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>

> I wanted to avoid that range, partly because 590nm may fog
> high speed emulsions using a green sensitive dye. My OC
> safelight certainly fogs emulsions using any of my ortho dyes.
> I think something like 625nm with fairly narrow spectral
> emission would be ideal because it can be used for two projects.

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.

> > 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.
> Good idea! A threaded rod made from some hard polyamide or
> fluoropolymer of low friction and good surface action
> (wettability) would be ideal.
> But do you think they are straight enough to coat glass plates?

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 am not sure about their wettability though. Fluoropoylmers most likely
might be more difficult in that respect.
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. In
that case I didn't notice any problems when applying gelatin or hydrophilic
polymers on glass or plastic substrates. But I don't know to what extent
those rods are "inert" with respect to a silver halide emulsion.


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