Gum Bichromate sources
Norman Strand~
negatives the same size as the print, either use a large camera or enlarge
small negatives. see Millard, Howard. _Enlarge your negs--Why?_ Modern Photo-
graphy, may 1980 pg 102.
contact printing frame: I now use a 16x20x1/2 inch peice of plate glass.
it is very heavy, but works better than anything else I have used.
The commercial contact printing frames that I have do not press the
paper flat enough.
potassium dichromate: photographer's formulary 1-800-922-5255. The bottle
of potassium dicromate that I have has a kodak lable on it but I do not
know if kodak still sells it.
watercolor paint: Try a local art supply place. Windsor and Newton,
grumbacher, liquitex are some brand names. The colors are not really
the same. If you say buy a tube of some color of grumbacher watercolor
and then go back later and get another tube of the same color, then those
two tubes of paint will be alot alike. If you buy a tube of some color
by windor and newton, and then go and buy a tube of paint by some other
manufacturer, then the color and consistancy of the two tubes will not
match. It is easier to work with pigment colors rather than staining
colors. Some of the staining colors are thalo blue, thalo violet, all
cadmiums, cerulean blue I am not sure of the complete list of staining
colors. If you are not sure put some on a peice of paper, let it dry
and then try to wash it off. If it comes off, then it is OK for gum
printing. Some colors I have used successfully are, charcoal grey,
lamp black, ultra-marine blue, cobalt blue, and emerald green.
gum arabic: Try the art supply place. Some watercolorists use it instead
of water to get richer colors and to do different style blending.
Paper: There are none that will work without some changes. I have been
using aches hot pressed watercolor paper that has alot of gelatine
sizing added, and hardened in formalin solution. formalin causes cancer.
A better preparation would be to coat the paper with spray starch and
iron it. Some people coat their paper with gesso mixed 1:1 with water.
(gesso is a paint used to seal artist canvases before the painting
is started). Watercolor papers seem to be the standard. If you
want to try some other paper, then soak a sample in water for a
half hour and see it you can lift it out of the water without tearing
it. Some papers turn to mush in water.
A note: potassium dichromate is a poison, contact dermatitis is very
common amoung people who use it. It can cause ulcers if left in
contact with the skin, it would be better not to get it in the lungs.
A dust mask, rubber gloves, mixing out of doors or in a fume hood,
and caution are good.
David Scopick has a new edition of _The Gum Bichromate Book_ out. I have
not seen the second edition but the first edition was very good.
Nettles, Bea. _Process: Kwik Print_ Modern Photography november 1983 pg
110. Article on kwik print a modern modification of gum bichromate
that works well.
An other note: There is no pottasium dichromate left in the print
after it is processed.
Norman Strand