Re: brush vs tray size for gum
Kerik,
About the humidity:
I live in a very humid climate and have no problems printing gum in
high humidity, but a few weeks ago I found that when the humidity
plunged to an almost unheard of 17%, exposing even at 3X my normal
exposure time wasn't nearly enough exposure; the gum just ran off the
paper in development. According to a graph I found in some
information from a printing industry group, that much of a drop in
humidity should necessitate 8x the exposure to harden dichromated gum
arabic to the same degree. But before I tried increasing the
exposure by that much, the wind changed and the humidity went back to
93%, and suddenly everything went back to normal.
So my first thought was that your development was slow and difficult
because with the high humidity, you were using exposure times that
were too long for the conditions, and consequently overexposed the gum.
But this explanation stops making sense (there's those pesky data,
interfering with perfectly good theories again) when it comes to your
observation that unsized paper printed fine and developed well in a
reasonable time.
But your observation that with the unsized paper the development time
is closer to the normal development, implying that it's still greater
than normal, indicates to me even with the unsized paper you're
getting some effect of the humidity on speed of the gum, so I think
that may still be probably somewhat of a factor.
But I also wonder whether due to the increased humidity, the sizing
might not have been completely dry before printing; obviously if
unsized paper works better than sized paper, there's probably
something about the sizing that's contributing to the problem, as you
surmise.
Chris,
About whether sizing needs to be "aged" before printing:
I've never found this to be true, as I'm always sizing paper on the
fly and printing as soon as the sizing is dry, and I keep wondering
if it's just another one of those myths that keep popping up or if
there's something to it. But one thing I have seen, is that if the
sizing isn't completely dry when printed (and in my humid climate
even brush-sized paper does have to be dried for several hours, if
not overnight) then I've sometimes seen bright yellow dichromate
stains in the paper, and also pigment staining. So while my own
experience doesn't support the idea that sizing has to be aged per
se, it does suggest that it's important to be sure that the sizing is
dry before printing.
As to brush vs tub, I think it's probably a matter of personal
preference. I prefer brush-sizing because there's less glyoxal-laced
gelatin to dispose of afterward, and I find that as long as I keep
the paper warm and the gelatin warm, it brushes out easily enough to
get a good even coat.
Katharine
On Sep 26, 2006, at 8:49 AM, kerik@kerik.com wrote:
Chris,
I agree that tray sizing is a lot of mess and hassle for no
substantial
benefit. Plus, why do the sizing in 2 steps when it can be done in
one? I
use either a glass rod (puddle pusher) and/or a brush. I add the
hardener
(formaldehyde in my case) to the sizing just before sizing each print.
Three drops of formaldehyde and 5 ml of 3% sizing easily does an
8x10 to
11x14 print. In these tiny amounts, exposure to formaldehyde (or
whatever
hardener one uses) is minimal. I get very even sizing this way. A
little
bit of curl to the paper, but nothing that causes any problems.
I tried B.M. glut and did not like the results. It resulted in slower
development and considerably more staining than with formaldehyde.
As for sizing with unhardened gelatin, that sounds like another in
a long
line of T King's erroneous hyperboles.
Speaking of gum, I taught a gumover workshop in Philladelphia this
past
weekend for www.projectbasho.org. On sunday it was 80 degrees F and
82%
humidity in the darkroom. That's the first time I've printed gum in
sauna-like conditions and it created some hassles with very slow
development and the need to intervene with some brute force measures
(brushes, fingernails, sandpaper). Anybody have similar problems
printing
gum in high humidity? The conditions seemed to cause problems with
the
sizing in particular because development was much closer to normal
when I
did a single coat of gum on unsized paper right out of the plastic
bag. I'm
speculating that the humidity either prevented the gelatin from
hardening
completely or it allowed the gum solution to soak into the sizing a
bit
rather than sitting on top. Despite the problems, I believe a good
time was
had by all. Although I always want things to go smoothly during the
workshops, it's good for the students to learn how to deal with
problems
when they come up.
Kerik
www.kerik.com
Original Message:
-----------------
From: Christina Z. Anderson zphoto@montana.net
Date: Tue, 26 Sep 2006 08:08:22 -0600
To: alt-photo-process-L@usask.ca
Subject: brush vs tray size for gum
Hi All,
This weekend was time for sizing paper, and since I was doing small
sizes
(11x14's) I decided to tray size instead of brush size to see if it
had any
added benefits to brush sizing.
I was sizing with gelatin glutaraldehyde as usual. I did use a
piece of it
right away, same day, and had no problem with the sizing not being
hardened
and producing "magenta squares" as did Carmen. However, I was
using glut
that I bought from a medical supply house (now available at the
Photographer's Formulary) and not Black Magic. The gelatin on my
paper was
not slimy in any way so I know it was hardened. I am still not sure
why
Carmen got that problem, and am wondering about the suitability of
Black
Magic, therefore, with its added sulfite. It sounds like the same
result I
had when I tried Terry King's advice to use unhardened gelatin and got
black
squares.
With tray sizing and cautions with glut, I gelatin sized the paper
first,
and then the next day I soaked the sized paper OUTSIDE in a tray of
50ml
glut to a gallon of water. That worked well, but I would only tray
size if
the hardening part could be done outside to minimize fumes produced
by the
surface area of a whole tray of hardener, whatever type--glut, gly,
formaldehyde. (When I brush size I keep the solution capped inside a
thermos
and pour out a cup at once.) The gelatin paper went in "slimy"
feeling, and
went out unslimy.
The paper works fine but I learned a couple things: paper tray
sized with
gelatin will sink to the bottom, not float as does brush sized paper
(except
Arches) so if I am going to leave the paper soaking for a while it
needs to
be face up. I learned that the hard way. Back to floaters and
sinkers, Mark.
The paper does curl less than brush sized, but it doesn't seem
worth the
added trouble of trays. This is the only benefit I can see. Oh,
maybe more
evenness of sizing? I don't know this one yet...will have to print
all
papers.
My husband set up an ingenious "clothesline" for me--a rung ladder
on its
side has plenty of hanger-ready rungs.
I learned another thing the hard way: I printed 4 prints on the
unsized
but
shrunk paper with a cyanotype layer, put the paper through the hot
gelatin
sizing process and didn't THINK that the 140-whatever degree
gelatin would
shrink the paper even more and make registration a B---H but you
bet it
did--warped and shrunk. Luckily only 4 prints ruined. DUH. Or, as Clay
says,
DOH.
The bottom line is that brush sizing is sooo much easier and works
well and
uses way less gelatin--I sized 24 11x14s with a a liter of 3%, and
normally
I can do that many 16x20s with the same. I don't think even with small
sizes
I would tray size...
That's all my truly exciting weekend experience!
Chris
CZAphotography.com
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