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  1. #11

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    Quote Originally Posted by jdef
    Ryuji, that might be true. Have you tested this, or are you relying on theory?
    Figuring out the balance in the formulation is going to be a pain as I pointed out in a previous thread.

    It kind of reminds me of when VW made a dual-engined Scirocco Pro-Rally car. It was a really interesting approach to getting over 400 hp into the VW with a little weight penalty, but since there was no connection between the front and rear wheels, it was really easy to spin the car out if the driver let off the throttle too quick at high speeds on loose surfaces. Like when you are racing up Pikes Peak - a place where you do not want to spin out...

    I suppose nowadays with computer-run traction control this approach would work better. So I guess you just need a way to get computer-run development control in your 3 developing agent developer to maximize and controll the output of the 3 developing agents and any superadditivity they create.

  2. #12
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    Quote Originally Posted by Ryuji
    There is no advantage in using two bath print developer. There is probably bigger disadvantages in doing so.
    You may well be right about the hydroquinone being unnecessary in a PC developer, but I couldn't disagree more with your take on divided developer. Although I would tend to agree with you with regard to film development, for paper, it's a very different story. Here are some of the advantages that have kept me faithful to divided paper developers for more than 25 years. (I'm talking about a developer where all the reducing agents are in Bath A and the alkaline is in Bath B. No rinse between the two.

    1. Within all but extreme limits, one can ignore time and temperature variables. Any temperature will do. Not only will ambient room temperature work just fine, so will ambient water temperature, even if that is fairly significantly (10-15 degrees F.) different from room temp.

    2. Near perfect repeatability when making multiple prints from the same negative, assuming same exposure controls under the enlarger. Since all that happens in Bath A is that the latent image soaks up the volume of developing agents that it needs, and in Bath B develops to exhaustion (but no further!), repeatability is ensured. Bath A doesn't become exhausted--just used up volumetrically. As Bath B becomes exhausted, it may take longer (more than a minute) to develop the print fully and/or the blacks may become weak. When that happens (after about 40 8X10's), I just dump it and mix some more. Since it's only Washing Soda (carbonate) and water, it's mere pennies.

    3. Excellent contrast control. Since I now use only multicontrast paper, this is not as much an advantage as it is with graded papers. When I used graded papers exclusively, I used to have two Bath A's-- one a straight metol/sulfite formula similar to Selectol Soft and one more like Dektol with metol/sulfite/HQ. Depending on what I was looking for in the final print, a #2 paper run through the soft Bath A would give me a #1 1/2 grade. A number # paper run through the harder Bath A would give me a #2 1/2 grade. In other words, I had half-grade controls.

    4. When I was doing a lot of Cibachromes/Ilfochromes, I used my own divided homebrew instead of Ilford's to control the high contrast inherent in the process. It also effectively eliminated the need for temperature controls, since it's only the developer that had needed to be controlled anyway. Didn't matter a hoot with the bleach and fix-- just took longer or shorter depending on the ambient temp. Dividing the developer was a much easier solution to high Ilfochrome contrast than making masks.

    5. It's dirt cheap. Since Bath A will easily keep for 6-8 months before becoming oxidized, and Bath B costs mere pennies per batch, I don't spend a lot of money on chemistry.

    6. Since one cannot alter the print in the developer stage by either over or under-developing, it tends to make one a better printer at the exposure end of things. What manipulation you do has to be done under the enlarger. Since I also use split filter printing (1 exposure each at full magenta and full cyan), that combined with divided development gives me a lot fewer headaches in the darkroom.

    So perhaps none of these advantages look particularly compelling to you, but to me, they are.

    Larry

  3. #13

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    Quote Originally Posted by jdef
    Allow me to clarify. I am not arguing that the hydroquinone is necessary or beneficial, because I don't know. I do know that the developer I noted above works very well, and lasts for a long time. Given my recent experiments with the MC 2-bath developer, I'm inclined to believe you're all right about the Q, except perhaps where the keeping properties are concerned. Maybe it would be more beneficial to leave out the ascorbic acid?

    Jay
    You should prepare otherwise identical solutions, one containing hq and the other none, with pH adjusted to same value, and store them at identical aerobic condition for some time, and take samples from time to time to assay them for pH, reduction potential, photographic performance, etc. If you see the efficacy of hq as a way to improve the solution shelf life, you'll realize other methods such as ones I've been using to be superior.

