Platinum Dmax

Discussion in 'Alternative Processes' started by Ian Leake, Jul 12, 2010.

  1. Ian Leake

    Ian Leake Subscriber

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    One for the Pt/Pd obsessives...

    What's the highest Dmax you can consistently achieve with your platinum/palladium prints?

    I can get to about 1.39 with a 2:1 mix of Pt and Pd, and I think I can probably squeeze out a few more ounces of black now that I've built a new printing rig. (Paper white for my paper is about 0.12 if that's relevant.)

    That's a pretty convincing black, but I suspect blacker blacks are possible.

    What's your blackest Pt/Pd black?
     
  2. clay

    clay Subscriber

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    I have a print with a 1.8 dmax that is pure palladium on waxed vellum.
     
  3. Loris Medici

    Loris Medici Member

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    Clay, that means the unwaxed print had a dmax around log 1.5 - 1.6 right? (I think closer to the latter...???) I was using hydrocote polyshield satin few years ago and it was giving me an extra log 0.2 - 0.3...

    Regards,
    Loris.
     
  4. clay

    clay Subscriber

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    Yep, probably about 1.5 without the wax. Best Dmax in my experience is on smooth paper, with generous coating or double coating and printed in nice humid conditions of around 50%.(which we have no shortage of in Houston in the summer)
     
  5. Photo Engineer

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    I cannot speak for Pt/Pd specifically but due to the limitations of paper prints and internal reflections, most all glossy paper prints are limited to a maximum density of 2.2 or less. Matte is lower, about 1.9 or less.

    PE
     
  6. Loris Medici

    Loris Medici Member

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    PE, to my knowing, matte alt. process prints won't give something above log 1.6. (Without any surface treatment, that is...) Perhaps your figure is for matte s/g paper? Plus, I've seen inkjet prints on special glossy papers with log 2.4 density!?

    Regards,
    Loris.
     
  7. Ian Leake

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    Interesting comments about the difference between matte and glossy surfaces. I was vaguely aware of this but hadn't realised that it also applied to platinum (although with hindsight it's obvious!). I work with very matte paper - and it's rough too. This gives a beautiful and rich appearance, but clearly reduces the potential Dmax.
     
  8. Photo Engineer

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    Loris;

    The Dmax varies with normal coated materials based on the presence of an overcoat and how absorbent the fibers of the paper are. It also depends on the presence or absence of some sort of subbing such as baryta.

    So, the figures I gave were ballpark and maximum for hand or machine coated materials. My own coatings, without overcoats and on Strathmore Smooth only achieve about 1.9.

    I have seen reflection prints with a Dmax of 3.0, but this was when tricks were played with overcoats and internal "reflecting" materials such as silicon "chips". This is somewhat the case with digital papers which if you notice, appear to be much more transparent when held up to the light than photographic papers due to some of those "tricks".

    PE
     
  9. Loris Medici

    Loris Medici Member

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    Dear PE,

    Thanks for the clarification. But then, your coatings are s/g emulsion right? These would naturally exceed alt process prints - done on plain paper - in terms of dmax... In case of s/g emulsion (or albumen) the image isn't "in" the paper, it sits "on" the paper inside a binder. Therefore, figures for s/g emulsion aren't comparable for pt/pd and such. I'm not sure if could get log 1.9 on plain paper (suitable for iron processes) even with sumi-e ink...

    Regards,
    Loris.

     
  10. Photo Engineer

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    Loris;

    S/G as you call it :smile:D) actually sits more on the surface than platinum. You are correct. In fact, David Goldfarb posted some non-gelatin alternate prints here done with great enlargement of the scan. It was shown that the image sank down within the fibers of the paper as well as staying on top, and this apparently had an effect on both Dmax and on sharpness.

    You see, gelatin, as a binder, acts as a thickener and barrier to help reduce movement of the imaging material into the paper. OTOH, Pt/Pd in water can sink easily into paper. So, placing Pt/Pd in gelatin or some binder would change this. Unfortunately, I have not been able to try this as the Pt/Pd medium reacts with gelatin.

