"The prints are first bleached in a solution of ferricyanide and bromide,
or copper cloride. The bleaching formula for sulfide toning is suitable.
The prints are then washed thoroughly and placed in a solution of sodium
stannite prepared as follows:
Stannous chloride.......10 g
water to ...............100 cc
"To this add with constant shaking 70cc of a 10% solution of caustic
sodium [sodium hydroxide] until the precipitate first formed is
redissolved. Finally add
water...................80cc.
"This results in a purplish black color on bromide prints and a
sepia-brown with chloride developing papers. Warmer colors may be
obtained by using potassium stannite, which is prepared in a similar
manner using, however, 100cc of a 10% solution of potassium hydroxide and
50cc of water to each 100 cc of 10% solution of stannous chloride."
Got that?
Note that I did find several references to a proprietary, ready-mixed tin
toner marketed by Burroughs, Wellcome. Someone really interested could
probably look up the formula, assuming it was patented. This does tend to
contradict Neblette's assertion of mainly theoretical interest...... My
sense of the situation, however, is that some of the MYRIAD
selenium/sulfide/thiourea formulas lying around in MANY formularies & old
books would be easier to get the chemicals for & perhaps work better with
modern papers -- if you want brown. Plus how archival is tin? Is this known?
Judy