Re: Single coat Gum Print..Negative aspects

From: Judy Seigel ^lt;[email protected]>
Date: 07/01/05-01:43:17 PM Z
Message-id: <>

When I logged on today, the first subject line to meet my eye was
"Powerful Enlargement." I thought of course it was a new photographic
technique. This proved not to be the case... and the info was not a great
deal of use to me, personally. However, I think I may have some useful
info in the matter of one coat gum -- having spent a fair share of my
time on earth pursuing it.

Firstly, I find little relationship between a negative for one coat and a
"general" gum negative. Because it's useful (although not essential) when
printing multicoat gum to give successively longer exposures (often in
different colors -- I myself use tri-colors for fake "real" color prints)
in which case I find a negative of from say 7 to 10 21-step steps works.

But any of them depend on variables of mix and paper, size, development et
al.,to figure the number of steps to give the negative. So for one-coat
gum you don't start with the negative and try to print it, you start with
a print from a 21-step, and count the steps you're getting and make the
negative accordingly. How to do that even without a densitometer is laid
out in Post-Factory #1, even illustrated -- the part about the light table
and the white cards with a hole in them. (Chapter starting page 37.)

If you're only getting 3 or 4 steps, for instance, try noodling the mix --
maybe increase the ratio or strength of the dichromate, or try somewhat
weaker size, or slightly rougher paper. (Note: longer exposure and longer
development, up to 24 hours, can often squeeze out an extra couple of
steps.) What you also want of course is a pigment with good covering
power because you need to get as much d-max as possible with one layer.
Here a cheap paint will probably do you in, because it's going to be
attenuated with fillers and you can only use just so much. Of course some
pigments have more "covering power" than others. For instance ivory black
is weak, indigo (whatever pigment they're using) is usually very strong. I
wouldn't want a blue portrait, necessarily, but you can kill that blue
with a strong red -- if memory serves, there's a good perylene maroon. But
the generic names are useless here... you have to test the paints or at
least see the swatches.

If you have to pile in too much paint, you won't get a nice scale, because
the emulsion will flake off the highlights. (There's a lot about these
controls & varuiables also in P-F #1, "Annals of Gum Control, part 1.")

There are also a couple of articles specifically about one coat gum in P-F
#6, including "Serious One-Coat Gum Printing" with a much more extended
version of the above, illustrated. (Hint:try gouache, since you don't have
to worry about transparency. You can get a bigger bang of D-max with
opaque gouache.)

There's also a rundown on Bernie Boudreau's method in #6 ("Gum Printer to
the Stars"). He uses a size of one part gesso, one part gelatin (as I
recall Katharine uses a related mix) that can do wonders in getting a
really strong single coat.

I would repeat, beware of "rules" about the "right" negative for gum.
Folks are often making exquisite, even ideal gum prints -- but they're
talking about what works for THEIR variables, colors, paper, development,
size, whatever -- possibly yours, but the match may not be your best.
The real rule is that, for one coat gum the ideal negative has the number
of steps your conditions will print.

(I began that first gum article with two opposite "rules" from two
"classic" "authoritative" "iconic" gum advisories, that I tactfully leave
nameless here.)

But it's a fascinating endeavor and wonderful when you succeed... even if
you don't get the one coat perfect (and colored pencil will cover a
multitude of sins), you will probably learn gum printing in the
endeavor... And one more thing, "Sorry Keats, Beauty isn't always Truth
(especially in gum printing)" also in P-F #6, has 18 "rules" of gum
printing and the actual facts, at least as shown by 21-step in this
particular latitude. The Conclusion is incontrovertible: "Knowledge is
incomplete and provisional. Art is forever."

PS to David: Have you tried a negative with very open shadow steps
relatively close together (for that richer background with less detail)
and steeper highlights ???



On Thu, 30 Jun 2005, davidhatton wrote:

> I need to know what an inverted negative for a successful single coat gum
> print. I don't need to see the finished product (thought that would be nice)
> I just need to get a 'feel' for how the thing should look. I don't really
> understand when people say ' use a negative that would print well on grade
> two paper' or 'the density range should be log 1.17' etc. These things mean
> nothing to me as I am a moron. Could someone take pity on me, decipher this
> request and post such an image somewhere on the web? I have already used
> enough gum to effect futures for the next million years..
> Thanks in advance,
> David H
> --
> Internal Virus Database is out-of-date.
> Checked by AVG Anti-Virus.
> Version: 7.0.323 / Virus Database: 267.8.0/27 - Release Date: 6/23/2005
Received on Fri Jul 1 13:43:29 2005

This archive was generated by hypermail 2.1.8 : 08/25/05-05:31:50 PM Z CST