    Of course, sizing changes this drastically. So a gelatin undercoat and/or use of baryta paper might increase dmax of Pt/Pd.

    But, I have seen Baryta and gelatin both increase and decrease Dmax of Cyanotypes. There is a lot of work needed to find the best concentration of the ingredients to give any sort of improvement.

    Unfortunately, without using "tricks", you are stuck with a low Dmax with Pt/Pd, but then the long shoulder gives you wonderful depth into shadows.

    PE
     
  11. Photo Engineer

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    Loris;

    After thinking about this, I was wondering if you were aware of a measurement called Goniophotometry. With this measurement, you can examine Dmax and tone scale as a function of viewing angle. You can observe many changes in Dmax or scale just by tilting the measuring angle.

    In another case, you can use a spot meter and a standard viewing method to measure the curve shape of a print of any kind. When you step back to viewing distance, a print with a Dmax of 2.0 can often fall to 1.8 just due to the way the spot meter sees the print and this is related to the reflectance as a function of viewing angle. It is, in simple terms, Goniophotometry.

    A densitometer gives you idealized results, but a spot meter reading a print as you would view it gives a human's eye view. Much of the time, these two results are quite different.

    PE
     
  12. Ray Rogers

    Ray Rogers Member

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    A meter with gonads... (?)

    Does this mean a common 'spot meter' is a type of Goniophotometer?
    and that
    Goniophotometers read "angular" density
    while
    Densitometers reads "diffuse" density
    ?

    Do you have a picture of a Goniophotometer (?)
     
  13. Ray Rogers

    Ray Rogers Member

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    BTW,
    Which type of meter did you use to get a density of 1.9 with?

    As long as we are on this subject, can you clarify something for me?

    How can having a more reflective base (undercoat)
    and/or
    a more reflective surface (overcoat)
    increase D-Max?

    It would seem that the less light that got reflected... the higher the "density" would be... To me this is anti-intuititive.

    What am I over looking?
     
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  15. Photo Engineer

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    Yes and no.

    A spot meter can be used as a Goniophotometer if you can vary the angle of light or the angle of view.

    A densitometer can read several types of density but usually at only one angle (or group of angles) according to its design.

    There are some very good articles on Wikipedia on this Ray.

    I used Goniophotometry at one time to examine various tricks that could be played in surface reflection. I had 3 types of surface density as a function of angle, depending on tricks played. One was a rough ellipse, one was a rough circle (this is ideal BTW) and another looked rather like an onion with a pointy tip and a rounded body. It gave very high density when looked at straight down, but low densities off that angle.

    PE
     
  16. Photo Engineer

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    Ray;

    I own a Kodak and a TRX densitometer.

    A more reflective undercoat implies a heavier and less penetrable undercoat with more imaging material on top thus giving more internal reflections and thus raising dmax to a point at which it is clipped.

    If the support is too thin or the white material is too thin, then light from the back can reduce Dmax, but if the surface is very impenetrable, then everything is on the surface with strong back lighting which gives (with ultra high gloss) a high dmax, as is seen in some very thin digital papers which are almost translucent but have everything essentially on the surface.

    Hold up a sheet of Endura or CA that has been fixed next to a sheet of almost any digital paper with backlighting and you will see how more translucent the digital paper is.

    They have less TiO2 or other whitener, and it is close to the surface with glazing materials incorporated and there is little paper in the RC sandwich. FWIW, they may not use TiO2 or RC. IDK, just that the sandwich is rather thin.

    PE
     
  17. Ray Rogers

    Ray Rogers Member

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    Maybe it's just too early for me, :smile: but all I was able to grasp was that with a more refelective base, more light is reflected, and this leads to more internal reflection which leads to more loss of light able to escape the photograph and reach our eyes... thus darker and greater densities.

    However, it would also seem that greater reflectivity would not only boost the amount of internal reflection (and thus light loss) but also at the same time the amount of light that does actually escape; The two would seem to counter balance each other.

