Digital BW, The Print

Ditto, seems rather strange.  Why didn't you just print Piezo on EAM?

Also...with regards to Steadman's note....it is absolutely critical that
prints are made at the same time because of natural warming that occurs...at
least with Piezo (don't know about the MIS inks).  Starting a fade at Print
Time = 0 and Print Time = 2 weeks will certainly yield different results.

Robert

On 10/17/01 7:21 AM, "Cathy Van Berg" <vanbergc@...> wrote:

> Let me make sure I'm understanding this correctly...
> 
> You printed Piezo and MIS VM/VM X3 on different papers for this test?
> If that is true, then you cannot draw valid conclusions by comparing
> what I see as apples and oranges... You may say that for a given
> paper, these inks fade x amount, but you cannot compare them to each
> other. If it was not your intent to compare fading and warming between
> the inks, then that was not clear to me...
> 
> Thanks,
> Cathy
> 
> 
> 
> --- In DigitalBlackandWhiteThePrint@y..., "Paul Roark"
> <paul.roark@v...> wrote:
>> In the latest fade test series, I put test strips of Piezo on Hahnemuhle
>> German Etching, MIS VM (nc curve) on EAM, and an experimental
> variable-tone
>> called VM X3 that prints with the same curves as MIS VM (nc curve).
>> 
>> I measured fading as a percentage of the starting value and warming
> as the
>> change in the difference between the RGB red and blue channel
> measures.  The
>> test strips were scanned into Photoshop with an Epson 1600, and the
>> Histogram tool was used to make the measurements.
>> 
>> 0% (paper white) warming:  EAM (2 samples) 2.4 & 2.3 units;  German
> Etching
>> 0.6 units.
>> 
>> 50% patch measures:
>> 
>> Piezo on German Etching -- Warming = 10.3 units,   Fading = 9.2%
>> 
>> MIS VM on EAM           -- Warming = 9 units,      Fading = 6.9%
>> 
>> VM X3 on EAM            -- Warming = 3.1 units,    Fading = 5%
>> 
>> Note that most of the warming had taken place by the 100 hour mark.  The
>> fading was also fastest at first, but it continues much more so than the
>> warming.
>> 
>> The fading of the 90% patch needs to be mentioned.  I measure the
> 90% patch
>> as opposed to the pure 100% patch to see what the shadows will be doing
>> because it may indicate whether there is a negative interaction
> between the
>> black ink and something in the midtone inks (and, of course, the
> paper is a
>> huge factor that affects all the patches).  A number of people have
> noted
>> that some components, perhaps including dyes, can actually act as
> catalysts
>> in fading other components, for example, the black ink.
>> 
>> (Note that in my fader the light is intense, so the black patches are
>> undoubtedly warmer than the lighter patches.  This is probably also
> the case
>> in the "south window tests" and perhaps all accelerated fade tests.  One
>> would expect, therefore, to see more fading in the darker patches.)
>> 
>> To measure the fading of the 90% patch, I converted the mode to
> grayscale
>> and used levels to set the white and black points of the control
> strips as
>> accurately as possible.  The percentage of fading is a percentage of
> the 90%
>> control strip for each set.  (The MIS VM and X3 are about the same.)
>> 
>> 90% patch fading:
>> 
>> Piezo on German Etching -- 55%
>> 
>> VM X3 on EAM -- 18%.
>> 
>> Also of note, the Piezo 7000 black on the German Etching paper is
> slightly
>> darker than the MIS VM black on EAM printed with either the 3000 or
> 1160.
>> When the levels sets the Piezo/German Etching black on 100%, the MIS VM
>> blacks read 98%.
>> 
>> I have sent a Jpeg of the scans to Martin for inclusion in the Message
>> Related Files section of the forum.  I did notice, however, that the
> Jpeg
>> compression slightly affected the measures.  So, measuring those
> Jpegs may
>> result in slightly different readings than above.
>> 
>> Paul
>> http://www.PaulRoark.com
> 
> 
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----------------------
Robert Morrison
rmorrison@...

310-397-2704

4131 Bledsoe Ave.
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