U of S | Mailing List Archive | alt-photo-process-l | Re: pyro and cyano

Re: pyro and cyano

Chris, when you say "six stops"
--- how many steps on the 21-step is that ?

Hi Judy,
6 stops is 12 steps on a 21 step tablet (1 step=1/2 stop) or 18 steps on a 31 step tablet (3 steps= 1 stop). This is why I don't talk steps because it is confusing with whether one is using a 21 or a 31 or a 44, but a stop is a stop is a stop.

Yes, cyano gets darker as it oxidizes. I never use, and never recommend, hydrogen peroxide because eventually the print will turn that nice darker blue anyway.

(If I display ignorance,
please excuse.... But I live in a 21-step dimension, not a "stop" dimension. In fact when I strayed into the wet darkroom last month on a different mission, I couldn't even make the safelight go on !)

In any event, my rule of thumb for an average neg in simple cyano was 8 or 9 steps, tho I found many ways to modify that. For instance, pages 34 thru 37 of Post-Factory #5 ("Managing the Blues") show differences from light source (sun vs. UV bulbs), paper (Strathmore Artists v. Whatman Fine Print, among others) proportions of parts A & B (as discussed on this list by... Sandy?, Bob Shramm?, others ?) a while back; time on the paper before exposure, delayed development, double coating (according to paper), acid "prebath" ("tends to extend and deepen range very dramatically"), etc. etc. etc.

That issue is dated "August 2000", so (BELIEVE ME !!!) I've forgotten the details (the above is from a quick skim... but I'm not printing cyanotype these days, and need that disk space ...ie, what's left in the brain ... for current endeavors, so am TRYING to stay away from this topic... Tho,
since you insist.... my eye lights on mention that, to my surprise, I discovered that "dry down" in cyano, goes on, not just for one day, but several ... But you knew that ?

There are also 21-steps A through D2 of various ranges & why (p.37). But as in "devil get thee behind me," I change the subject: Another P-F (from around then) shows a "Cyanodyke" -- what the photographer called her vandyke brown prints over cyanotype. The print was very pretty, with nice combined tones (tho in repro b&w only). As I recall, she didn't mention bleaching, tho of course in the other way around -- cyano over vandyke brown -- the silver gets bleached by the potassium ferricyanide in the cyanotype. A short item, but if I locate it, I'll cite.


not suitable for cyanotype as it is for other processes that have longer tonal ranges, unless one were to contract the tonal range of the pyro neg to match cyano--or have subject matter that is tonally contracted anyway.

BUT, and this is my question: does anyone know the maximum DR possible in a pyro neg? I do not have a UV densitometer. And, from memory (which obviously doesn't serve me too well so please answer this, too) a film negative can actually record up to 13 stops of info, pt/pd about 10, BW paper about 7, and cyano about 6...you get my point perhaps.



OHHH man do I need to get back to work, this is too fun posting all these silly visuals, and hopefully someone will benefit except me :)

Christina Z. Anderson