My cyanotype formula (liquid) does keep well but I keep it in two
parts in two bottles and mix it just before use.
As to VDB I confess that my concerns about keeping the mixed
sensitizer came from what I had read in various sources, but I had
never tried it. Thats why I love this list. I learn stuff all the time.
I don't know why your VDB images are washing off the paper when you
use the formula I posted. I have never had that problem. I have been
using unsized platinium printing papers. Did you size the paper you
used first? Maybe its the NY water. ;-)
Bob