[Alt-photo] humidity

Bob Cornelis bob at colorfolio.com
Fri May 26 15:02:23 UTC 2017


I've looked through all the cyanotype docs on Mike Ware's site and haven't
found anything addressing my question about specific humidity
guidelines/recommendations for Ware cyanotype, hopefully I just didn't
overlook it. Took a more cursory look for pt/pd info but it seems most of
that on the site pertains to some revisions Mike has made to that process -
not sure it would pertain to the classic formula even if there was specific
humidity info (which I also didn't see).

So I'm still open to input from anyone out there who has come to some
conclusions about this. Is there a range within which you want to try to
stay? I know some people resort to humidifiers and de-humidifiers to
maintain certain levels, don't want to do this if I'm in the "safe zone",
but open to it if I'm not and it matters much.

With my pt/pd work I was taught to dry the coated paper to somewhat less
than bone dry (as opposed to cyanotype). I'm thinking that this is meant to
address the sensitivity to that process to humidity. But my methodology for
that is not very precise.

One reason I'm interested is that I'm suddenly getting radically different
(and strange) results with cyanotype on HPR in terms of how the coating is
behaving - only difference in workflow is that the humidity has gone up
about 10% in my studio since last time I worked (from 50% to 60%). Still
testing what might be going on there.


On Thu, May 25, 2017 at 11:44 AM, Keith Schreiber via
Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org>

> Not off the top of my head, but Mike has a lot of information on his
> website <http://www.mikeware.co.uk/mikeware/main.html>. I'm sure you can
> find it there.
> Cheers,
> Keith
> Keith Schreiber
> jkschreiber.com
> > On May 25, 2017, at 12:26 PM, Bob Cornelis via Alt-photo-process-list <
> alt-photo-process-list at lists.altphotolist.org> wrote:
> >
> > Does anyone know what the recommended humidity range is for
> >
> > 1) cyanotype (Ware)
> > 2) pt/pd
> >
> > I haven't found any specific info like this in any of my alt process
> books,
> > just general comments that humidity makes a difference.
> >
> > Thanks!
> > Bob
> >
> > --
> >
> > http://www.bobcornelis.com
> > _______________________________________________
> > Alt-photo-process-list | altphotolist.org
> _______________________________________________
> Alt-photo-process-list | altphotolist.org


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