Re: Dots of gum?

Hi Ryuji,

You are correct, I didn't read his post closely enough—he's printing a
continuous tone negative through a screen so it is a hybrid method contone/screen,
which may still make my assertion half way valid. ;)

The other issue is that when printing with larger dots doing full color with
gum, a number of people have reported that a coarser screen seems to give more
vibrant color since the dots don't get as "muddled" as they do with smaller
dots. At the same time, an overlay of dots of different colors doesn't look
as coarse as one would think because of the overlapping. A similar effect is
seen when printing on matte papers with inkjet, where using 720 ppi may work
better than 2880 on some papers.

Anyway, it makes sense to me, but I'll have to try it to confirm it.

Best Wishes,
Mark Nelson
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In a message dated 2/12/05 4:44:06 PM, rs@silvergrain.org writes:

> From: Ender100@aol.com
> Subject: Re: Dots of gum?
> Date: Sat, 12 Feb 2005 17:09:07 -0500 (EST)
>
> > Do you think it might also be that with a screened negative, you are
> > printing "black and white dots" rather than continuous tone?  Thus
> > each dot receives the same amount of full exposure to harden it.
> > Increased "Tone" is achieved when the dots are placed closer
> > together in the screened negative.
>
> He said he prints through a halftone screen, not halftoned negative.
> So his exposure is still continuous tone with fixed size grating.
>
> In real, old fashioned way to make halftone negative is to use
> halftone screen somewhat off the negative, combined with right lens
> and aperture, so that each "dot" on film has highest exposure at the
> center and the exposure falls off as the radius increases. The film
> often receives nonimage flashing on top of the imagewise
> exposure. Then the film thus exposed is processed in classic lith
> developer consisting of hydroquinone as the sole developing agent with
> little sulfite. This type of processing gives very high contrast and
> reasonably hard dot quality. But more recent lith films and developers
> incorporate contrast enhancing agent (hydrazine compounds) and these
> can be processed in rapid access type system, while offering improved,
> rock solid, dot quality. Of course all these are obsolete with digital.
>
> There were also some lith films preexposed with grid patterns so that
> halftoned negative could be made with imagewise exposure only. Oh what
> else... there were lots of stuff in this area but no more...
>
Received on Sat Feb 12 21:16:26 2005