VanDykes & Gold-Thiourea Toner / my experiment - comments please?

I mixed my own Gold-Thiourea Toner using the formula in Wynn White's
article @ unblinkingeye.com
(http://unblinkingeye.com/Articles/Vandyke/vandyke.html):

Gold Chloride (1% solution) - 12.5 ml
Thiourea (1% solution) - 12.5 ml
Tartaric Acid - 0.12 gm
Distilled Water to make - 250.0 ml
Sodium Chloride - 5.0 gm

I tried to tone a double coated Van Dyke print. I did this after initial
wash of 2mins in %1 Citric Acid + 2mins in plain tap water but before
fixing. The temperature of the toner solution was quite cold (didn't
measure but I guess it was around 14 - 15C). Toner amount was 300ml,
coated size was 23x18cm (7x9"). The print toned in 1min. (but I
continued to tone for an additional 1min - total 2mins) it changed hue
to gray/black (with good Dmax - which is great!) almost competely except
some heavily exposed parts that remained brownish (why? not that I
didn't like it). Some ot the gray/black color converted to brown in
fixer (not much but it was obvious - why?). Then, I tried to make a
second print, same size, same toner solution without replenisment(it
waited the second print in the tray, lights were on - would this harm
the toner solution?). The print toned to gray/black in a much slower
pace, around 3mins. and some very slight trace of brown (or lets say a
warmer hue) was present in very deep shadows. And when I placed the
second print in the fixer it removed the gray/black hue except in the %0
- %10 range and the print color converted to a pinkish - brown (very
different from the first print toned in the same solution). Now, my
questions are:

1. In article of W. White, it's mentioned that Gold-Thiourea tones
highlights and shadows at the same rate. My experience was the reverse,
my toner toned the highlights first, then midtones and shadows
progressively. My tartaric acid measurement was not exact around 0.1 and
0.2gr...(I use a digital gram scale with 1/10 gr. sensivity) Could that
be the problem?

2. What may caused the toner to change so dramatically between two small
prints? Why the color provided by the toner wasn't consistent?

3. Why fixer changes cool gray/black tone to the warm/brown tone?

(I also would like to hear other thoughs & suggestions about this
experiment, my working method and anything else comes to mind about it -
please note that this is my first toning attempt)

(Will post links to the scanned images as soon as I scan them)

Thanks in advance,
Loris.
Received on Tue Jan 13 03:26:59 2004