[Alt-photo] humidity

Ned Lewis nl at nedlewis.org
Fri May 26 16:19:38 UTC 2017


In Mike Ware's book "Cyanomicon", he states:

The prevailing relative humidity has very little effect on the results of
> printing in cyanotype, but it can profoundly affect some of the other
> iron-based processes.




On Fri, May 26, 2017 at 8:30 AM, forums--- via Alt-photo-process-list <
alt-photo-process-list at lists.altphotolist.org> wrote:

> In my understanding, humidity should be nearly equivalent between cyan and
> pt/pd. (I have a limited understanding of Cyanotype but this was what we
> did at MM Workshops.)
>
> HPR is especially sensitive to humidity and I recommend no less than 45%
> and no more than 66% and also to make sure your temperature is under 74
> degrees F. High humidity and high temperature can result in issues with
> this paper.
>
> Low humidity and result in even more issues though (streaking, etc). This
> paper also needs specific amounts of Tween20 or PhotoFlo (surfactants) or
> the solution will not go in properly.
>
> All in all, the variables must be tested in a scientific way before
> optimal conditions are met.
>
> best,
> Walker
>
>
>
>
> > On May 26, 2017, at 11:02 AM, Bob Cornelis via Alt-photo-process-list <
> alt-photo-process-list at lists.altphotolist.org> wrote:
> >
> > Keith
> >
> > 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.
> >
> > Bob
> >
> >
> >
> >
> >
> >
> > On Thu, May 25, 2017 at 11:44 AM, Keith Schreiber via
> > Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org>
> > wrote:
> >
> >> 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
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> >>> Alt-photo-process-list | altphotolist.org
> >>
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> >>
> >
> >
> >
> > --
> >
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