    Larry, I don't have time to respond to your opinion, but the exhaustion effect (seasoning and oxidation) of paper developer is quite different from film developers, and there is little benefit in doing two bath as you described. Replenishment is a better way. Modern printing paper emulsions are designed for rapid one bath development when highest Dmax is desired. Indeed, the density of blacks above a certain point is not a function of amount of developed silver per unit area, but instead in the way the grain was developed (the amount of silver per unit area gets saturated before the density does). Slower development, such as given by two bath technique, will soften the shoulder and shadow contrast will be insufficient to match with most negative films.

    (by the way, the same mechanism applies to the negative development. shoulder shape can be modified somewhat by adjusting relevant parameters)

  4. #14

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    Continuation. Most modern paper emulsions are chlorobromide emulsion. These emulsions have much less seasoning effect compared to camera negative emulsions. So, there is little or no need to bleed the developer bath when replenishing, unless there is a need to discard the solution to keep the constant total volume. Print developers are very suitable for replenished use, both in b&w and color, and the running cost is very low this way. I keep my print developer (an updated version of DS-14) in slot processor for 6+ months with replenishment, and the developer maintains good performance for this period of time. I also tray process prints larger than 20x24 inches, but DS-14 can be kept in an open tray for a very long session of 24 hours (with breaks, of course) with no detectable change when properly replenished. In many automatic processing machines, developer baths are replenished by tablets so that there is no need to remove solution to adjust the volume any more.

    There seems few developer/replenisher systems for b&w print development, but if you do it, the cost can be made VERY low (and help minimize chemical wastes), even if you start over every few printing sessions.

  5. #15
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    Quote Originally Posted by Maine-iac

    1. Within all but extreme limits, one can ignore time and temperature variables. Any temperature will do. Not only will ambient room temperature work just fine, so will ambient water temperature, even if that is fairly significantly (10-15 degrees F.) different from room temp.

    Diffusion varies with temperature and therefore would have a large impact on the rate of imbibition and loss of solution A when transferred to solution B. This would be especially true in Cibachrome where the material is a multilayer with severe diffusion constraints.

    As far as being applicable to papers, I tend to agree with all of the comments here that this methodology is not optimal for papers but may have some merit with some films.

    It should be noted that the modern papers in question are very high chloride and some are chloroiodide or chlorobromoiodide. With high chloride, has it struck anyone that bromide alone (as found in Dektol) is not the restrainer of choice in print developers compounded for these papers?

    As papers evolve, the developers and restrainers should probably have evolved to match the paper halides. This has taken place in color paper R&D but not in B&W paper R&D. It is interesting to note that using a paper developer with a rebalanced restrainer content has given me up to a stop or more in speed and interesting results in curve shape and image tone.

    I'm not saying it is a necessary thing to do, but it certainly is interesting to me.

    PE

  6. #16
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    Jay, it depends on the paper. Use chloride in a Dektol scratch mix for example, instead of bromide if your paper is a high or pure chloride. You would have to adjust concentration and do a series rather than just a 1:1 molar or weight replacement. I've used from 0.1 - 1 g/l in the working solution and gotten different results from different papers. A bromide / chloride mixture might be warranted as well. I did that once but the results were inconclusive, so I may have used the wrong level or ratio, I just made a wild stab.

    Basically, I find that the papers seem to benefit to some degree from using a customized developer just as a film does. Of course there is no image structure to worry about, mainly curve shape in the mid scale and toe and shoulder.

    And, regarding some comments above. Regardless of how much silver you coat or develop, a paper is physically limited to a maximum achievable density. This is generally between 1.8 and 2.4 depending on the type of paper surface, and the effect is caused by multiple internal reflections attenuating the light you shine on the print.

    So generally, dmax does not enter into this discussion, only the curve from dmin to the start of rollover at dmax.

    PE

  7. #17
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    Quote Originally Posted by Ryuji
    the exhaustion effect (seasoning and oxidation) of paper developer is quite different from film developers, and there is little benefit in doing two bath as you described. Replenishment is a better way. Modern printing paper emulsions are designed for rapid one bath development when highest Dmax is desired. Indeed, the density of blacks above a certain point is not a function of amount of developed silver per unit area, but instead in the way the grain was developed (the amount of silver per unit area gets saturated before the density does). Slower development, such as given by two bath technique, will soften the shoulder and shadow contrast will be insufficient to match with most negative films.

    (by the way, the same mechanism applies to the negative development. shoulder shape can be modified somewhat by adjusting relevant parameters)
    Ryuji,

    I don't know what you mean when you speak of modern paper emulsioins being designed for one-bath developers and the D-Max being better in a one-bath developer than a two-bath.

