Judy Seigel (jseigel@panix.com)
Wed, 13 Oct 1999 20:06:03 -0400 (EDT)
On Wed, 13 Oct 1999, Wayde Allen wrote:
>> ....If you want a one-coat gum, then you have to
> > compress -- no more steps in the neg than gum will print at one time (like
> > maybe 6 or 7). But if you plan several coats, you can use any kind of neg
> > you want -- getting more of the range with each coat -- or actually the
> > other way around: start with the whole range in a light color, then print
> > less with each following coat, each a bit darker & shorter range than the
> > one before, finishing with shadow detail.
>
> This has always confused me a bit. I can see printing a negative for the
> shadows (clearest areas in the negative) since those would take the least
> amount of exposure. What bothers me is that the highlights (darkest
> regions in the negative) need the most exposure to print. It has always
> seemed to me that printing the highlights should make the shadows overly
> dark.
Which by the way is one reason those pundits who give you "formula" for a
gum print are so wrong. Emulsion is variable in all sorts of ways... & for
each coat (should you so desire).
You give first coat long exposure in a not too thick coat of whatever
color you want your highlights to be, then beef up the shadows etc. on top
of it. One way to be sure the shadow tones don't bury the highlights is to
use less dichromate (say 1 part gum to 1 part dichromate or even 2 to 1
instead of 1 to 2), so the mix is less sensitive, making it contrastier,
that is, the highlight areas will wash away.
Some people use 2 or 3 different negatives, from flat to contrasty, but
I've found that a big nuisance and in my experience not as good -- tho
others swear by it (maybe people who can keep better track of their
negatives than I can).
> I guess that printing the highlights with a lighter pigmented coat
> (or maybe even a thinner coat) would help. Still, I worry about making
> the print too dark this way. How is this prevented?
When you say "print too dark", I take it you mean choking up the
highlights -- that's in the mix and exposure, as above. I'll add by the
way that I don't find darker color takes *appreciably* more exposure...
Remember, none of the coats in a multiple coat gum is as heavy by ANY
measure as for a one-coat gum. A crude rule of thumb (and of course the
exceptions are myriad and as you like 'em) would be, if quantity of
pigment for a one coat gum is 5, then quantity of pigment for a multiple
coat gum for first coat might be 2-1/2 and for subsequent coats 2 & 1.
I stress that those numbers are for *principle* only -- each negative and
color combination works differently. But the beauty of it is you can wing
it -- look at what you've got & add more or heavier coats, or develop more
strongly or brush out to get less in the current coat. But since
highlights are always *thinner* in the print, I don't see them easily
getting too dark... assuming the negative has a decent contrast range.
Of course this would be with continuous tone negative. A digital (or
halftone) negative prints entirely differently. I've mostly done digital
with color separations which is a whole other thing. The 3 colors get
about the same exposure, allowing only for *chemical* (actinic is I
believe the word?) differences in the pigment sensitivity. But digital is
EXTREMELY easy to develop to order -- those little dots are happy to wash
away without leaving the bald spots you can get by overdeveloping
continuous tone. I've done some digital also with single coat, but that's
not your question either. (I also reserve the right to modify digital
comments as I haven't done as much as I plan to ... and yes, in THIS
life.)
Gum printers of the world... Agree/disagree...????
Judy
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| Judy Seigel, Editor >
| World Journal of Post-Factory Photography > "HOW-TO and WHY"
| info@post-factory.org >
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