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: martinm <martinm@gawab.com>
Subject: Re: Seeking: (1) orange LED safelight, (2) wire coating rod
Date: Thu, 10 Apr 2008 11:21:21 +0200

> In which case you'd have to cut the weak green line present
> in all the red LEDs I've seen.
> You can easily check that out with a diffraction grating, a
> CD or a DVD.

Do you know if orange LEDs of 625nm peak have that line?

Well, maybe I'll check whether orange LEDs can fog a high
speed negative emulsion without dye sensitization.

> That will largely depend on their length and diameter. By
> the way, DELRIN might be another candidate (I meanwhile saw
> that you can get a large selection of threaded plastic rods
> in the US, thanks).

I'll look into them...

> I am not sure about their wettability though. Fluoropoylmers
> most likely might be more difficult in that respect.

That may vary. But that may be ok with a combination of good
surfactants. Since coating rod wouldn't make bubbles, I could
use some effective anionic surfactant and blend in a small
amount of a fluorosurfactant, or a branched secondary alcohol
ethoxylates, at least. (I usually use non-branched ones
whenever their performance is adequate, as they are

> On the other hand I've used some liquid mold release
> products made of fluoropolymers (similar to Teflon) to treat
> a simple metal threaded rod.

Is that a coating tool? Can you elaborate?

> But I don't know to what extent those rods are "inert" with
> respect to a silver halide emulsion.

If the coating is PTFE or something, that's good.
HDPE, PVC, ABS, etc., are also good.
What I'd worry is iron, zinc, copper, etc.

Ryuji Suzuki
"People seldom do what they believe in.  They do what is convenient,
then repent." (Bob Dylan, Brownsville Girl, 1986)