Re: Blue-Black Cyanotype & Luster

On Tue, 4 Oct 2005, Kai Hamann wrote:

> The cyanotypes tannic acid toned that way have to be dried without
> having contact to any alkali. E.g. if they lie on a buffered paper the
> cool tone gets warmer where the wet print is in contact with that paper.
> That´s basically the principle how the other lines of test prints were
> made -- the finished cool toned prints were put in a weak alkaline
> solution (like 0,5 % sodium carbonate) often only for some seconds. The
> blue regained by the acetic acid bath disapears and the tannic acids
> brown is enhanced. Then the excessive alkali is removed by a good wash
> in neutral ph tap water. This kind of color adjustment works only with
> the tannic acid toned cyanotypes. With gallic acid toned prints there is
> virtually only a substantial image loss and staining.

Those were exactly our findings too -- as I probably put in that cyanotype
issue of P-F, I tried every cyano toning formula old & new in the books --
That is, all but the one on the back cover of P-F #9, "Toning Blue Prints
Black" from "The Camera," Jan, 1917... I *asked* folks to try it but
haven't heard from anyone who did (maybe the type was too small?)... So:

Completely bleach blue print in 2 grams silver nitrate dissolved in 1
liter water, which takes about 25 min. Wash print until all soluble
silver-salt is removed, then redevelop in an oxalate of iron developer.
(that's probably why I didn't try it, didn't have the developer.) "The
print comes out black and resembles a platinum print." (!!!)

OK???

Otherwise I found the only controllable attractive toning for cyano to be
tannic acid with an alkali, as Kai describes. The color & depth of tone
is related to the length, order, and strengths of the two baths, how long
& how well washed between, etc. etc. My students loved that toning, so we
did it a LOT, and some of them tweaked it to perfection. With right combo
of variables truly gorgeous split tone, rich dark purple in shadows,
reddish or tan highlights.

I too found the gallic acid was a bust... as Kai points out.

It's my hunch that these non-working formulas got into the old books
because (a) they were copied from other books without testing and (b)
somewhere at some point with some combination of ingredients somebody
found or thought some of them worked...

J.
Received on Tue Oct 4 21:24:23 2005