My experience with cyanotype is that I have to wash for an hour or so.
This may not apply to anyone else, though, because I print on a waterleaf
paper (Arches 88 or unsized BFK) which is totally saturated with
solution. Its a lot like blotter paper, actually.
If I do not wash it enough, over time the area around the image area will
develop a quite ugly, dirty looking stain.
It is sometimes possible to wash too long, though, and degrade the image.
Getting it right is not hard, but requires attention, and sometimes I
lose a print. I wash in one of those Arkay trays that has the water
coming in from one end and exiting through holes in the other. This is a
gentle wash. I have found that too vigorous a wash is hard on the image.
>This comes from A. Adams, Minor White, et al. We all learned our chops
>printing silver bromide and this the catechism is: wash wash wash.
Yes yes yes. In my life as photopriest I continue to intone the
canticles. But I do resist. In these days of RC papers, which I
encourage in beginning classes, washing a long time is just a senseless
waste of water.
Larry Bullis
Skagit Valley College