Re: acid bath for cyanotype

[Sam Wang <stwang@clemson.edu>]

> >On Thu, 23 Aug 2001, shannon stoney wrote:
> >>
> >> I tried the acid bath for the first wash with cyanotype, and it did
> >> intensify it, but it sort of worried me, because so much blue 
>came out into
> >> the bath. It seemed as if it was washing away a lot of the prussian blue.
> >
> >
> >It's possible the blue in the bath was because more blue was formed,
> >perhaps in the higher registers. Did you compare prints from identical
> >exposures?
>
>Yes, and the ones with the initial acid wash had a longer scale.  Do you
>think I should stop worrying that blue was washing out?
>
>--shannon
> >
> >J.

Shannon,

The problem with the blue being washed out is mainly that it forms a 
scum and attaches back to the paper, sometimes on the borders and 
other times on the back and is a nuisance to try to get off. I have 
resorted to a very quick immersion in the vinegar, followed 
immediately by a soak in plain water. This way you get the advantage 
of the longer scale especially in the highlights, yet avoiding having 
too much blue scum on the paper. Additionally, the same vinegar can 
be used for more prints before being discarded.

I think Judy is right that more blue is formed when you use acid 
(vinegar) rinse, by the way.

Sam