    Rather than layers,
    are there are additives that can be added to an emulsion that,
    by increasing internal reflections, might increase density?

    As far as I know, matting agents at least, tend to reduce both contrast and density.
     
    Last edited by a moderator: Jul 13, 2010
  18. Photo Engineer

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    Ray;

    If all of the emulsion is on the surface, less is reflected from the paper support. If it is half on the surface and half in the Baryta, then the dmax goes down, otherwise it goes up. But, it is a bell shaped curve so it goes up then down.

    Greater reflectivity can lower dmax and an example would be a very reflective RC paper in which the emulsion could not be absorbed.

    Additives are available to increase internal reflections. These are normally trimmer dyes to adjust speed and acutance dyes to adjust sharpness by reducing internal reflections. They are removed during the process.

    Matting agents do reduce contrast and density, but they are usually on the surface in an overcoat.

    PE
     
  19. Ray Rogers

    Ray Rogers Member

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    On Reflection...

    There may be additives to increase internal reflections,
    but I don't think they would be trimmer and acutance dyes :wink:

    As far as the rest goes however, I will just have to give it time to sink in I guess!

    Ray
     
  20. Photo Engineer

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    The silver halide and silver metal formed during development are very effective materials that cause (or form the basis for) increases in internal reflection both before and after exposure.

    PE
     
  21. Ian Leake

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    These two comments have got me thinking...

    With platinum there are no layers other than the Pt/Pd coating and the paper. Some of the coating soaks into the fibres of the paper whilst the rest remains on the surface; the amount that soaks in depends on the absorbency of the paper. And, of course, different papers have different thicknesses and degrees of whiteness.

    From what you're saying then, in order to get maximum Dmax one would need to use thick paper which doesn't absorb too much coating into its fibres. Am I understanding you right?
     
  22. Loris Medici

    Loris Medici Member

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    IME - putting all other factors aside... - thin papers usually give higher dmax than thick ones.

    Could be due the fact that:
    <SPECULATION>
    Thin paper can't soak all the sensitizer due less empty space (per constant area) in its stucture, keeping more of the sensitizer in its upper layers (which is what we actually need), therefore giving better dmax. Thick paper will soak the sensitizer more deeply (where it doesn't fulfill our needs - leaving less of it in its upper layers), therefore give weaker dmax. That means, we'll have more sensitizer per paper volume with thin papers, resulting in higher dmax - keeping coating solution volume per area constant...
    </SPECULATION>

    Just some food for thought.

    Regards,
    Loris.

    P.S. I'm not saying we need sensitizer "on" the paper (that will wash down the drain in processing steps), we need it "in" the upper layers of the paper!


     
    Last edited by a moderator: Jul 14, 2010
  23. Photo Engineer

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    Loris;

    With Pt/Pd, you are absolutely correct. OTOH, depending on paper type, the opposite may take place with Silver Halide in Gelatin.

    PE
     
  24. Ian Leake

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    I'd speculate that it's more about the rate at which the paper absorbs coating rather than its thickness per se. For example Buxton (thin paper) absorbs the coating quite easily (and it can absorb a lot of it if you want it to), whilst Arches Platine (thick paper) tends to keep the coating on the surface.
     
  25. Ian Grant

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    Ian, I'm more interested in why you asked the question.

    I was given an exquisite Palladium print on Monday, we compared it to a Jorge Gastreano original, and close by where Fay Godwin & John Blakemore originals as well.

    The Dmax of Jorge's Platinum print and the Palladium print aren't visually much different but the tonality is.

    Back in the late 80's I remember discussing with Fay Godwin going on a Platinum/Palladium workshop, we both decided not to for similar reasons at that time, mainly volume of work. Also a distraction from ongoing projects.

    I'm off to the South of Turkey to learn Plat/Palladium printing end of the month :D

    Ian
     
    Last edited by a moderator: Jul 14, 2010
  26. Kirk Keyes

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    I think print color will have a big effect here too. Warmer tones with equal reflection density are going to look less dense than more neutral tones.