U of S | Mailing List Archive | alt-photo-process-l | Seeking: (1) orange LED safelight, (2) wire coating rod

Seeking: (1) orange LED safelight, (2) wire coating rod

  • To: alt-photo-process-l@usask.ca
  • Subject: Seeking: (1) orange LED safelight, (2) wire coating rod
  • From: Ryuji Suzuki <rs@silvergrain.org>
  • Date: Tue, 08 Apr 2008 07:26:29 -0400 (EDT)
  • Comments: "alt-photo-process mailing list"
  • Delivered-to: alt-photo-process-l-archive@www.usask.ca
  • List-id: alt-photo-process mailing list <alt-photo-process-l@sask.usask.ca>
  • Reply-to: alt-photo-process-l@usask.ca

Hi all,

Boston is getting some infrared from the sky and I'm thinking
about making infrared plates this year. I have several types
of plate emulsions (daylight ISO equivalents up to 1000) and
an infrared dye. Now, the matter is coating the emulsion on
glass, and then processing.

After a while of thinking, I came to a conclusion that an LED
safelight made from ORANGE LEDs is best for this purpose.

A standard OC filtered safelight contains too much infrared
and they instantly fog the emulsion. Not useful.

A standard safelight for infrared material is dim green light,
but uses Wratten 7B or similar green filter with spectral
transmission peak at around 510 nm for best night vision
(rod sensitivity) and good infrared blocking

However, for my particular dye (spectral absorption of about
700 to 850 microns on silver halide emulsions), it is probably
best to use 600-650 nm range for safelight. This is because,
with a fast emulsion, 510nm light can fog the emulsion (AgBrI
emulsion can be sensitive to about 540nm). Red LEDs contain
spectrum beyond 700nm and this will fog the emulsion. So, I'm
thinking that orange LEDs would allow me to coat the emulsion
in quite high level of illumination.

I have no problem in buying bulk LED components and soldering
them myself, but I wonder if such an orange LED safelight
exists as a commercial product to save my time.

Now, I've been using a glass rod wound with silver wire, but
this is such a quick kludge and I'm looking for something
better. Does anyone know where I can buy a glass coating rod
with a handle pre-wound with 316 stainless steel wire? (Or,
teflon coated stainless wire?)

Ryuji Suzuki
"The truth that I am seeking is in your missing file."
(Bob Dylan, Something's Burning Baby, 1985)