Develop to Completion - test dilemma

Michael R 1974 said:

I'm still at a loss with respect to the purpose of this test. What is it supposed to tell you? What is it for?

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Tells you how long you can develop paper for before its gets development fog. But as paper ages then old test is meaningless. If developer strength changes, which it will with usage then test becomes meaningless.

Print to max black time should always happen before paper starts to fog from development so all the dev fog test will do is tell you if your paper has gone off and even that is debatable.

But since ilford recommended print times are upto 5 minutes you would NOT want any development fogging in less time than that.

In my experience, there is usually a reasonably wide range of development times that yield high quality prints. I usually aim at something longer to help minimize variations.

A related idea though is to use Factorial Development to help make results more consistent between sessions, and to adjust for developer exhaustion.

Here is a thread about that: (there was a url link here which no longer exists)

Rudeofus said:

Operating open trays with photochemistry in complete darkness is not something I would recommend to anyone except under the most special circumstances. If safelights are a concern, I'd recommend leaving a test strip out there for 5-10 minutes, then develop&fix. If this test strip turns out noticeably darker than a test strip going directly into developer&fixer, then yes, safelights do need closer attention.

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Rudi,

Using photo chemistry in open trays in total darkness is standard operating procedure for developing sheet film in trays. I do it all the time Doing it once in a while as a safelight check or the like is easy-peasy.

Michael R 1974 said:

... I must admit I don't see any point whatsoever to the test described in the original post, in relation to print quality. It only tests for one specific thing, and there is no defined purpose. The test does not establish "development to completion", nor does it consider tonality at the various development times. ... I'm still at a loss with respect to the purpose of this test. What is it supposed to tell you? What is it for? ...

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Such a test is to determine "how long is too long," i.e., when the paper starts to exhibit fog from the developer. In my experience, this point is fairly long for FB papers; somewhere in the 6-10 minute range. As for "developing to completion," Gerald explains it above admirably. I think of it also as four phases:

1. induction (when the paper sits there and then finally a faint image starts to emerge),
2. contrast building or "reaching final curve shape" (the real developing happens here, and for most papers, the curve shape is reached at the end of this stage and doesn't change after that; max black is attained and the final contrast is established.)
3. A period in which the extended development causes the curve to move to the right on the chart, in essence, the same effect as giving a bit more print exposure. I use this to fine-tune exposure all the time. Fifteen extra seconds of development gives a noticeable difference at development times between two and four minutes. This is helpful when I've already got tricky dodging and burning down and just need a bit more general exposure; instead of exposing more, I'll just develop a bit more. But...
4. After a certain time in the developer, the whites begin to fog. At this point, contrast decreases by being compressed from the fog; highlight separation and max white suffer.

This latter is undesirable and what the OP is testing for. It seems to me, however, that not only would it be different from paper to paper and batch to batch, but would also vary with the age of the paper. It might be a good test to do to check, however, if you are using relatively long development times and suspect fog for a particular paper at that time.

Doc W said:

That raises this question: what is the point of development to completion? I know that I should not leave paper in the developer for too long, so what is too long and how do I determine what is too long?

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Doc, See the last paragraph above. However, mostly what we want to do is avoid underdevelopment. Only when the paper has reached the point where the curve shape has been established and maximum black and contrast are possible is the print really fully developed. The manufacturer gives you this time, however, so just use it if in doubt. Extending development will give an effect just like adding more exposure till the fog point is reached. This seems to be what you're testing for.

Doc W said:

Stop the presses!
Hexavelent, a local Apugger, came by to help and was suspicious of the results so far. He said the test strips looked like they were printing out. He suspected that the fixer was bad - the SECOND batch of fixer - so we put a piece of film in it just to check. Nothing. The film didn't budge. That fixer might as well have been gin (which I surely need about now). ...

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It's always good to do tests with fresh chemistry I'm curious to know what the problem was with your fixer, since you indicate that you mixed a fresh batch of fix for the second round of tests. Any ideas? Stock stored too long?

BTW, your "fog" was just the uncleared emulsion that was slowly turning brown due to exposure to light. Now you know what happens to prints when the fixer is spent

Best,

Doremus

Thanks for all the great replies. I realize that this test would have to be done every time one began a printing session. Fortunately, it really doesn't take long (except when one screws it up, as I have). Combined with factorial development, I assumed that it would give me just a little more control over the print. I am always looking for ways to improve my prints and Rudman's testing recommendations seemed to make sense to me. However, as some of you have suggested, perhaps visual scrutiny while the paper is in the developer, is the superior method.

