> > I have heard (& read) that if a Cyanotype fades you can place it in the
> > dark for awhile and it will regain its color. Is this true? Or only
> slightly
> > true (more recent prints will come back, but old ones will not)?
> >
> There may be some truth in this. When I got the samples back from testing
> they had been in the dark sometime I imagine, certainly away from intense
> light, probably in a drawer for several weeks or months before being posted
> back to me.
>
> This might account for the difference between my visual estimation of the
> samples and the comments of the actual tester.
I made a test a few years ago of leaving a cyanotype half in and half out
of a book on a south-facing window sill for several months, at the end of
which time there was *visible,* tho not severe, fading. After a while in
the dark, the color came back, as I recall, about half way.
What could account for the apparently greater amount of fading that
Peter's sample showed might be a different light source -- maybe their
"fade test" used an intensity of some wavelengths that don't occur under
normal conditions, and maybe the effect doesn't add up over time. In other
words, maybe it requires an intensity of such and such a level of a
particular wavelength in one dose, or in a relative brief period, to fade
the cyanotype, rather than a *cumulative* amount of these rays, which the
fade-testers theorize is accrued in 100 or however many years. Which
could explain why the Spanish sun seemed not to fade prints.
Judy