I have read, but not confirmed, that the "B" solution in Berg Rapid RC
sepia toner is thiocarbimide. If so, somewhat ironic since it is billed as
a safer toner and as noted elsewhere thiorcarbimide is a suspected
carcinogen. I have toned Agfa multigrade classic, first in gold 231
followed by the B solution only of the Berg. It makes a nice split, with
the darker areas going sepia and the lighter areas not. Not too flashy,
with the right subject.
Regards,
--Ken Carney