Effect of HIGH dilutions HC-110 Tri-X?

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Hi, I've been using HC-110 dilution 'B' with Tri-X for years. Mostly shooting 6X7. 1-What is the effect of greater dilutions? 2-What difference will you see with intermittant vs. Jobo agitation? I read that Ansel Adams actually developed for 18 minutes with 15 secs agitation every 3-4 minutes or so! (for compensation effect?)

Any input appreciated. I do have a densitomter and run Zone 1 and Zone 8 tests to calibrate film/developer. Thanks, Howard

-- Howard Posner (hposner1@swarthmore.edu), October 16, 2001

Answers

It depends how high a dilution you're talking about, Howard.
If you dilute any developer to the point where the maximum density of the negative is affected, then it automatically becomes a compensating developer. That is to say; the film curve will show a distinct and early 'shoulder', where highlight density flattens off. The mid tones and shadows are relatively unaffected, so it's a useful technique for dealing with long tonal range subjects.
The look of the print is quite distinct from simply pulling a normal development, since the mid-tone separation is maintained and only the highlights are compressed.

Compensating developers are best used with 'stand' or semi-stand agitation, since this enhances the effect, by starving the highlights of fresh developer.
The method that you describe of Ansel Adams' is a good example of semi-stand agitation. Using a Jobo would defeat the object, I expect.
I don't use HC-110, so I can't tell you exactly how far you have to dilute it to turn it into a compensating developer. 'Quite a lot' would be my best guess.

-- Pete Andrews (p.l.andrews@bham.ac.uk), October 17, 2001.


Bruce Barnbaum has a section in his book (The Art of Photography) on highly diluted HC-110, also a two bath HC-110 which includes times,agitation methods, etc.

-- Don Sparks (Harleyman7@aol.com), October 17, 2001.

Ansel Adams in "The Negative" describes the use of HC-110 at 1:120 dilution. The minimal agitation is to enhance the compensating effect in the highlights. You could expect more edge effects and more grain. The text below is copied from one of Richard Knoppow's erudite answers to a similar question in rec.photo.darkroom. I hope that it is in order for it to be pasted here.

"I think the chemical rule of thumb is that time is increased at about the square root of the dilution. e.g. diluting 1:1 should take about 1.4 times as long to reach the same contrast. Some effects of dilution depend on the formulation of the developer. High-sulfite developers may produce slight additional film speed when diluted because of the lowered concentration of Sulfite. They will also be a little grainier. Highly active developers may exhibit just the reverse effects. Many developers will produce increased "edge effects" due to local exhaustion of the developing agents and build up of reaction products at the interfaces of high and low density areas. Again, the lowered sulfite contcenration will tend to cause this since part of the function of the sulfite is to regenerate the reaction procucts. Diluted developers, again because of lower sulfite concentration, will have shorter lifetime than full-strength solutions since the sulfite will be less able to protect the reducing agents from oxidation from dissolved air or air at the surfaces. Edge effects are also partially controlled by the amount of solution which can be held by the gelatin emulsion. Modern films have rather thin emulsion layers so are more likely to show the effects of diluted developer or lack of agitation. A developer like D-76 will have very similar characteristics at 1:1 as it has at full strength but at 1:3 will start exhibiting very strong edge effects with many films. If a developer is diluted enough it may start to run into problems with general exhaustion of the reducing agents. Such a developer may produce very low contrast and low densities even with extended development times. The localized effect of such exhastion will be exagerated "compensation" which is actually sometimes useful." --- Richard Knoppow Los Angeles, Ca. dickburk@ix.netcom.com

-- john stockdale (jo.sto@bigpond.com), October 17, 2001.


I've used HC-110 with Tri-X sheet film at up to 1:30 (from stock not concentrate) such as Adams mentions. You will have to give an extra 1/2 stop of exposure or so or you will end up with pretty thin negatives. As Pete says a Jobo defeats the purpose of using high dilutions for compensating effects. For extreme highlights I think I would rather try a divided developer, I didn't really see any great difference using HC-110 at such a high dilution over a more moderate dilution with shorter developing times, but your results may vary!

-- Andy (akkup@mindspring.com), October 17, 2001.

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