Re: Carbon Printing UV/Cool White
s carl king (sanking@hubcap.clemson.edu)
Fri, 5 Jan 1996 16:45:29 -0500 (EST)
>
> >Nine (9) 1X5" strips of carbon tissue were sensitized in two sessions, using
> >five separate 5X7 trays. Easy was sensitized separately, using 3 ounces
> ^^^^^
> Each?
>
Yes, it was also easy, but I meant *each*. I have got to find a way to
edit these posting. When I write directly into the elm editor
on Unix I can't see typo errors on screeen, but when I edit
first on a word processor off unix and paste it in all sorts
of extraneous codes seem to be inserted. Help!
> >My experience with this tissue is that it is fairly high in contrast. After
> >all, that is 12 grams of pigment per 1000 ml of coating solution, including
>
> That is a rather significant part of the equation you left out! What
> percentage of gelatin in there, at what Bloom Index?
>
The gelatin percentage was 9%, with a 175 Bloom Index. Morevoer, this
gelatin product is one I have been using for more than a decade. I use
100ml of coating solution per 11X14" tissue. (Sorry, I know these
mixed measuring systems must drive metric folks wild!)
>
>the color does
> >introduce a variable that could have been eliminated by the use of a
> >nuetral black tissue.
>
> The color is important indeed and even "neutral black" has to be defined.
> At one point I had 17 different types of black pigment in my atelier here.
> They varied tremendously in terms of characteristics.
>
Well, let me turn the worm. Were they all made with the same gelatine, at
the same percentage solution, with the same coating solution per area?
I make carbon/carbro tissue in a wide range of tones (lampblack, ivory
black, warm-brown, purple-tone, warm-red, etc., etc.) and certainly there are
some differences in contrast with my specific working conditions. However,
from previous experiences I know that the printing characteristics of the
particular tissue tested, which I have been making since 1992, are not
significantly different from other more neutral black tissue I use.
>Another very important variable is the thickness of the coating. Pretty
> hard to judge with hand coated techniques.
>
If you were to plot the densities from my tests you will find a
number of spikes and downs which are the result of small incosistencies
in my hand-coating techniques. Still, these are on the order of .03-.07
at most and could certainly not invalidate the major findings of the
reported tests.
Sandy King
Sanking@hubcap.clemson.edu