> Judy,
>
> My cyanotype formula (liquid) does keep well but I keep it in two
> parts in two bottles and mix it just before use.
Keeps "well" compared to what?
I, too, keep the two parts in two bottles (tho I tried them in one bottle
just for a test). I did, however test the two formulas against each other;
the one with the oxalic acid began to veil the highlights within a month.
If you weren't printing 21-steps you might not notice that. My "regular"
cyanotype formula didn't veil for 3 or 4 times that period -- or until it
was used up.
> 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.
That's funny -- when I began teaching VDB I panicked & read everything I
could find in print on the topic. I can't remember anything about it
not keeping. What comes to mind is phrases like "keeps well," or "keeps
for months." So a year is 12 months -- and it did keep well...
> 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. ;-)
Actually Bob, I should check the formula, since I'm not certain it was
*exactly* what you posted. I simply recall that it substituted oxalic for
the tartaric acid, as yours did.
In any event, I tried it on at least 10 papers, only one or two of them
with an added size. A couple were OK, but on most the emulsion either
washed away or was very fragile. But do not malign our terrific New York
water. Among other possible explanations is that your "oxalic acid" was
really dead...
Cheers,
Judy