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Author Topic: dMax, RC vs Matte: why?  (Read 2231 times)
hugowolf
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« on: September 22, 2012, 10:32:24 PM »
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I fully understand that mat papers will not give me the high dMax levels of glossy and lustre/satin/pearl RC papers. My question is why? What physical properties of the two types of media make this happen?

The question arose during a conversation this afternoon with a fine art print maker during an examination of some of her mezzotints, for which she had used a 75/25 mix of pigment and dye inks the dye ink to increase dMax.

I can understand the dye ink increasing the dMax, but why would a mat fine art paper invariably have a lower dMax value than an RC paper?

My initial reaction was that a mat paper would scatter the light more. But on reflection, that would seem have the affect of increasing dMax less light reflected back to the viewer would make it darker not lighter.

Any thoughts would really be appreciated.

Brian A
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darlingm
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« Reply #1 on: September 22, 2012, 10:49:27 PM »
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My understanding is that your initial reaction is fairly dead on.  Matte papers reflect light much more scattered, where gloss papers reflect more focused like a mirror.  If you went into a dark room and shined a focused beam on matte papers, the paper would appear about the same from whichever point of view you looked at it (assuming the beam didn't move.)  If you did the same on a gloss paper, you would see a bright reflection of the beam that would "travel" around the paper based on the correct angle between you and the beam.  The focused gloss reflection allows a pure black area to reflect less light than if it was on a matte surface.
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Mike Westland Printworks
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http://www.westlandprintworks.com (734) 255-9761
Ernst Dinkla
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« Reply #2 on: September 23, 2012, 08:31:56 AM »
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I can understand the dye ink increasing the dMax, but why would a mat fine art paper invariably have a lower dMax value than an RC paper?

Any thoughts would really be appreciated.

Brian A


With light reflecting scattered from a matte black surface the eye will always catch some light viewing that area while a light reflection from a gloss black surface is more a yes or no situation.

The explanation why a black dye gives a higher Dmax on matte papers than a black pigment ink is actually something I find harder to grasp. My theory has been that the coating/paper structure is impregnated by the black dye ink while the pigment stays more on top and forms a layer there. When light falls on dyed paper it is not all directly reflected from the top but goes more into the substrate and is there scattered within the structure and less light goes out again. Kind of drowning. This decade new ultimate black paints and surfaces have been developed and microscopic images of those surfaces show a kind of high peaks and deep valleys in between comparable to echo-free sound chamber walls.
http://news.bbc.co.uk/2/hi/science/nature/2732487.stm
http://en.wikipedia.org/wiki/File:Radio-frequency-anechoic-chamber-HDR-0a.jpg


--
Met vriendelijke groet, Ernst

340+ paper white spectral plots:
http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
update july 2012: Moab changes, paper sorting by name





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hugowolf
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« Reply #3 on: September 24, 2012, 07:09:40 PM »
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A thanks to both of you, I see the scattering in a different light now. (Soory, Couldn't resist.)

Brian A
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darlingm
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« Reply #4 on: September 24, 2012, 09:22:09 PM »
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A thanks to both of you, I see the scattering in a different light now. (Soory, Couldn't resist.)

Brian A

Lol, nice.

It suddenly hit me today what's happening if fingers touch a dark matte black area, and it "scuffs".  I've always figured it was the oil causing an issue, but it became clearer to me today that I think what's happening is it's turning the area touched toward a gloss finish, so the black appears lighter and there's sheen to it.  Seems to make sense, because I see the "scuffing" when angled properly with a light, but if no light is angled to bounce off a gloss surface properly to my eye, I don't see the "scuffing" as much.
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Mike Westland Printworks
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Paul Roark
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« Reply #5 on: September 24, 2012, 09:47:20 PM »
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In my home I have two 50 watt (or equivalent) spots on a print, as well as the usual room light.  The ceiling is white, walls are light, windows are south facing, and the print is on the east wall, so we're not looking at any reflections of windows in the glass or off the print.  When I put a glossy and a matte 100% black print on the wall, under glass, and measure the dmax with my 1 degree spot meter from where I would be looking at the print, the matte paper wins the race; it has the higher visual dmax.

