Re: tonal inversion and pigment loads

Katharine,

No, I'm not thinking silver at all. For me now, thanks to you amoung others,
I understand that the amount of pigment you put in a mix (as you said)
determine your Dmax (maximum optical reflextive density), in other words the
print can not be "darker" then the maximum concentration of pigment that can
be capture by the cross-link gum. How many step will show on a step tablet
print, well that is mostly dependent on exposure but many other factors or
variables come into play.

If you agree that gum (+ dichro of course) gets cross-linked in a manner
proportional to the amount of light that hits it and that the amount of
captured pigment is proportional to the amount of cross-linking.formed. Then
there should be as many step as there are distinct areas of varying density
of cross-linked gum.

Now, if you look at Tom experiment again
http://usuarios.arsystel.com/tksobota/Inversion-1.jpg, I think we can say
that he used the same "mix" for all 3 sample and unless my eyes are playing
tricks on me I can clearly see that each sample as a different number of
steps showing on them (excluding the inversion). The major contributor to
these changing number of steps is exposure.

Yves

----- Original Message -----
From: "Katharine Thayer" <kthayer@pacifier.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Saturday, January 28, 2006 3:54 PM
Subject: Re: tonal inversion and pigment loads

> No, if the particular mix you're using prints four steps, then that's
> the four steps you'll get, no matter what your negative is capable of
> doing. You're still trying to print gum as if it were silver; it
> doesn't work.
> Katharine
>
>
>
> On Jan 28, 2006, at 9:20 AM, Yves Gauvreau wrote:
>
> > Katharine,
> >
> >
> > I plead guilty, hope that's correct, as I and many of us here do
> > all the
> > time we speak about things and think about others without giving much
> > details. Here we where talking about step-tablets inversion (2) and
> > in my
> > mind I was thinking of an actual negative where the Dmax would be
> > appropriate for gum printing. In others words no 17 steps of dark
> > useless
> > tone.
> >
> > Regards,
> > Yves
> >
> >
> >
> > ----- Original Message -----
> > From: "Katharine Thayer" <kthayer@pacifier.com>
> > To: <alt-photo-process-l@sask.usask.ca>
> > Sent: Saturday, January 28, 2006 12:20 AM
> > Subject: Re: tonal inversion and pigment loads
> >
> >
> >
> >>
> >> On Jan 27, 2006, at 7:44 PM, Yves Gauvreau wrote:
> >>
> >>
> >>> Katharine,
> >>>
> >>> I should have explained myself more clearly on this. If you look at
> >>> Tom
> >>> image again, you'll see that as the exposure increases, the number
> >>> of "paper
> >>> white" step(s) gets lower and lower suggesting that the lowest
> >>> exposure
> >>> (time) must not be allowed to invert at all, otherwise you get
> >>> what is
> >>> called "inversion" stains (for now). I think we can all agree on
> >>> that.
> >>>
> >>
> >> Actually I can't, because I'm not sure what you are saying. Are you
> >> saying that the answer is that you should expose so long that you
> >> push the print tones all the way up to 21 so that there's no room for
> >> stain, making all the steps from 1 to 17 black? And then just develop
> >> for the next month to get rid of the tone back down to the four
> >> actual tonal steps? This doesn't seem to me a reasonable thing to
> >> do. And maybe that's not what you're saying.
> >>
> >> To me the place in the middle where there's less tone, is just the
> >> end of the normal tonal scale, the lightest highlights, and then the
> >> stain starts. The hardened gum in the lightest steps forms a bit of
> >> a resist to the stain, less with each ascending step, and so the
> >> stain gets darker with each increasing step. That's all it is.
> >>
> >>
> >>>
> >>> I'm not sure there is away to get ride of the "inversion" stain
> >>> otherwise
> >>> Tom would have taken them out and this wouldn't even be a problem
> >>> otherwise.
> >>>
> >>
> >> Well, you can't take it out of the thing you've just made, but you
> >> can sure fix it for the next time, by making sure that you remedy the
> >> thing that is causing the stain; either the paper needs more sizing
> >> or the pigment load needs to be adjusted. I keep taking this page
> >> down but someone keeps wanting it back up, so here it is again, the
> >> PV 19 inversion I showed a couple of weeks ago. By reducing the
> >> pigment load by 1/3 and reprinting, I made a nice magenta layer of a
> >> tricolor, shown directly above the inversion, although still just a
> >> touch too pigmented. In other words, it's not that hard to fix an
> >> inversion, just fix the problem that's causing the stain.
> >>
> >> http://www.pacifier.com/~kthayer/html/tricolorfun.html
> >>
> >> And there's another example on my pigment stain page, in the tonal
> >> inversion part: I show some tonal inversions with burnt umber, and
> >> then there's a link to a similar image of the same subject, printed
> >> with less burnt umber, which prints a perfect tonal scale with no
> >> stain, to show the remedy for the inversion. If you don't want to
> >> read the information, just scan the second paragraph under the
> >> inverted images for the blue link "here." to see the comparison
> >> image.
> >>
> >> http://www.pacifier.com/~kthayer/html/stain.html
> >>
> >> The point being that fixing inversions is a snap, just fix the stain
> >> and the inversion goes away.
> >>
> >>
> >>>
> >>> The step tablet should be opaque to light for steps and nothing
> >>> should print
> >>> above the first "paper white" step.
> >>>
> >>
> >> Yes.
> >>
> >>
> >>> The observation we all made is that Tom
> >>> test shows a relatively uniform tone above these "paper white" steps
> >>> whatever the exposure (in these cases).
> >>>
> >>
> >> And that tone, is stain.
> >> Katharine
> >>
> >
> >
>
Received on Sun Jan 29 10:15:30 2006