Re: Gum prints with an enlarger
M Rand Carlton (mrand@snowcrest.net)
Thu, 11 Jan 1996 09:57:41 -0800
I would like to take this opportunity to describe an gum enlarging
experiment that I conducted about a year ago.
1. I dismanteled an old transparancy overhead projector, for use as a
housing for the light source.
2. Inside I mounted a 300 watt murcury vapor lamp and power supply, from a
yard light, the kind you find at Sears.
3. I then mounted (taped) an 8x10 laser printed monochrome negative onto the
glass of the overhead projector. By now the projector is setting on its
side, as it was easier to align everything horizontally.
4. For the lens, I used my old Seroco 5x7 camera (12 to 14 inch Goerz lens)
with the back removed. Camera was oriented backwards with lens facing the
print surface.
5. I draped black cloth over everything, more or less cutting down on
lateral light leakage... it still leaked plenty. This contraption was set up
in a darkroom. I then focused the image.
6. I placed a coated piece of Rives BFK (gum arabic w/sodium dichromate)
about 4-5 feet in front of the camera lens. And exposed for 5-6 minutes.
The results were a charming enlarged image of my daughters face, It cleared
well, however we need to keep in mind this was not a continuous tone neg. I
only exposed it once, as that gave me enough information to know that I
wanted to make a better enlarger.
I of course have since gotten sidetracked, however, this excersise has
convinced me that reasonable results can be achived.
Hope this helps
Rand
M Rand Carlton
mrand@snowcrest.net
Photography...
"The process is
the product"