Re: Rethinking pigment stain

Well, that's interesting isn't it.; I don't know what to say about that
one way or the other. All I can say is that in the case of the one
tonal inversion I've looked at, which was definitely associated with a
particular concentration of burnt umber, my own experiments indicated
that it didn't have anything to do with heat or exposure, since when I
cut the coated paper in half and exposed one half but not the other, I
got the same pigment tone on the unexposed and and washed paper that I
got on the unexposed areas of the exposed and washed paper, and it
seemed to me that Tom and Joe had shown rather persuasively with their
own tests and conclusions that heat wasn't a factor.

Katharine

On Dec 14, 2005, at 10:01 AM, Yves Gauvreau wrote:

> Katharine et all,
>
> There seem to be a strong correlation between what as been called
> inversion
> on this list and heat. With most test I've made with a 500W photoflood
> I got
> inversion, as soon as I switch to a 150W plant growing lamp used at
> the same
> distance all this inversion thing was gone. Is it only because of
> heat? I
> don't know but beside the lower wattage the exposure time and all other
> params remaind the same as for the 500W bulb.
>
> Yves
>
>
>
>
> ----- Original Message -----
> From: "Katharine Thayer" <kthayer@pacifier.com>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Wednesday, December 14, 2005 12:16 PM
> Subject: Re: Rethinking pigment stain
>
>
>>
>> Well, I'm still going back and forth about this. I spent last evening
>> re-writing my page on pigment stain to reflect a broadened definition
>> of "pigment stain" including the tonal reversal as a special case,
>> but
>> you're right, there is that odd place where the paper is white, that
>> is
>> difficult to explain. Explaining it as fog doesn't work for me,
>> because when I cut the coated paper in half and put half directly into
>> water, I got the same pigment tone on that half as I got in the
>> unexposed areas on the exposed half of the paper. To me, that's more
>> like stain, and looks to be a function of excess pigment, even though
>> it's not stain in the way I always defined stain before, as an
>> indelible staining of the paper, because the sizing keeps it from
>> actually sinking into the paper. I've only seen this effect with
>> this
>> one particular pigment mix (burnt umber) and don't have time to
>> investigate it further, but I agree it's a puzzling effect.
>> Katharine
>>
>>
>> On Dec 14, 2005, at 8:25 AM, Joe Smigiel wrote:
>>
>>> Jack, et. al.,
>>>
>>> Works for me...
>>>
>>> I just wish I had a clue as to what was causing the shift. I wonder
>>> how
>>> many past prints I tossed because somewhere in the sequence of
>>> printing
>>> a multilayer gum I inadvertantly introduced this reversal shift and
>>> later thought it was an inexplicable random effect, that I didn't
>>> live
>>> right, or was a bad person, etc. Glad to clear that all up.
>>>
>>> I'll be vary wary of using any black or neutral tint until I test it
>>> for
>>> this effect.
>>>
>>> Joe
>>> ___
>>>
>>>
>>>>>> jack@jackbrubaker.com 12/14/05 10:53 AM >>>
>>> Joe,
>>>
>>> I think your definitions of fog and stain make sense in gum and are
>>> consistent in other media. I agree we need a term for the effect you
>>> describe below. How about calling it what it does (since we don't
>>> know
>>> what
>>> it is caused by). Using your words, "reversal shift" would seem to be
>>> a
>>> clear enough term for what is apparently a uniquely gum problem. Or
>>> perhaps
>>> "gum reversal shift" to make clear that it is just for gum.
>>>
>>> Jack
>>>
>>>> From: Joe Smigiel <jsmigiel@kvcc.edu>
>>>> Reply-To: alt-photo-process-l@sask.usask.ca
>>>> Date: Tue, 13 Dec 2005 22:36:20 -0500
>>>> To: alt-photo-process-l@sask.usask.ca
>>>> Subject: Re: Rethinking pigment stain
>>>>
>>>> The
>>>> reversed areas shift about depending on the level of exposure, yet
>>> there
>>>> seems to be an intermediate exposure that leaves the paper white
>>> without
>>>> pigment stain. It does not appear to be a random effect although I
>>>> can't explain it.
>>>>
>>>> Perhaps there would be a better term than "fog" to describe it, but
>>>> in
>>>> my opinion, it is not "stain."
>>>
>>>
>
Received on Wed Dec 14 12:57:58 2005