From: Judy Seigel (jseigel@panix.com)
Date: 02/03/00-01:00:32 AM Z
On Wed, 2 Feb 2000, James Romeo wrote:
> As you know I receved my copy of " Spirts of Salts " I have ben lookin
> threw it but a few things bother me. A exp on gum under shopping list
> they say buy a small bottle or glue Don't bother with the traditional
> gum arabic it iss difficult to prepare and needs a preservative to
Uh Oh... we ran a thread on this on the list about 90 years ago, and in my
experience it's quite wrong. As far as I know, the "glue" referred to is
Gloy, which is essentially PVA with some color and other proprietary
ingredients, made by Henkel, replacing what used to be called
"mucilage". It's not sold in the US.
I have however tested it EXTENSIVELY... I myself could NEVER get it to do
an autodevelop continuous-tone gum, but only quite high contrast. I have
however seen prints from (as I recall it was Larry Shapiro in CA, they're
in the file, I could check if anyone insists), who did get continuous
tone, albeit no high tones. Gloy is probably fine for certain styles of
gum printing, ie, several coats with spray or brush for each one, but as
noted not for delicate gradations, let alone one-coat prints. It was
generally agreed on the list at the time that gum arabic does print more
subtly, although the English (ie., Terry King) argued for Gloy... partly
from habit perhaps, or perhaps lithographers gum isn't the same there.
The business about gum arabic being difficult to prepare is also off, tho
if you mixed it from dry gum (as many do to adjust the viscosity) you
would have to add a preservative -- thymol, glyoxal, formaldehyde -- we've
given amounts on the list. But in this country certainly, most gum
printers buy gum arabic, called lithographer's gum 14 degrees baume
(that's the viscosity) by the gallon already mixed with the preservative,
which keeps indefinitely and costs $16 per GALLON. See for instance
Philben in Post-Factory Sources & Services. Also Daniel Smith, in fact,
just about any lithographer's gum. A gallon is pretty much a lifetime
supply unless you're doing murals... I'm on my second gallon this
lifetime, the first lasted 15 years and did not change in that time. (I
don't do murals but do tear up a lot of prints.)
The 5-ounce bottle of gloy cost one and a half pounds 5 years ago, or $60/
gallon if bought in that size, tho presumably there are larger containers.
I repeat however that no printer I know of has gotten real detail and
delicacy from the PVA -- which can, incidentally be bought in the US. Mike
Ware, who was testing the PVA himself (and as I recall NOT to his
satisfaction) told me the type, I'd recognize the term, probably have in
notes somewhere, tho pursuit hardly seems worth the candle (to coin a
phrase).
Mike's reason for avoiding Gloy, incidentally, was the problem with basing
art on any proprietary product -- the manufacturer changes the formula
whenever however and does NOT send you a printed announcement, or so much
as a sympathy card when the new one doesn't work.
Judy
.................................................................
| Judy Seigel, Editor >
| World Journal of Post-Factory Photography > "HOW-TO and WHY"
| info@post-factory.org >
| <http://rmp.opusis.com/postfactory/postfactory.html>
.................................................................
> keep. It goes on and shows you how to mix using glue. I satrted
> working alt -process with gum I have not done it in a long time but I
> never heard of using glue. I know there a lot of you out there who
> work with gum. Have eny of you used glue?? I got my Amexp bill on the
> book it was $ 33.34 in dollers Take care James Romeo,
>
>
>
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