Re: Gum problem(s)

On Fri, 2 Dec 2005, Tom Sobota wrote:

>> Well actually, I always register a gum print on the light table, viewing
>> through the negative and the new coat of emulsion to the coat beneath (tho
>> it doesn't work very well over yellow, it does fine over red, and even fine
>> details can be read (tho I don't know about newspaper -- maybe the print
>> was larger in those days?). Anyway, I just assumed they put the paper on
>> the light table & stuck the newspaper under it. (Uh oh, their "light
>> tables" were vertical, using sunlight -- hmmmm.)
>
> This is interesting. I use register pins, well, actually a pair of wooden
> pegs I 'built' myself, inserted in the contact press, which is also
> self-made, no vacuum, but works surprisingly decently.

I gave up register pins for several reasons -- first, I don't use a
contact frame, but 2 sheets of plate glass, which permits larger sizes, &
overflow at the sides for really large sizes -- and gets better contact
(at least for me).

Second, in a large print, if the paper has squiggled a bit out of shape,
you have to register from the edges with register pins, leaving maybe a
buckle, or like that, in the middle. With register by eye, you can
register from the middle, so that any fumpfer can be at the edges where
it's not so conspicuous... may even give a softening, feathered edge
(framing) effect. Not to mention that the damn little things (the pins)
are always falling into hidey holes, or just going out to lunch.

But then your paper probably doesn't behave badly. It probably knows who's
in control.

> What I register on the light table are the negatives, before punching the
> holes in them.

Maybe it's the punching makes them behave.

> I would have thought that registering a coated, thick paper on a light table
> is no easy task. But you do it, eh?

It's easier... Just, as I say, don't start with yellow. I can also mark
a light pencil line at 4 corners of the neg to give the gist to start
with. I learned this by the way from a student... a real space cadet who
just did it... I don't do it with the UV bulbs of course, but on the light
table. Even with the UV bulbs however, it's safe for the print. (I've
tried exposing the print through the back to fill in some blank spaces --
an hour on the BL bulbs through the back still made no density.)

But I anyway wouldn't want to stare into the UV bulbs, which you'd be
doing if you registered over them.

> What seems to be vertical these days are the newspapers. I mean, I read
> almost all the news on Internet, and I'm hardly the only one. Perhaps we
> could reach everlasting fame in gum-world adapting the method for a computer
> screen :-)

Someone in the very early days of the list announced his
"video-bichromates." He stuck coated paper on the monitor, exposed it
that way & developed. (Was it Alan Janus?)

> In a digital negative you have actually color density gradations in the dots,
> it's not quite the same as in halftone. But we are speaking of transparency
> in the coat, not in the negative?

I'm talking about the dot printed by digital and /or halftone neg. It's
going to be either on or off. Either hard or not there -- if there, a
fully exposed or relatively solid dot (as Kodak used to show in schematics
when it cared). But light tones from a continuous tone negative are very
delicate because they're lightly or partially exposed areas -- so they'll
be soft and wash off at a glance.

With dot or pixel negs, you get light tones by making the dots smaller
and/or further apart... but each dot is more or less fully exposed, hence
relatively stable. Which is why gum can be a lot easier to print with
digital negs, once you adjust.

Judy
Received on Sat Dec 3 00:27:47 2005