Re: Could someone summarize that gum up or down discussion?

>
>Tell me that NO ONE is saying that you cannot achieve this tonality
>with gum from front exposure, please please please. I fear we are
>revisiting the arguments around Pouncy 150 years ago that have been
>severely disproven since.
>
>Tell me, instead, that you all are just finding a way to
>successfully print contone on plastic? If so, kudos to Sandy, Marek,
>and Katharine for pursuing this idea. The bummer may end up being
>that you can only do this one coat because the next coat you will be
>exposing through the previously hardened layer which in turn will
>hold back light in the shadows...or so it is said, as I have not
>done this so forgive me in advance if I am passing on a myth.
>
>One last thing, since gum is a short scale process, making a digital
>negative curved to that short scale will therefore print a fully
>tonal image, so personally I feel that a lot of the problems with
>gum printing in the 1800's were due to not having the right negs for
>the process. If they had overexposed and underdeveloped their
>negatives back then to contract the zones they would have avoided a
>lot of this "gum doesn't do halftone" stuff...
>
>But how exciting that the community of the list is working together
>from all parts of the globe to hash out this stuff!!
>Chris

Chris,

I don't know what others are saying and I don't pretend to speak for them.

I have never said that it is not possible to get very good shadow
density ( high Dmax) and a long tonal scale with gum when printed the
traditional way. But, and this is what I am saying, it is not
possible to get both very good shadow density and the long tonal
scale with a single coat and a single exposure. If you want both very
good shadow density, and a long tonal scale, multiple coats and
printing are necessary. Now, if anyone disputes this statement it is
almost certainly because his/her understanding of shadow density is
very different from mine. The plain and simple fact is that you can
not load a single gum coating with enough pigment to give real high
reflected Dmax. If you do, the coating just flakes off the top. A
digital negative with the right curve and contrast is not going to
help very much to prevent the flaking, IMO.

The obvious advantage of printing through the back on a gum coating
is that you should be able to get a very high Dmax (should be
comparable to carbon where a reflected log density reading of 2.0
or more is obtainable), and at the same time a long tonal scale. And
you will be able to do this with a single coating and printing.

In carbon printing we have both direct carbon (which is similar to
gum printing) where we exposed from the top, and carbon transfer,
where we expose from the top but transfer the image to another
surface to take advantage of top down hardening.

The experiments that have been carried out demonstrate that it is
possible to make prints with gum using either the basic mechanism of
direct carbon, or that of transfer carbon.

My comments are meant to apply only to monochrome gum. All sorts of
other considerations apply to color gum.

Can a gum exposed from the bottom on a plastic support be transferred
to paper? I don't know. Gelatin images can certainly be stripped
from plastic so I believe there is reason to believe that the same
could be done with gum.

Sandy
Received on Sat Apr 15 20:04:45 2006