It's all about reflections and the type and intensity of the light.  Glossy prints do not have a higher visual dmax in the real world in many normal interior display settings.  The spectrophotometers have, in effect, perfect lighting and no reflections.  There gloss prints win easily.  In direct sun, its the same story.  On the wall in typical home or office display, matte prints often if not usually will have a higher visual dmax.

With snapshots, you'll see people moving them around to get the reflections out of the way.  That's hard to do with a print on the wall.  So, my practice is to use matte under glass for wall, fine art display, but use glossy (B&W dyes usually) for brochures, cards, and snapshots.

Paul
www.PaulRoark.com

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Alan Goldhammer
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« Reply #6 on: September 25, 2012, 07:53:56 AM »
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Paul, thanks for this post.  It's always interesting when something counter-intuitive is discussed here.  It all depends on the factors you list, though I would be a little careful in stating, "... glossy prints do not have a higher visual dmax in the real world in many normal interior display settings."  Most modern offices down in my area (Washington DC) have intense halogen lighting and I know from the experience at my former employer where they have a hallway gallery of my prints that the particular lighting there favors the glossy over the matte prints.  The interior reflections cannot be controlled in the manner that you note.  That being said, this is a good reason not to forsake printing on matte paper since Dmax measurements from a spectro can be misleading in terms of what will happen in the "real" world.

Alan
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robgo2
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« Reply #7 on: September 25, 2012, 06:02:41 PM »
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In my home I have two 50 watt (or equivalent) spots on a print, as well as the usual room light.  The ceiling is white, walls are light, windows are south facing, and the print is on the east wall, so we're not looking at any reflections of windows in the glass or off the print.  When I put a glossy and a matte 100% black print on the wall, under glass, and measure the dmax with my 1 degree spot meter from where I would be looking at the print, the matte paper wins the race; it has the higher visual dmax.

It's all about reflections and the type and intensity of the light.  Glossy prints do not have a higher visual dmax in the real world in many normal interior display settings.  The spectrophotometers have, in effect, perfect lighting and no reflections.  There gloss prints win easily.  In direct sun, its the same story.  On the wall in typical home or office display, matte prints often if not usually will have a higher visual dmax.

With snapshots, you'll see people moving them around to get the reflections out of the way.  That's hard to do with a print on the wall.  So, my practice is to use matte under glass for wall, fine art display, but use glossy (B&W dyes usually) for brochures, cards, and snapshots.

Paul
www.PaulRoark.com



I agree with this analysis.  The reflections off the shiny surface of gloss paper subtract from the measured Dmax, resulting in a lower apparent Dmax.  With carefully controlled lighting, it may be possible to minimize this effect, but that is often not possible.  In general, I find that there is a tendency for many of us to overrate the importance of Dmax and paper whiteness.  The human brain interprets very dark areas as black and very light areas as white.  In terms of perception, that outweighs measured blackness and whiteness.

Rob
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Paul Roark
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« Reply #8 on: October 13, 2012, 11:27:22 AM »
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Here is an amusing addition to the above discussion regarding the importance of the reflective nature of the medium to the measured dmax.  I measured the "density" of a normal glass mirror with my spectro.  The mirror has a density range of 1.65 to 1.75!  Not a bad "dmax" for an object that reflects nearly 100% of the light that hits it.

Next time you think the relative glossy and matte dmax numbers are comparable, remember this experiment.  it's all about reflections and lighting.  They are different media. 

I use matte for interior B&W print display, and I think it typically has a higher visual dmax in those situations.  I use glossy paper for my brochures and cards, where they are hand held and the viewer simply moves them to avoid reflections.  They may also be viewed outside in sunlight where the very bright point source light -- the sun -- makes matte black look gray.

Note also that the density to percentage of light reflected is very non-linear.  All of the dmax numbers we see are closer to each other than might be expected.  See the graph at http://www.gravurexchange.com/gravurezine/0804-ezine/ploumidis.htm

An additional factor in display is that, I believe, once the viewer sees a reflection off the print, particularly if it is not dry mounted such that the viewer will likely see a waviness with gloss paper, the illusion of looking at a three dimensional scene is destroyed -- it's just a piece of paper.  Matte paper allows simple and more archival mounting, for example simple tape hanging,  without the risk that waviness in the print will be observed.

Paul
www.PaulRoark.com
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