Until well into the 20th century all cyanotypes were made with brown
scales as the green scales were unknown. The early formulas didn't say
"brown scales" because they didn't know there was any other kind. And our
chem prof at school teaches his photo chemistry class with brown scales
for cyanotype to this very day, as I discovered when he tried to give me
brown back one day after borrowing all my green.
In fact it has occurred to me that the brown scales may have a different
chemistry, which might account for the *many* early toning formulas that
simply do not work today. I mean the supposed lavenders, greens, etc. I
just tried a new one at school that doesn't work, either, BTW -- bleach
the cyano back in 2% sodium carbonate, tone in 10% copper sulfate,
*supposedly* to black. We sacrificed a print to the cyanotype gods, left
it a wan tannish blue.
When green scales became available (as explained in photo magazines of the
1910 to 1920 period) they were at first extremely costly, so photographers
continued with the brown a while longer. But Jack is right, the green is
described as "five times faster" I think it was.
Of course this is all well and good, but what about my lot #3???
Cheers,
Judy