The DARKROOM COOKBOOK, Third Edition

Photographic Reduction and Intensifi cation 131
5 minutes, with agitation. After toning, soak the prints in a second bath of HCA (without the
selenium), then wash for the recommended time.
Dilution ratios can vary from 1:9 to 1:39, depending on the toner and paper combination.
To determine the correct dilution make fi ve identical prints. One should be left untoned. The
others should be toned for 5 minutes in different dilutions of selenium toner, 1:9, 1:19, 1:29,
and 1:39. After washing check the four toned prints against the untoned print to determine
the lowest dilution that can be used without a color shift.
Some workers recommend mixing the stock selenium toner with a working solution of
Hypo Clearing Agent. Others, such as Bruce Barnbaum, suggest that this will shorten the life
of the toner. Bruce reasons that the useful life of HCA is approximately eighty 8 � 10� prints
or equivalent fi lms, and that the useful life of selenium toner is at least two hundred 8 � 10�
prints or equivalent. When the HCA is exhausted the bath needs to be replaced, which is a
waste of selenium toner and results in more selenium being introduced into the environment.