On Jul 12, 2006, at 2:53 AM, Loris Medici wrote:
>
> BTW, to all: How do you determine your standard printing time with
> gum?
>
> Since calibrating Argyrotype I determine SPT by overexposing a step
> tablet,
> then scan it, average the tone in the steps, change the mode of the
> file to
> Lab, create a new grayscale file from the Luminance channel and use
> the
> levels adjustment tool with the Alt key to locate the first black
> square.
> Then I make the necessary exposure time adjustment (by counting
> steps below
> the first black and reducing the exposure according to this) and
> retest
> (using the same step tablet along with the CDRP) to see if
> everything's
> right and to determine the negative color. It was surprising to see
> that the
> density I was choosing with the former method (visual inspection of
> the step
> tablet) was often 1-2 steps off (overexposure - I was often
> choosing an
> exposure time which causes solarisation = less dmax)... What would
> be your
> comments on this?
>
Loris, I'm sorry, this makes no sense to me at all. Overexposure =
solarization = less DMax? This is GUM you're talking about? In my
gum universe, all overexposure does is block up the shadows higher,
requiring a longer development to unblock them, but in all my years
of gum printing, I've never seen solarization or loss of DMax as a
result of overexposure.
Katharine
Received on 07/12/06-10:48:33 AM Z
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