Re: Opacity of digital negative substrates, was Re: Gum a la Sam Wang

From: Tom Ferguson ^lt;tomf2468@pipeline.com>
Date: 11/24/03-09:23:52 AM Z
Message-id: <35C20866-1E92-11D8-87AA-000502D77DA6@pipeline.com>

My testing method is a bit simple compared to Mark's (Sam's). But, I
too found Pictorico gets a longer basic/MBT exposure than my standard
silver films. I've tested Plat/Pallad, Kallitype (on cloth and paper)
and Cyanotype. I haven't used Pictorico and gum (yet). Nothing huge or
disturbing, about 1/2 stop more time.

On Sunday, November 23, 2003, at 10:32 PM, Ender100@aol.com wrote:

> <SNIP>

> I took the Stouffer step tablet and laid it over the edge of a piece
> of clear Pictorico film in such a manner that the edge of the strip of
> Pictorico bisected the Stouffer step tablet.  I then made an exposure
> of roughly 2-3 times what I thought was was my ballpark exposure for
> this mix of PT/PD on the given paper with a NUARC—to make sure I would
> end up with at least two steps merging.  Once developed and dried, I
> examined the test print with my own eyeballs and looked for the point
> where two dark steps of the printed Stouffer merged.  I found it.  I
> celebrated.  I even double checked with a desnitometer appropriately
> set to reflective mode.  The merging of the two steps was exactly one
> step lower for the portion that was also covered by Pictorico—in every
> case.  I should add here, of course, that this was the infamous
> Stouffer #T2115 21 Step Sensitivity Guide (granted, the uncalibrated
> version, which costs more), which measures exactly .15 log
> transmissive density per step give or take a lumen or two.
>
> At least for PT/PD and God only knows what other alt process, I would
> have to say that I am convinced beyond a shadow of a doubt and I would
> even bet the life of my first-born....well maybe my second-born....
> that clear Pictorico film measures about 1/2 stop or .15 UV density.
> <SNIP>
--------------
Tom Ferguson
http://www.ferguson-photo-design.com
Received on Mon Nov 24 09:24:14 2003

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