Hello Jaime:
I'd like to verify that you didn't add a zero onto those weights because
the formula is *so* much more concentrated than we use.
We had a very enlightening message from Peter Marshall a week or so ago
pointing out that our customary cyanotype formula (the one in most
modern-day manuals) arose from an error, when someone forgot that you
combine solutions A and B and allowed the full hundred cc of liquid for
each. But still, the "authentic" more concentrated formula would only have
come to (as I recall):
40 grams ferric ammonium citrate in 100 cc water
16 grams potassium ferricyanide in 100 cc water
Now you write 160 and 70 gms respectively in only 100 cc water, which
would come to 320 grams and 32 grams in our total 200 cc water.
In other words, it seems that you're using 8 times the concentration of
feamcit, twice the concentration of potassium ferricyanide. Where did you
get this formula? Any comments anyone?
Judy