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  1. #1
    Mateo's Avatar
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    dichromate in developer

    Just curious, what is the advantage of using dichromate in potassium oxalate in addition to Na2 in the coating. The Na2 contrast agent seems to take care of all my negatives so I'm wondering why people also use the dichromate. Anybody?

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    Quote Originally Posted by Mateo
    Just curious, what is the advantage of using dichromate in potassium oxalate in addition to Na2 in the coating. The Na2 contrast agent seems to take care of all my negatives so I'm wondering why people also use the dichromate. Anybody?
    I have founnd that I can fine tune the contrast better with the dichromate method. The platinate is such an agressive restrainer that very little goes a long way and sometimes I find it hard to find a small enough dilution to make small changes.
    In my case I only use platinum to preven solarization, so I rarely use platinate as a restrainng agent.

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    Mateo's Avatar
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    Any idea how little Na2 can be used in the sensitizer? I've been able to get away with 1 drop of 2.5% for an 8x10 without fogging and Kevin Sullivan says that he can do pure palladium prints without contrasting agent. I've been considering the dichromate method but having that many bottles of dev seems to be a pita. Is it worth it?

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    Quote Originally Posted by Mateo
    Any idea how little Na2 can be used in the sensitizer? I've been able to get away with 1 drop of 2.5% for an 8x10 without fogging and Kevin Sullivan says that he can do pure palladium prints without contrasting agent. I've been considering the dichromate method but having that many bottles of dev seems to be a pita. Is it worth it?
    I do pure palladium with the dichromate method and it works for me. I guess it is all in how you like to work, it seems to me you are doing fine, why change? If you calibrate everything you will find you only use one or two bottles, and have the rest for emergencies. I typically use my developer #2 and #3. WHich have 2ml dic rhomate/200 ml developer and 3 ml/200 ml. Typically I am working with DRs of 1.4 to 1.6. But I have messed up and done prints with a DR of .6 by using my developer #5 plus 3 drops of chlorate .6%.

    To onaswer your question, to me is worth it, it might not be to you. Your prints are beautiful, if it aint broke, dont fix it.

  5. #5
    Mateo's Avatar
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    I guess I'm just looking to do something that ain't possible. I've got a work print with high values and low values right where they belong but I wish the areas at zone VI were closer to zone V. I was hoping that you guys used the dichromate because it effected contrast in a different way than Na2 so that I could put a subtle kink in the printing curve to make the print look like I want it to. The neg is as good as I'm ever going to make one and the zone VI should print where it does I just think it would look better if I could change it. I guess I'll have to dodge/burn or make a mask. Thanks Jorge.

  6. #6
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    Quote Originally Posted by Mateo
    I guess I'm just looking to do something that ain't possible. I've got a work print with high values and low values right where they belong but I wish the areas at zone VI were closer to zone V. I was hoping that you guys used the dichromate because it effected contrast in a different way than Na2 so that I could put a subtle kink in the printing curve to make the print look like I want it to. The neg is as good as I'm ever going to make one and the zone VI should print where it does I just think it would look better if I could change it. I guess I'll have to dodge/burn or make a mask. Thanks Jorge.
    Mateo:

    i use dichromate in the developer because it will not change the image color of a pure palladium print. I find that on the papers i really like, the Na2 will appreciably cool down the image tone even when used in very small quantities.

    As far as doing what you what with the printing curve, it sounds to me like it may be time for you try gumover platinum. Because the exposure scale of gum is much shorter than palladium, you can do all sorts of tonal curve manipulation by choosing the contrast and exposure of the gum layer. It is a great way to increase the shadow contrast of a print for instance. You just make a platinum prints with weakish low contrast shadow tones, and then put a gum layer on with a short brief exposure. It will pump density in the shadows and leave the highlights alone.

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    In addition to Clay's response, I feel that the dichromate method is superior to other contrast control methods (including NA2) because it enables a more consistant workflow. I can coat up several sheets of paper, and work with subtle changes in contrast at the developer end, not by recoating more paper.

    I often will try the developer mix on either side of the ideal, simply to ensure that the one I have selected is doing what I want in the image. This is more complicated and time consuming if I have to make coating adjustments to obtain the contrast desired.

    I see NA2 as a last-resort contrast agent, not as the primary method for adjusting contrast. Others have switched to it, but I don't see it working as well in my workflow.

    ---Michael

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    I have been using the dichromate in the dev. for most of my printing with using the NA2 very sparingly to just kind of tweak a print once in a while. A mistake I made in the beginning was to mix alit of different cox dev and dichromate combinations and now like Jorge I use mostly #2 and #3 mix. It took me awhile to figure out I could further dilute those bottles like #6 that I didn't use to get a #3 mixture ( I've never been accused of being too bright).
    I like the color of the prints with the dichromate method much better.

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    What about peroxide in the sensitizer? I don't know of any way to adjust middle tones without affecting the other ends of the curve, but I'd love for someone to test all the methods and report back.

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    Quote Originally Posted by cjarvis
    What about peroxide in the sensitizer? I don't know of any way to adjust middle tones without affecting the other ends of the curve, but I'd love for someone to test all the methods and report back.
    A few drops of hydrogen peroxide added to 2ml of sensitizer will get rid of some slight fogging that you may get with pure palladium. The result is similar to what you would get by adding a drop of 2.5% Na2 to the same amount of sensitizer, or adding about 1ml of a 5% potassium dichromate per liter of potassium oxalate developer. However, as far as I know no one has designed a contrast control system based only on hydrogen peroxide.

    On the whole I find both the Na2 method and the dichromate method about equally effective in contrast control. The Na2 method requires fewer solutions and gives good results with low contrast negatives, but gives cooler tones than pure palladium. The dichromate method allows slightly finer contrast adjustments and keeps the warm tones of palladium but gives poor results (grainy prints) with low contrast negatives. Both methods are in my opinion much easier to use than the old A+B method.

    BTW, choice of UV light source may be a way that can be used to change the slope of the curve in the mid tones without changing it in the toe and shoulders. When I compared the curve of a SA light to that of a BL or Nu-Arc metal halide lamp I found that the SA gave a straighter line response with a shorter toe and less shouldering. These results were based on a 1:4 platinum/palladium mix, mixed 1:1 with FO and no further contrast control.

    Sandy

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