Re: Rethinking pigment stain

On Dec 14, 2005, at 1:36 PM, Tom Sobota wrote:

> I was commenting on Dave's opinion that '"fog" is a misleading term',
> which implies that we pretty much _don't_ all agree on what fog is.

Fair enough; I was reading Dave's remark to mean simply that he didn't
think fog was often encountered in usual practice with gum, a remark I
agree with, but yours is a more literal and for all I know more
accurate reading.

>
> As my use of "global insolubilization", it means the following:

I didn't say I didn't understand it; "global insolubilization" pretty
much defines itself. I just said I found it an awkward mouthful,
meaning not a very graceful phrase, and I wouldn't be likely to use
that particular verbal construction myself, as it seems ugly to me in
a prosodic sense, quite apart from its meaning, much like the
bureaucratic words like "eligibilize" etc.

  But on reflection, I find I don't even agree with the phrase as a good
definition for fog. While there are some types of fog, such as the dark
reaction, that will probably always present as a global
insolubilization, there's no particular reason why inadvertent exposure
can't affect a part of the coating without the entire thing being
fogged, or that it can't crosslink enough of the gum to partially
harden the coating without rendering it completely insoluble.

I'm going to make a liar out of myself now by recalling a second
example of fog from my own experience, after I said I'd only seen it
once, but one can't remember everything all the time, especially when
you're as old as I am and have as many things to remember as I have. At
any rate, one time a stray ray of weak sunshine found its way between
the pine trees and the garage and the guest cottage and the house into
the studio to cast onto the drying table a dim shadow of the
windowframe, so dim I didn't even notice it as I was drying the
coating. But it had already printed itself into the coating, and
spoiled the subsequent print. I would call this fog. It was
inadvertent formation of crosslinked gum, but it certainly wasn't
global insolubilization (not only did it only affect the parts of the
coating that the sunlight actually fell on, but the intentional print
printed on top of it, so the gum obviously wasn't completely
insolubilized, even in the areas where the coating was fogged.

So I'm going to stick with my wording, not only because I like the
sound of it better, but because it means exactly what I mean by fog,
and "global insolubilization" does not. But perhaps I should
specify, though it seems to me it should go without saying, that I am
not imposing my definition on you or anyone else, just telling you why
it's the one I will use myself, personally.

>
>
> This is the term I prefer, but I'm not imposing it upon anyone,
> so if you want to say "inadvertent (meaning non image-related)
> formation of crosslinked gum" instead of "global insolubilization",
> that's just fine with me. I would only object on the use of
> 'inadvertent'
> as a synonymy for 'not image-forming'. But hey ...

Actually, I said "not image-related" rather than "not image-forming."
inadvertent means "not intentional," meaning not related to the image
that is being intentionally printed. But fog can certainly be
image-forming, as in the case of the image of the shadow of the
windowframe that printed itself perfectly onto my print.

>
> Again, whether fog happens more or less frequently in actual
> practice is not an impediment for having a definition for it, in my
> opinion.
>

I agree; earlier today I thought we all pretty much agreed on a
definition, but now I see that we don't.

