> As for the final "darkness" of the print, I have watched several of my
> prints darken *considerably* over a period of months -- as much as 20
> percent beyond the hair-dryed-and-let-age-for-a-couple-weeks stage.
That is indeed curious, something I have never noticed. How did you
determine this? By eye, or by test? If by test, I wonder how you
framed it?
Are you talking about "darkening" at every step, rather than
fogging of highlights? If it's across the board, it may not be that
crucial to quantify.
> I find estimating the final density of the print to be quite difficult.
> I thought at first that I was simply not washing them long enough, but
> "Keepers of Light" says that will cause the image to fade, not darken.
Assuming your procedure, mix and *paper* are constant, the only variables
(that I'm aware of, I hasten to add) in final density are the RH and the
age of the emulsion. Therefore a test made today would be a permanent
guide to ultimate density when it's aged however long it takes.
On a day here when the steam heat is in overdrive for very cold weather, a
cyanotype soaks up more emulsion, prints darker. HOWEVER, double coating
has approximately the same effect. So you make a 21-step, which not only
gives a check on your tonal separation, you use it as a pin-up. After a
few months it's a permanent guide to ultimate density.
As for the age of the emulsion, my tests have I confess been inconclusive
(I have no weakening at home, my students using same chemicals at school
do.)
If you're saying that you lose shadow separation over time -- ie that
*relative* density shrinks in the low register, you may be over-exposing.
(Another reason to live by the 21-step.)
Judy
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