From: Christina Z. Anderson (zphoto@montana.net)
Date: 06/19/03-02:02:00 PM Z
Judy,
Ok...you had 4-5 gums, and speeds ranged from 3-6 minutes. This did
not correlate with acidity, and hence you are saying that acidity does not
directly relate to speed of a gum.
However (now please forgive me--I am not a scientist as all of you well
know) if you are testing 4 or 5 *different* gums the reasons for speed
increase or decrease could have all kinds of causes as you say: thinness,
thickness, dark, light, type of tree exude at that time, etc. I would think
to test the acidity relating to speed you would have to only use *one* gum
and test that with added lemon juice or citric and the same pigment and the
same neg same paper side by side same day same everything. I'll do that and
report back. Have to keep disproving that Demachy character...
(btw the other night I noticed when I turned on my light in my alt room
the UV lightbox noticeably dimmed--another variable to add to the
possibilities :))
So in other words, the jury is still out, according to my limited
scientific peabrain, on this issue of acidity, the testing of the 4 or 5
gums moreso proving that *gum* speeds can differ, not that it disproves
acidity increasing gum speed.
But you are more than right about any of this testing coming up with
any hard fast rules--it just ain't gonna happen. Especially on this list
<g> I think every time I have come up with an idea it has been devil's
advocated right out of my head (there's a verb for ya).
I have learned to be very loose with gum this year after a 5 year
hiatus. Coating and exposing under room light, diginegs, development for a
couple days if it is overexposed, using colored pencils to cover up
mistakes, using powdered pigment, using a hair dryer, not sizing paper, not
being so anal with pigment measurement...the only thing I am consistent with
from before is to wear gloves always and don't drink the stuff. And I will
NEVER not preserve my gum arabic again. I have to smoke a cigar to get rid
of that rotten odor.
Chris
----- Original Message -----
From: "Judy Seigel" <jseigel@panix.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Wednesday, June 18, 2003 3:31 PM
Subject: Re: a newbie's first post: gum, temperaprint, oil printing,
sizing,and computer negatives
>
> On Mon, 16 Jun 2003, Christina Z. Anderson wrote:
> > ...I did get a pH wand so I should
> > fiddle with that and test my egg fart gum. Unfortunately, it is mixed
with
> > powdered pigment (the other colors I have are tube pigment) and I would
have
> > to mix a whole new batch of pigmented gum to test it side by side and
get an
> > even remotely usable result.
> > How much pH difference was there between the gums? What did you
finally
> > figure your speed difference was due to? How much speed difference are
we
> > talking about? Were the gums thicker or thinner and did that
contribute?
>
>
> Christina, I hate to pass up an opportunity to be definitive, but I can
> only guess...
>
> Firstly however I did test some 4 or 5 gums with a (OK guys, I may have
> the word wrong, it was 5 years ago) hygrometer -- the instrument that
> tests density of liquids. I took it to school and used the lab
> instrument, a lovely old glass and silver appliance that was beautiful if
> not helpful.
>
> All measured 14 degrees baume.
>
> The speed difference varied, and not according to the pH -- from about 3
> minutes to full range to 6 minutes -- or in a set time from 3 steps for a
> given combo to 6 or 7 steps for the same combo. However, since an
> over-exposure can often render more steps with a long soak, there IS NO
> SET POINT -- hence the answer can only be relative, not absolute.
>
> In fact, IMO you're asking for absolutes where they CANNOT exist, unless
> you make a rule of one paper, one color, one gum, and one development
> time, in which case you're throwing away much of gum's magic.
>
> My surmise was that differences in gum source and/or differences in
> preservative and/or differences in distilling method and/or difference in
> age led to difference in results. But I do not guarantee the same results
> with every color. It's probably an interaction. I simply noted it and
> adapted. (I use the slowest gum for masking, which I've written about.
> I've also noted that some gums stain more with certain sizes and colors
> than others. Yes.)
>
> Meanwhile, have I mentioned that this thinking is backwards? For good
> gumming you must lose the accustomed "photo mindset." In most alt, and
> certainly in gum, you DON'T get the chart in advance and expect the print
> to conform. And if it does conform with one combo, as soon as you try a
> new brand or new paper or whatever, it may very well disconform (just one
> reason why the gum chapter in the Ansel Adams "Guide" was so off the
> wall). You test your materials and the given combination and that's "the
> chart." Which is to say, you OBSERVE.
>
> I'll add though that it's entirely possible that with all your tools and
> zeal, YOU will come up with the answer I didn't. Hope you'll share (tho it
> may still not hold across the board). And if you do well with that PH
> wand, hope you'll share on that as well. I found it more trouble than it
> was worth... though there may be better ones now.
>
> cheers,
>
> Judy
>
>
>
>
>
>
> I have only used two gums--Daniel Smith and the one I mixed from powder
> > from Daniel Smith and then the Photographer's Formulary powder so I
don't
> > have any sort of wide experience with gum brands. Oh...no, I did break
down
> > one time and use that little jar of W+N when I ran out.
> > I should clarify that the lemon juice was for insolubilizing the
gum,
> > or hardening it without exposure, so that there would be "more stability
to
> > the halftones" (Demachy). It is used to counteract the "excessive
> > solubility of freshly prepared paper and lessen exposure..." Lemon
juice
> > will allow "...slower and surer development..."
> > He also talks about insolubilization of the gum occurring without
light
> > that happens with "..."old gum that has become acid by fermentation".
Seems
> > both provided him much the same outcome.
> > The only thing I can think of is to test this method with a
bulletproof
> > neg (I have one that has backlit windows in it behind the
> > subject--unprintable, really) but even then my puny result will probably
be
> > anecdotal and end up with the proverbial disclaimer YRMV.
> > Chris
> >
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