Katharine

>
> At 17:43 14/12/2005, you wrote:
>> I think we pretty much agree on what fog is, although I would never
>> use the phrase "global insolubilization;" that seems a rather awkward
>> mouthful to me. I'll continue to use the phrase I've been using; to
>> me fog is the inadvertent (meaning non image-related) formation of
>> crosslinked gum, and, as I said in my response to Joe's lexicon last
>> week or whenever that was, in my mind it includes the dark reaction.
>> I don't know about the "continuing reaction" I've never seen that
>> myself.
>>
>> I thought Dave's point was, how often do we ever see fog in actual
>> practice? I've only seen it once, when I left a coated paper sitting
>> by a window and went off to get something. And I've only seen fog in
>> the form of the dark reaction once, when I deliberately left coated
>> paper in the dark to see if it would happen (it did), but I've never
>> seen it in practice, because I always coat and dry one paper at a
>> time and expose immediately.
>> Katharine
>>
>>
>>
>> On Dec 14, 2005, at 7:08 AM, Christina Z. Anderson wrote:
>>
>>> Right on, Tom,
>>>
>>> fog = global insolubilization of the gum layer...
>>>
>>> I'll add to your list one thing they used to say but I have never
>>> found to
>>> be true is they used to say certain pigments produced as they termed
>>> it
>>> "spontaneous insolubilization of the gum".
>>>
>>> I could say that when I was doing 8 large gums at once down in South
>>> Carolina where the humidity was higher, the last print to go into
>>> the water
>>> would take longer development to remove nonimage "fog". Fog, up to a
>>> certain point in gum practice, usually doesn't make too much
>>> difference
>>> because it is removable, unlike silver gelatin.
>>>
>>> Does this fog, then, form an umbrella over the two terms of "dark
>>> reaction"
>>> and "continuing action"? Because both result in global, non-image
>>> insolubilization. In other words, back in "the day" (1800's-1900's)
>>> they
>>> didn't term it fog in the first place but used these two terms to
>>> describe
>>> this global insolubilization.
>>> chris
>>>
>>>> It all depends on how you define 'fog'. To me, fog is a global
>>>> hardening or insolubilization of the gum-dichromate layer which
>>>> does not contribute to the formation of an image.
>>>>
>>>> It can be produced by any (or a sum of) several causes, among which
>>>> accidental exposure to light too, of course. Others are heat,
>>>> exposure
>>>> to chemicals, and the simple passing of time. Surely others.
>>>>
>>>> The normal exposure to light of a layer of dichromated gum under
>>>> a negative produces a hardening which is not physically different
>>>> from a fog-producing exposure to light, but it produces an usable
>>>> image
>>>> since it is not global but rather differential. So we don't call it
>>>> fog.
>>>>
>>>> This loose definition of fog could be applied to silver-gelatin
>>>> emulsions
>>>> too, actually.
>>>>
>>>> Pigment stain is different, and perhaps unique to gum, carbon and
>>>> other processes using finely ground particles of pigment.
>>>>
>>>> But dichromate stain has a sort-of analogue in silver-gelatin
>>>> emulsions
>>>> when you develop with pyrogallol or pyrocatechol, for example, which
>>>> also produce stain. This stain contributes to the image, however,
>>>> because
>>>> it is in the negative and not in the positive.
>>>>
>>>> If you want to see fog in gum, coat a paper and keep it in the dark
>>>> for a
>>>> week or two in a warm place. Then develop side by side with a
>>>> just-prepared emulsion. The relative darkening of the older coat
>>>> should
>>>> be evident.
>>>>
>>>> Tom Sobota
>>>> Madrid, Spain
>>>>
>>>>
>>>> At 03:38 14/12/2005, you wrote:
>>>>> I don't know all the details regarding that past discussion, but I
>>>>> think
>>>>> "fog" is a misleading term. I consider fog to be accidental
>>>>> exposure,
>>>>> e.g.
>>>>> someone opens the back of a 35mm camera and the film gets "fogged".
>>>>> Perhaps
>>>>> gum paper can get fogged from ambient light levels being too high
>>>>> in the
>>>>> darkroom, but I've never had that problem.
>>>>>
>>>>> Dave Rose
>>>>> Powell, Wyoming
>>>>>
>>>>> ----- Original Message -----
>>>>> From: "Katharine Thayer" <kthayer@pacifier.com>
>>>>> To: "alt photo" <alt-photo-process-l@sask.usask.ca>
>>>>> Sent: Tuesday, December 13, 2005 12:16 PM
>>>>> Subject: Rethinking pigment stain
>>>>>
>>>>>