    That's simply not my experience though I freely admit that I do not have the theoretical knowledge of chemistry that you do. I suspect that most, if not all papers, going back many years were originally designed for one-bath developers. This doesn't mean that divided development is without advantages. As for the D-Max, though I don't read my prints with a densitometer, I cannot tell any visual difference in the blacks in prints made with one-bath developer and the blacks in prints made with a divided developer. Both look visually to be equal in depth and density. If I didn't get rich deep blacks, I wouldn't use the divided formula.

    My point was not to say that prints made with divided developer are necessarily better than those made with a one-bath. I do think the two-bath process as I've outlined it does offer easier contrast control, better repeatability from print to print (of the same negative), and is more convenient in eliminating the need for temperature controls.

    A print in a one-bath developer will continue to develop as long as it's left in that bath. The contrast will continue to increase, the shadows will become darker and darker. In a two-bath, that can't happen, since the activator (carbonate) in bath B can only activate the amount of developing agent soaked up in bath A, and then everything stops. Even if you go away and leave the print in bath B, it will still look the same an hour later.

    I am going to experiment a bit to see what advantages divided development for film might offer. Jay's comments intrigue me (thanks, Jay!). Since I shoot both medium and large format, I wonder if different formulas for Bath A might be able to tame or increase contrast to approximate an N+ or N- development that normally is done by increasing or decreasing time. Also, for roll film, whether a role shot in high-contrast lighting might benefit from the natural compensating effect of divided development. I started this thread to report that my usual one-bath, one-shot film developer (4ml 1% phenidone, 4g Vitamin C (ascorbic acid, not ascorbate), and 5 g metaborate) didn't work as a divided developer. I got blank film, even with 3 minutes in each bath. So obviously I need to either come up with a different formula or difference concentrations of my existing formula. That's where I'd appreciate any help to give me a leg up as a starting point.

    Larry

  8. #18
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    Diffusion varies with temperature and therefore would have a large impact on the rate of imbibition and loss of solution A when transferred to solution B. This would be especially true in Cibachrome where the material is a multilayer with severe diffusion constraints.
    You're correct, of course that diffusion varies with temperature. If I developed my Cibachromes, for example, at 50F, it might take longer than 20 seconds or so for the emulsion (in its various layers) to absorb the developing agents than it would if I were running the process at 70F or 90F. Same with Bath B.

    But, with the divided formula I used, I quickly discovered through trial and error, that the time didn't vary that much, and in fact, it didn't matter how long I left the print in either bath, so long as I left it in long enough for full absorption to take place. In one of my darkrooms, ambient cold water temperature was about 60 and room temp about 65. In the winter, I'd have to run a heater to get it up to 65-67, and keeping the temperature of the chemistry at somewhere close to Ilford's recommendations was a real pain.

    That's what motivated my experiments with a divided homebrew. I was helped by an article in an old Photo Technique on this process, and worked from that as a starting point.

    What I found was, regardless of how cold my darkroom was, and it never got colder than 55, I never had to leave my print in Bath A for more than a minute nor in Bath B for more than 1 1/2 for full development to take place. When I got into warmer darkrooms later on, with a "normal" room temperature of around 70-75, it only took about 30-45 seconds in each bath for full development. And the contrast control was well worth the effort.

    Same for the bleach. Colder temps equaled longer time for full bleaching, but since bleaching can be done in room light, it's quite easy to see when it's done.

    Larry

  9. #19
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    Larry, for the most part modern B&W papers have incorporated developing agents in them. If you use a 2 bath developer, the developing agent washes out in the first bath and therefore imparts a change to the characteristic curve that might be unanticipated.

    To test if your paper has incorporated developer, take some 1% NaOH (sodium hydroxide) solution, and put a drop on a piece of the fogged paper in question. It will turn either black or grey denoting a high or moderate level of developing agent. Of the half dozen or so papers I have, about 1/2 are with developing agents and 1/2 are without. For example, Kodak Polycontrast IV turns black, and Ilford MGIV turns grey.

    BTW, this will also affect the keeping characteristics of the papers concerned. Even refrigeration or freezing might not delay oxidation of these incorporated developers. Only time will tell, as this is rather new to some paper types, and is moot with Kodak B&W papers.

    PE

  10. #20
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    for the most part modern B&W papers have incorporated developing agents in them.
    PE,

    Is this true of the fiber-based papers as well? I know this is true of many of the RC papers, but since I never (or rarely) use them, I haven't concerned myself with it. I use Agfa Multi-contrast FB, Ilford Warmtone FB, and sometimes Forte or Bergger FB. I have never heard that those papers incorporated developer.

    But I'll run the test you suggest.

    Larry

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