Dmax measurements of several papers.

Discussion in 'B&W: Film, Paper, Chemistry' started by Donald Miller, Jan 28, 2006.

  1. Donald Miller

    Donald Miller Member

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    I have measured dmax on several papers that I have used frequently. For those who are unfamiliar dmax is the reflective density measurement of the deepest black that a paper will achieve. Higher numbers indicate a deeper black.

    Oriental VCFB 2.14

    Oriental (Grade 2) 2.10

    Azo (Grade 2 and 3) 2.07 and 2.09

    Kentmere Fineprint VC 1.97

    J and C Polywarmtone Classic VC 2.04

    All of these are excellent papers. Today was my first experience with the Kentmere paper. It appears to have a more abrupt toe as it separates high values very nicely.
     
  2. George Papantoniou

    George Papantoniou Member

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    I guess that J&C polywarmtone is made by Forte, huh ? I cannot find the J&C products here, but Forte is easier to lay my hands on...
     
  3. JHannon

    JHannon Member

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    Good stuff Donald. Would the dmax change very much when toning in selenium?
     
  4. Donald Miller

    Donald Miller Member

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    John,

    All measurements were made on the basis of selenium toned tests. All papers were developed in the same developer. This makes this a valid apples to apples comparison.
     
  5. mikepry

    mikepry Subscriber

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    Don,
    Can we safely apply the moniker "Azo Schmazo" then?
     
  6. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    What was the developer, out of curiosity?
     
  7. Donald Miller

    Donald Miller Member

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    The developer in this case was Zone VI diluted 1-3. I used it since I had fresh stock already prepared.
     
  8. Donald Miller

    Donald Miller Member

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    I am not saying anything other then that these are the dmax that my tests indicated.
     
  9. Photo Engineer

    Photo Engineer Subscriber

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    The Dmax of reflection print materials is limited to about 2.2 due to the laws of physics. There are work arounds available to manufacturers that allow higher values to be achieved by putting certain addenda in the topcoat.

    The more matte the surface, in general, the lower the dmax.

    In general, the dmax and the amount of silver developed or coated have little relationship. It is the form of the silver metal that is important to image tone and density.

    PE
     
  10. Alex Hawley

    Alex Hawley Member

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    Great stuff Don and thanks. Thanks to PE too for the additional explanation.

    Since I have never done any densitomer testing, I have two questions:

    (1) what does the numerical spread in the values mean? Is it a large difference between papers or a small difference. Just at face value, it looks like a very small difference.

    (2) Are the differences between the papers detectable to the eye? Understand this is more subjective, but can the differences really be seen and how apparent are they?

    I just recently ran a comparison between Kentmere Bromide (grades 2 and 3) and Azo. No densitomer tests, but to my eyeball, the richness and depth of the deep blacks were indistinguishable.
     
  11. Donald Miller

    Donald Miller Member

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    Alex,

    In many cases, the visual differences are very slight. In fact one would need to have the samples immediately adjacent and even then they may not be apparent as your experience indicates.
     
  12. Alex Hawley

    Alex Hawley Member

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    Thanks Don. To me, your testing shows that the dmax capability of these well-respected papers is nearly the same. In the practical sense, they are the same. There is also a good range of emulsion types here, different manufacturers, plus graded and variable contrast. Kind of debunks those "my paper's black is better than your paper's black" arguments that spring up from time to time.
     
  13. mikepry

    mikepry Subscriber

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    Now Don, you're starting to sound like a politician!
     
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  15. MurrayMinchin

    MurrayMinchin Membership Council Council

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    It's not the depth of the black that matters, but the relationship of print values adjacent to each other.

    Short sermon eh? :wink:

    Murray
     
  16. Photo Engineer

    Photo Engineer Subscriber

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    I have seen spreads like this in the same paper with different levels of gloss due to different polish on the ferrotyping plate. I have seen the same coating with different dmax based on the overcoat and I have also seen dmax vary if you make a print, dry it, measure it, rewet, redry, remeasure and etc. I've seen dmax drop with this procedure from the same sheet of paper. I've also seen it go up with this rewet, redry procedure. It depends on the paper hardness and swell, I'm told.

    Here is another test. Make 2 identical prints and place one on top of the other offset left, then repeat offset right and evaluate the dmax and dmin visually, then flip papers and put the bottom on top with the former top paper on the bottom. Do the offset evaluation of dmax and dmin. You will often get a big surprise from the subjective evaluation of how two otherwise identical prints differ just by position (top / bottom and left / right).

    This latter effect is due to left and right eye differences and the fact that the paper on the bottom has no additional white backing and therefore 'looks' different to the observer.

    These differences can be virtually eliminated by using a MacBeth viewing cabinet with standard light source, and measurments can be done with a spot photometer at about 3 ft distance.

    PE
     
  17. Kirk Keyes

    Kirk Keyes Member

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    On a test of Ilford MG IV FB Glossy (air dried) paper last year, I found the Dmax went from a Visual density of 2.05 untoned to 2.20 with Kodak Rapid Selenium Toner 1:15 in about 4 minutes. Additional time up to 20 minutes added no extra density.

    The color balance went from untoned R=2.04/G=2.15/B=2.08 to R=2.21/G=2.28/B=2.20. Note the difference B to G is about 0.08 in each, while the difference from R to G went from 0.11 in the untoned print to only 0.07 in the toned one. This made the print appear a little less green, and made the print appear more neutral.

    Kirk - www.keyesphoto.com
     
  18. James Bleifus

    James Bleifus Member

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    Wow, Oriental grade 2 has deeper blacks than Azo grade 3. Thanks for the info Donald.

    Cheers, James
     
  19. Kirk Keyes

    Kirk Keyes Member

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    Yeah - deeper by 1/30th of a stop...
     
  20. jp80874

    jp80874 Subscriber

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  21. JBrunner

    JBrunner Moderator Staff Member Moderator

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    It is my understanding that it is the entire curve of AZO from shoulder to toe that gives it its look, and that amidol is an important part of reaching that curve.
     
  22. Alex Hawley

    Alex Hawley Member

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    John,
    I used both Agfa Neutol WA and Don Miller's PPPD with 15 grams of catechtol, no pyrogallol. The description for PPPD is here: http://www.apug.org/forums/showthread.php?t=6952
     
  23. Donald Miller

    Donald Miller Member

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  24. Claire Senft

    Claire Senft Member

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    What dilution and what time and temp were used on the toning ? Were each of the papers tested for the time that delivered the maximum dmax for that particular paper?
     
  25. Mark Layne

    Mark Layne Member

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    Somehow I can always pick my Azo prints out of the pack. Hard to quantify it but its something to do with the way the midtones jump out at you.
    Mark
     
  26. Rlibersky

    Rlibersky Member

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    I though Dmax had to do with only blacks. This doesn't tell us anything about how the final print looks, other then the depth of these blacks. So to try and compare the LOOK of a paper by this measurement is not useful. There are goods reason to know the Dmax, just not comparing the final print.