>>>>> > Hi gum printers,
>>>>> > Because for most of my gum printing career I've printed on
>>>>> unsized
>>>>> > paper, I developed a definition of pigment stain that I realize
>>>>> now
>>>>> > probably applies mainly, if not exclusively, to printing on
>>>>> unsized
>>>>> > paper. My definition required that in order for something to be
>>>>> called
>>>>> > pigment stain, the pigment had to penetrate the paper and be
>>>>> indelible.
>>>>> > And in my experience, when pigment stain occurred, it occurred
>>>>> > immediately when the coating was applied; if the pigment was
>>>>> excessive
>>>>> > in relation to the gum, it would stain the paper immediately on
>>>>> > application.
>>>>> >
>>>>> > The tonal inversion thing made me rethink that idea, as I said a
>>>>> couple
>>>>> > of days ago, and after doing some experiments with sized and
>>>>> unsized
>>>>> > paper, I've decided I need a more inclusive definition that
>>>>> > incorporates what happens on sized paper, or maybe two different
>>>>> terms;
>>>>> > I haven't decided yet for sure.
>>>>> >
>>>>> > A more inclusive definition for "pigment stain" would say that
>>>>> pigment
>>>>> > stain is whenever you get pigment in places where it shouldn't
>>>>> be,
>>>>> > such as in unexposed areas of an image or step print. Whether
>>>>> or not
>>>>> > that out-of-place pigment forms an indelible *stain* will be a
>>>>> function
>>>>> > of how well the paper is sized. On sized paper, this "stain"
>>>>> will wipe
>>>>> > off easily, whereas on unsized paper it will be indelible, but in
>>>>> > either case, you've got pigment you don't want in areas that
>>>>> should be
>>>>> > very light or paper white, hence: stain.
>>>>> >
>>>>> > One problem with this more inclusive definition is that it
>>>>> doesn't
>>>>> > distinguish between stain and fog. Someone referred recently to
>>>>> a
>>>>> > discussion from last summer where Mark showed a gum test print
>>>>> where
>>>>> > there was color on areas where the print should have been paper
>>>>> white.
>>>>> > I called that stain, and was told that it was fog. I conceded
>>>>> the
>>>>> > point; when told that it could be wiped off the paper I assumed
>>>>> (given
>>>>> > my then understanding of stain) that it couldn't possibly be
>>>>> stain and
>>>>> > must be fog, although I didn't have a clear understanding of
>>>>> what could
>>>>> > have caused the fog. And when that was brought up recently, I
>>>>> > acknowledged I'd been wrong when I'd called it stain. But now
>>>>> that I
>>>>> > have seen for myself that pigment stain can also be easily wiped
>>>>> off
>>>>> > sized paper, (while still wet, of course) I'm not sure I know
>>>>> how to
>>>>> > tell the difference between stain and fog on sized paper.
>>>>> >
>>>>> > They are of course different in substance, because what I would
>>>>> call
>>>>> > "pigment stain" is just pigment, since it occurs in areas where
>>>>> no
>>>>> > exposure, and therefore no formation of crosslinked gum, has
>>>>> occurred,
>>>>> > whereas fog, in my opinion, would involve the formation of
>>>>> crosslinked
>>>>> > gum.
>>>>> >
>>>>> > On unsized paper, excess pigment impregnates the paper as
>>>>> stain, and
>>>>> > that's why it stays with the paper rather than dissolving away
>>>>> with the
>>>>> > dichromate and soluble gum from unexposed areas. But on sized
>>>>> paper,
>>>>> > even though the pigment isn't held in the paper as stain, or in
>>>>> > crosslinked gum as "tone" it still remains on the paper in
>>>>> unexposed
>>>>> > areas, as seen in the examples of "tonal inversion." This is
>>>>> > interesting, but puzzling, to me. At any rate, I've satisfied
>>>>> myself,
>>>>> > by cutting coated papers in half and exposing one side and
>>>>> putting the
>>>>> > other side directly into water, that the "pigment stain" is the
>>>>> same
>>>>> > on unexposed areas of exposed coatings as it is on completely
>>>>> unexposed
>>>>> > paper, whether sized or unsized, which makes me even more
>>>>> confident
>>>>> > that the effect has nothing to do with exposure, heat or
>>>>> anything else
>>>>> > related to the exposure itself, but is simply pigment stain.
>>>>> >
>>>>> > Thoughts, anyone? I will soon be revising my page on stain, lord
>>>>> > willing and the creek don't rise, to reflect the evolution of my
>>>>> > thinking on this topic.
>>>>> > Katharine
>>>>> >
>>>>> >
>>>>
>>>>
>>>
>
>
Received on Thu Dec 15 00:02:56 2005