Re: Roller for gum (was: Re: humidity in your darkroom........

Katharine,

p. 39 of his manual, and the summer thing was said in his original paper on
his website. Verbatim: "The best printing conditions are dry, low humidity
and about 20 degress celsius. Even with air conditioners and dehumidifiers
running during the hot, humid, summer here in London, Ontario, gum prints
have a muddy look to them. I do not print during this time." Perhaps he
recanted, as his website has changed since the time I found this paper (of
which I have a copy). Maybe he's so wildly successful that now he prints in
the summer, and found that his "humidity" problem has miraculously gone
away. Someone should write him and ask.

Blacklow p. 127.

As far as humidity and temp, both increase dark reaction acording to many
authors--the insolubilizing of gum at a quicker rate, without exposure to
sun.

One thing I always do is check my sources before posting to the alt list, as
I figure one way or another my head'll hit the proverbial chopping block.
Hey, maybe I don't explain things well from time to time, but as far as
research goes, as a used car salesman might say, "trust me." That's my hog
heaven.
Chris

----- Original Message -----
From: "Katharine Thayer" <kthayer@pacifier.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Tuesday, January 20, 2004 4:19 AM
Subject: Re: Roller for gum (was: Re: humidity in your darkroom........

> Christina Z. Anderson wrote:
> >
> >
> > A couple authors in books said they didn't print in the summer because
their
> > prints were "muddy" which I presume to mean either lower contrast, or
> > perhaps a higher incidence of staining possible, even, because of the
> > increased receptivity of the paper to more moisture (Livick being one).
>
> I was going to comment on this but decided first to go back and read it
> in the original source. I've looked through Livick's "book," both the
> published pamphlet and the manual he used for his online class (which he
> sent me a copy of) and can't seem to find where Livick said this in
> either one. Do you have a page number?
>
> It seems unlikely to me that Livick would say that he doesn't print in
> the summer, since he's a full time gum printer and prints in a
> climate-controlled lab. At any rate, I couldn't find any in Livick
> either in reference to not printing in the summer or to dampness
> causing lower contrast or staining. But I've probably just missed it
> somehow, so if you could give the page that would be helpful.
>
> >Blacklow says don't print in high humidity because the dichromate
> > soaks up moisture from the air and become less sensitive--either that is
her
> > conjecture or she got it from someone else.
>
> Again, I can't find this in Blacklow. I didn't study the whole book but
> I did go over the gum chaper quite thoroughly, and can't seem to see it.
>
> I did find the citations about the dark reaction from Crawford and
> Livick, but I see the dark reaction as a different issue than
> humidity. Livick deliberately keeps the humidity fairly low in his lab
> (but perhaps not as low as the air in Montana) so it seems unlikely that
> it's humidity that's causing the dark reaction that he's describing
> here:
>
> > Livick also says in his book to dry emulsion for 1/2 hour to 45 min, no
> > longer, or emulsion will start to set in the paper and highlights will
be
> > muddy.
>
> Since I print in fairly high RH (85 to 100%) most of the year, but cool,
> (here, both unusual cold, like below 20 F, and unusual heat, like over
> 85 F, are drier than the usual cool damp weather, because they both come
> on an east wind rather than from the ocean) and have no problem with
> staining, either pigment or dichromate, or other artifacts such as
> attenuated DMax, I'm inclined to believe that where people have seen
> these effects with heat/humidity, "it's not the humidity, it's the
> heat."
> Katharine
>
Received on Tue Jan 20 11:55:10 2004