>Bob Schramm
Risa, Bob,
I believe that 350 means the wave length in nanometers at which the tube
emits the greater percentage of its light.
A few quick notes on light sources for alternative processes.
1) It is almost as economical to make a unit with 48" tubes. The 24" tubes
are something of an odd-ball size and in many instances actually cost more
than the 48" ones.
2) Electronic ballast is better than magnetic ballast for giving repeteable
results in exposure. Of course, for really precise work you need a light
integrator.
3) With some of the alternative processes (gum, carbon, and perhaps
platinum) many on this list have found that the GE Daylight tubes, which
emit most of their light in the 440 nanometer range (or close thereto) are
as effective as UV lights at 350 nanometers. In my own work in carbon I
find the daylight tubes decidely superior. A lot of experimentation by me
and others using different light sources was done earlier this year. See
the archive for some of our results. As I recall, the daylight tubes did
*not* give good results with cyanotype.
4) It is advisable to space the tubes as close together as possible. Leave
just enough room to place and remove the tubes. This will allow you to
place the negative/sensitized material at a very short distance from the
light source. None of the self-contained ballast/holder units that I have
seen allow for spacing this tight, so you should consider wiring the whole
thing with the little bi-pedal tube holders. It is more work, but you can
space the tubes very tightly with this system.
Sandy King