Doremus: I contacted Ilford with regard to batch numbers and they informed me that my fixer was manufactured in August, 2008! I bought it at Henry's, in Ottawa, Canada, less than a year ago, possibly a little more, but not much more. This explains clearly why Henry's wants to get out of the film photography business. Product is just not moving. Ilford doesn't print expiry dates (unlike Kodak) which is obviously a problem. I may have to switch to a Kodak alternative or perhaps brew my own.

In any case, thanks to all who responded. I have a much better understanding of "development to completion" and I have become a little more attentive to chemistry shelf-life.

PS: Ilford kindly offered to check the batch number on any product so I could return it if it was outdated. Good folks at Ilford.

Which number on the box of paper is the batch number?

Dumb Dave

DAK said:

Which number on the box of paper is the batch number?

Dumb Dave

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There appear to be two numbers. One is preceded by "CAT" and the other is the batch number.

As for the safelight, if it were any darker in that darkroom, I would probably trip and kill myself.

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If you have followed the previous advice for testing your safelights and have found that your safelights are not safe for the period of time that you need from exposing the print, burning and development, there is another couple of simple solutions that you can use. These are some of the things I have employed with some students I have had who have poor visibility is dim light (by no means all of whom are more senior in years I may add).

Firstly, what colour are the walls in your darkroom? - other than close to the enlarger your walls should be a light colour so that they reflect the light from the safelight better. My own darkroom has slightly off-white walls simply because when I took over the darkroom the walls were a dark nicotine colour and painting them with white paint left me with an off-white colour.

Secondly, there is a very simple way to reduce the time that your paper is exposed to the safelights. Simply buy a water resistant piece of opaque material (in the UK this is commonly known as plastic card or Kunststoffplatte or Kunststoff für modellbau / Modellbauwerkstoffen in Germany) that is a couple of centimetres larger than your tray to use as a ‘lid’ for the tray. Place the paper in the developer, make sure it is fully submerged and then put the lid on and develop for your usual developing time thereby reducing the paper’s exposure to the safelight and allowing you to work in a brighter darkroom - By the way, I first employed this method back in the day so that I could work with black trays and a black lid so that I could process Cibachromes in safelight conditions and it worked just great.

Tells you how long you can develop paper for before its gets development fog.

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My usual processing time for FB paper with Dokumol at 1 + 6 is 3 minutes which produces no chemical fog. I have tested this combination up to 8 minutes and there has been no chemical fog and I have never personally observed chemical fogging.

What I have seen with many students is fog resulting from:

• Safelights that are the wrong colour / too old / too bright or too near to the enlarger and/or developer (the solution being to correctly test safelights, reposition them or, if it is then too dark for the darkroom worker employing the ‘lid method’).
• Fog resulting from older paper - usually resulting from buying older paper to save money or long gaps between printing sessions (the solution being to add a 1% solution of Benzotriazole in stages of 15 ml per litre to the developer until the fogging is no longer apparent).

Bests,

David.
www.dsallen.de

David, thanks for the detailed response. I don't think that the issue is the safelight, but just for the record, I use two safelights from B&H that I bought ages ago. I think they are pretty generic and probably produced under a variety of names (mine are labelled "Coastar"). They have a grey metallic finish and look to be OC plastic. Like this. One safe light is positioned about 5 ft (1.5 m) from the enlarger easel. This safelight is also about 15 ft (4.6 m) from the developer tray. The other safelight is above the developer tray (about 3 ft/0.9 m)) and pointed slightly so it is not shining directly at the developer. The walls of the darkroom are matte white, except behind the enlargers where the wall is matte black.

I did a safe light test as follows: I put a test strip half under a piece of opaque plastic. On the other side, I put coins in a row, at 30 second intervals, for 5 minutes. I developed in Dektol (either 1:2 or 1:3 - I can't remember now) and developed the strip. It was completely blank. What safe light tests do you suggest? As I said, I think the safe lights are ok with regard to their proximity to the enlarger, and I think the "coin test" shows that, but now I am wondering about the distance from the developer tray.

The Kodak safelight test is very thorough: http://wwwca.kodak.com/global/en/consumer/products/techInfo/k4/k4TestSafelite.shtml

The important thing about this test (and other good tests) is that it tests on paper that has already received sufficient exposure to be above the "threshold" for minimal exposure.

The Kodak safelight test is very thorough: http://wwwca.kodak.com/global/en/con...Safelite.shtml

The important thing about this test (and other good tests) is that it tests on paper that has already received sufficient exposure to be above the "threshold" for minimal exposure.

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+1

I don't have a reflection densitometer. Is there any alternative?

Doc W said:

I don't have a reflection densitometer. Is there any alternative?

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You don't need one for the safelight test. The light gray background tone you see in the linked Kodak article will work quite well, even when you just approximate it by eye.