I had a chance to meet Tod Gangler yesterday at Alt-Photo Pacifica, and pick his brain a bit. I found him to be quite generous with his time and knowledge.
I learned a few things from him that I'll be writing up the next couple of days. Coincidentally, on the Yahoo carbon list, Sandy King had asked about how light sensitive this process was with regards to handling both the raw sensitizer and the finished tissues. Since I have that written up already, I thought I'd share that first.
Apologies if you've already seen this on the Yahoo list.
The sensitizer is most sensitive as a dry powder, decreases as its put into
solution and added to the emulsion, and is even less sensitive in the dried
Tod's recommendations for maximum light levels were thus:
-- Red safelight only for weighing the powder and adding it to solution.
-- Safelight + very dim 60W tungsten (as low a setting on a dimmer as
possible to get it to light) for adding to the emulsion.
-- A 60W bulb mid-way on a dimmer for pouring the emulsion. He uses a slightly
lower level for black and yellow, since his pigments are more prone stain, so
minimizing fog is first-priority. Slightly higher levels for cyan and magenta
because they are less prone to stain. This may vary depending on the exact
pigments that one might use.
I'll add this from my own experience: Pouring tissues onto clear substrate in red safelight conditions is frustrating if you're not using some sort of frame. Pouring onto a yupo-type material, as Tod does, might be easier because it's easier to see the edges of the substrate. I've taken to outlining the tissues (which are squeegeed onto glass) with a silver sharpie. Much easier to see the edges that way. I may consider switching to a Yupo-type material, much as I like using the Dura-Lar.