Cyanotype can be toned with lead acetate which converts the prussian
blue to a deep cobalt blue. Formula in the archives and "Keepers of
Light." The tannic acid and sodium carbonate toners will work as well
and can be used to produce beautiful brown-tan and purple tones. I have used
this quite successfully. Again, the formulas are in the archives.
If you find out how to tone VDB, please let me know. I asked this question
on the list a while back and nobody answered. Judy did post some formulas
for Kallitype toners which I plan to try on VDB but havn't yet. They, also,
should be in the archives.
Bob Schramm