Most of the formulas with tannic acid and an alkali work, almost none of
the others do. The tannic acid will work with ammonia, the hydroxides,
and sodium carbonate -- which my students and I use regularly -- and I
assume it will work with borax, etc. as well.
There's almost always a serious loss of density. And unless you keep the
toner baths VERY clean (one shot is best for control) paper base will be
seriously stained. Also, the richest tones seem to come from the thicker
papers that have, presumably, more color in them to start with.
Best bet is to TIME the baths, and tone a 21 step, preferably several,
which will show where the split of tone happens -- and where flattening,
if any occurs.
Timing and dilution of the baths are interchangeable (more or less) just
like time & dilution in developing silver film. In class we adjust
strength of baths to suit as we go along -- in other words, mixing a
formula to fractions of a gram or a cc is, let's say, de trop.
I'll add that a couple of my students took it into their heads to tone
cyanotypes in tea, and gave me samples with tea bags attached, a
different tone, BTW, for each type. This was lots of fun, but required 8
hour soaks, & paper base was seriously stained. (Effects were quite
lovely, however.) Ok, tea has tannic acid -- but you knew that.
In my experience, "purple" tones, however acquired, fade as soon as they
dry. A great disappointment, since they're fabulous at first.
I got a fairly drab purplish blue with gallic acid, however -- and a year
later it was much drabber. That, I think, is an ongoing risk with toning
cyanotypes, and I'd love to hear from someone who knows more about their
I never could get the bright yellow Crawford claims happened with the
sodium carbonate/tannic acid (to the paper base) -- but his formula was
about 4 times too strong.
> 3. Red-brown: Treat for 5 minutes in tannic acid (6gm to 180ml
> water), then sodium carbonate (6gm to 180ml water). Wash.
> This one actually works :-)
> If this last method is the one you have tried that produced a
> "lifeless brown", perhaps a different paper would yield better
> results. I think I used Strathmore drawing paper.
We find that drab often comes from over-toning,or a not dark enough
original (which should look TOO dark) because the toning
process not only costs density, too much of it (especially used baths)
stains the paper base heavily, which also costs contrast.
As it happens, my neighbor, John Dugdale is having a show of toned
cyanotypes at Wessel O'Connor gallery (Tribeca) opening Nov. 17. I saw
his preliminary prints this afternoon & they are very beautiful indeed.
(He does however insist on arty heavy wavy bubbly German hand blown
special order glass over them, which has me tearing my hair out, but he
says collectors adore it. When a work is bought and shipped, he says,
they quiz him to be sure they're getting the antique glass!)