Gum a la Sam Wang

Good Morning List!

I'm beginning to see the light at the end of the tunnel! 3 weeks left and
school will be out.

Well, I've had some sort of gum epiphany thanks to Sam. I have struggled
since mid last year with trying to make digital negatives work for me. I
spent 3 weeks, if you all remember (see that "you all" in there? I'm
getting used to the South!) enlarging 70 negs the old fashioned way in the
darkroom and that works fine but sooo time consuming. My digital negs were
always flat and gross in gum.

So with Sam's article prompting me, since I normally use ammonium dichromate
at saturated dilution (30%), which equals (bear with me) about 0.3 g per ml
of solution, I realized that Sam's 0.3 g. of am di per 5 ml was 1/5 (!) the
strength of mine. To approximate Sam's strength I just used 1 ml of mine
plus 4 ml water (didn't use dry am di because I already have a pint of the
stuff mixed up).

The first attempt was the same thing--a flat image. THEN I realized my
error. I was ASSUMING that such a low dilution would necessitate a longer
exposure--NOT the case. My diginegs are exposing somewhere between 1 and 4
minutes at *most*, underneath an Edwards BL unit--usually 1 or 2..

Now I knew intellectually that less dichromate, more contrast, less
exposure, more contrast, but experientially I had never tried diluting it
that drastically....

With less dichromate, less di stain. Less hell on the environment. I stuck
it in water and it cleared within probably 10 minutes. Perfectly contrasty.

I also (gasp) tried his method of just mixing in a dab of color instead of
using premixed gum/pigment combinations and that worked great; much more
flexible altho you gotta watch the streaking so mix well.

Ed Buffalo, no more black squares!

I know, I know, those of you inveterate gum printers have probably been
doing this all along, but when you come from the "if a little is good, more
is even better" generation, it just seemed like the more dichromate used,
the quicker and better all would be. Kinda like "supersizing" the gum
process.

Digital negs scanned with an Epson 3200 at 1200 dpi. They are 3" by 5 1/2"
negs, so similar to a 4x5 (negs from my Dad's estate, some 75 yr old).
Printed at 360 dpi on cheapy Apollo brand Ink Jet Printer Transparency Film
from Office Max, Epson 2200, black ink only, high speed off, 1440 dpi, with
Sam's curve applied after I have flipped the neg horizontally and inverted
it. They are not color separations, as the originals are BW images, but my
originals are in RGB. The negs themselves look very thin, but with detail
in the shadows. No sizing of paper, Rives BFK, paper preshrunk. My gum is
stuff I premixed from powder I had gotten at Photographer's Formulary,
preserved with sodium benzoate, mixed 1 gum + 2 water. Gum/pigment to am di
1:1. Whew. Hmmm...I think that covers all.

I'm not making this report to the list to earn a better grad from Sam--he's
currently on sabattical, even tho he still teaches us all, and shoots with
us, on the side--ah, what a life; to be able to spend 2 years doing one's
art...)
Chris
Received on Sat Nov 22 08:34:08 2003