Re: Gum woes

Scott,

When I mix an emulsion (either using tubes or powders) a large part of
it is by feel acquired through experience. I vary the amount of
pigmented gum in the mix and generally use between a 2:1 and 1:1 gum +
pigment to saturated dichromate solution ratio, depending on what I'm
trying to achieve with the coat.

For me, the viscosity is correct when I can coat an 8x10 or 11x14 area
in one direction and then even it out at 90 degrees immediately. If the
mix (and humidity) is right, the emulsion starts to set once this is
accomplished. I follow this with a smoothing with a dry fan brush first
in one direction and then the other, again immediately. The emulsion
has set in this time which is probably on the order of 45 seconds total.
 I then dry it in the dark for several minutes using a hair dryer
without heat. I've never let the emulsion just sit there on the paper
for a minute before smoothing. Perhaps this is contributing to your
problem.

Joe

>>> swphoto@verizon.net 05/08/05 9:41 PM >>>
Hi Kate,

I hadn't thought about having too much emulsion. To me the second and
third
coats seemed thin but then again i'm just a beginner with gum - most of
my
work is with silver gelatin, cyanotype, kallitype, van dyke, salt, and
albumen. Basically I use a 1-1/2" hake to spread enough emulsion to
cover an
area a little bigger than the image without puddling, let it sit a
minute,
then use a dry 4" hake to smooth out the coat. I have a couple of foam
rollers here somewhere I can dig out, so i'll have to try your
suggestion
this week.

Regards, Scott

swphoto@verizon.net

----- Original Message -----
From: "Kate M" <kateb@paradise.net.nz>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Sunday, May 08, 2005 7:06 PM
Subject: RE: Gum woes

> Hi Scott, I'm also wondering if too much emulsion might be a problem
for
> you. I brush the emulsion on, then roll over it in several directions
> with a cheap foam roller (you have to roll any excess off the roller
> onto paper towels or similar). This makes the emulsion layer very very
> thin ( important for gum).It also eliminates fisheyes. I find that if
I
> have too thick an emulsion, I have problems with graininess as some of
> the gum doesn't get exposed throught to the paper base and therefore
> falls off during development.
> Kate
Received on Sun May 8 20:35:10 2005