Toning is required to improve image color and enhance image stability. If you
don't, reddish brown prints will result and a strong loss of density will appear
during fixing. Try the most simple formulas first, e.g. those with thiocarbamide
or ammonium thiocyanate (ammoniumrhodanide). One which I used for some time and
gives neutral tones was:
To 25 ml of a 1% gold chloride sol. slowly add a 2% thiocarbamide sol., until
the reddish precipitate that forms first, dissolves again. Fill up to 1 liter
with dest. water. add 0.5 g citric acid and 10 g sodium chloride.
There are hundreds of formulas for acid, neutral and alkaline toners. Alkaline
toners don't keep very well, but work rather effectively. The neutrals keep and
work well. The acids tend to give more brownish tones, but you can never predict
the color before you tried it... I just tested about 20 formulas and got
surprising results. Everything from pink to deep black, some with split tone
effect, but none with the desired bluish or violet hue... If you use acid toner,
rinse the print before placing it in the fixer, or otherwise some sulfur toning
may occur in the fix.
Mask your negs or cut off the black edges of your prints before toning: The
black parts take much gold from the solution. Split tones may look nice, but
show that s. th. is wrong with the toner (exhausted or whatever - you must be a
chemist to understand what's going on...)
Not to forget the combined toning/fixing baths. The problem with them is, that
the toning often works faster than the fixing, so an additional fixing bath is
recommended.
Although simple 10-15% sodium thiosulfate fixer is recommended in the
literature, I found the ordinary rapid type fixers to work well (after toning).
Get some manuals from the turn of the century (ca. 1895-1925), esp. those which
not only list formulas but also cover the chemical background information, if
you want to understand (or become confused ;-))
Klaus Pollmeier