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

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

From: "Ryuji Suzuki" <rs@silvergrain.org>

> 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
> performance.

www.thorlabs.com or www.edmundoptics.com certainly have filters for your
You might look for a BANDPASS (interference) filter.
> 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 believe those (non-white) high-power LEDs don't emit any significant NIR
Take a look at the spectrograms of a LUXEON (http://luxeon.com/).
By the way their amber types (~590nm) are pretty monochromatic (bandwidth
around 30nm or so).

May I ask what particular sensitizing dye you use?

> 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.

www.acriche.com/en/product/prd/acriche.asp sells high-power LEDs that run at
AC 100-230V directly.

 > 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?)

You may try these:

An alternative would be using threaded rods. As of now I've been unable to
locate them, but there certainly exist PA-6, PTFE and other plastic threaded
rods which could be easily cleaned.