has the answer to your question and more info. It gets several thousand hits each week and there is no reason to expect difficulty in searching there.

 

[RalphLambrecht]

I wish Richard Knoppow would be on APUG.

 

[Kirk Keyes]

I've done the methylene blue test on microfilms and it's not really a hard test. Not as easy as a single solution spot test, but not difficult by chemistry lab levels.

It does require a spectrophotometer and some chemicals that the typical darkroom does not have, like sodium borohydride, and either CD-3 or 4 (I can't remember at this point).

I've got instructions on how to do this type of test (i.e. not the ANSI or ISO standard, but a company SOP) if anyone is interested.

 

[RalphLambrecht]

Kirk

I'm very interested.

 

[Kirk Keyes]

Ralph - I'll look for for it in the next few days. If you don't hear from me send me an email.

Kirk

 

[Bruce Watson]

Using demineralized water for washing is not recommended. The author probably used it for conductivimetry in his laboratory, and that's fine, but tap water is generally much more effective washing water than distilled, demineralized or deionized water.

I'll bite. Why is that?

 

[Kirk Keyes]

I wish Richard Knoppow would be on APUG.

Yeah - what's up with that. Does he use a text only browser like Lynx? (I'm guessing it would make a site like this a pain to read. I haven't actually tried...)

You're a pure-silver guy, Ralph, perhaps you could invite him over...

 

[Ryuji]

I'll bite. Why is that?

Because tap water contains a small amount o f carbonic acid and bicarbonate, which act as a very mild (but effective) washing aid. If you use sulfite washing aid, the difference is relatively unimportant. Or you can add some bicarbonate to deionized water for washing purpose.

Levenson did this type of research pretty thoroughly at Kodak Harrow lab in 50s or maybe 60s.

 

[Ryuji]

I've done the methylene blue test on microfilms and it's not really a hard test. Not as easy as a single solution spot test, but not difficult by chemistry lab levels.

Agreed.

I've got instructions on how to do this type of test (i.e. not the ANSI or ISO standard, but a company SOP) if anyone is interested.

For the original report and background info, read Warburton and Przybylowicz's paper from 60s, whose reference info can be found on my website. For procedure, Kodak Publication H24 Module 3 contains a concise summary.

 

[Kirk Keyes]

Ryuji - can you find a working link on Kodak's web site for the reference you give? Module 3 seems dead from what I can see. http://www.kodak.com/US/en/motion/support/processing/h24.shtml

 

[Ryuji]

Ryuji - can you find a working link on Kodak's web site for the reference you give? Module 3 seems dead from what I can see. http://www.kodak.com/US/en/motion/support/processing/h24.shtml

I have a link to their PDF file (methylene blue test section only) from my wiki page "residual thiosulfate tests" just stick this in the search, and click on the section on methylene blue test.

Addendum:
Kodak Publication H24 Module 3 is actually a 300+ page document, covering analytical protocols used for processes ECN-2, ECP-2, VNF-1, RVNP, b&w and all film and paper processes. The methylene blue test section is found in the last section of this document.

 

[Bruce Watson]

Because tap water contains a small amount o f carbonic acid and bicarbonate, which act as a very mild (but effective) washing aid.

But if the mechanism is actually diffusion, this shouldn't matter. I don't see how this would cause diffusion to work any better or faster. One would think (and I'm certainly not a chemist, so this one might think this wrongly) that deionized water would make the diffusion process as fast as it's going to get.

 

[Ryuji]

But if the mechanism is actually diffusion, this shouldn't matter. I don't see how this would cause diffusion to work any better or faster. One would think (and I'm certainly not a chemist, so this one might think this wrongly) that deionized water would make the diffusion process as fast as it's going to get.

Again, diffusion is only one part of washing, and it is not even rate-limiting stage. The rate limiting stage is desorption, especially if deionized or distilled water is used.

 

[RalphLambrecht]

In other words, make sure desorptions is not rate-limiting in order for diffusion to work as well as it can?

 

[Kirk Keyes]

I have a link to their PDF file (methylene blue test section only) from my wiki page "residual thiosulfate tests" just stick this in the search, and click on the section on methylene blue test.

Hey - you just added that... didn't you? I looked on your page yesterday and I could sear that it wasn't there then...