Printed out silver images show a grain ca. 10x smaller than developed out silver
images. Due to the bigger surface they are more easily attacked by oxidants and
the print must be processed carefully and the image must be protected by gold,
sulfur or platinum toning. Alkaline gold toners produce a more bluish tone
(bigger grains) and are more effective, but the bath is unstable (lasting for a
few hours or so) and therefore much more expensive than neutral or acid gold
toners, which can be stored and used much longer. But they do not tone so
effectively or need more time... An additional platinum toning will give a
neutral, deep black tone and (almost) abolute permanence. Sometimes you find
these prints in albums and can see a brownish 'transferred' image on the
opposite side. This image is caused by the platinum's catalytic power to speed
up paper deterioration, but the photographic image remains unaffected.
There are old aristotype (silvergelatin) prints from the turn of the century
that have survived as if they were made yesterday (usually those with a more
bluish or even violet tone). I found one hidden for decades under the roof of an
old farm's cowshed. When I rubbed of the dirt from the frame's glass, I found a
beautiful wedding portrait from 1905 in bluish-black tone with no signs of
deterioration. (A beautiful moment I like to remember...) Another one I saw just
yesterday in the 'Photographische Correspondenz" from 1887: it had suffered
severe fading.
As there are hundreds of gold toning formulae, it is difficult to recommend a
special one. Chicago Albumen Works give the following in their instruction
manual for CENTENNIAL DW P.O.P.:
Stock Solution A:
Ammonium Thiocyanate 10 grams
Dist. Water 500 ml
(Allow this solution to stand over night.)
Stock Solution B:
Gold Chloride 1 gram
Dist. Water 500 ml
(If starting with gold chloride in a 1% solution, dilute 100 ml of 1% solution
with 400 ml dist. water to make 500 ml Stock B.) Both solutions will keep
indefinitely. 500 ml of Stock A and B will make enough working toner solution to
tone approx. fifty 8x10 prints in four printing sessions, assuming one liter
batches of working toner.
For use, mix in these proportions:
Tap water (70F) 900 ml
Stock Sol. A 50 ml
Stock Sol. B 50 ml
In their leaflet, CAW explains how to use and how to replenish the toner, but
this may be to much here and now. For best permanence, I would recommend to tone
until at least a slight bluish tone has been reached.
Klaus Pollmeier