Re: tonal inversion and pigment loads

I don't find any inversion in the left part of the test that I just
posted. The leftmost strip is a somewhat
pathological case with an exposure of only 1 min., but the other two
don't show any inversion, as far
as I can see. It is easy to get images without inversion. It's just that
I'm aiming for obtaining this effect
under different circumstances to try to understand it.

By the way I made the test that you recently suggested. In this image:
http://usuarios.arsystel.com/tksobota/Test-1.jpg
I have marked three zones:

zone 1 is a normal gum response to a step tablet.

zone 2 has been covered by an opaque material during exposition. It
shows an uniform stain which
makes it darker than expected.

zone 3 actually had the same stain as zone 2 above, I just removed it
while still wet so the true color
of the paper could be seen. The color of the paper is the same as under
steps 6 and 7 of the tablet,
as you can see.

Tom Sobota
Madrid, Spain

Yves Gauvreau wrote:
> Tom, Katharine et all,
>
> I would say both your test and Katharine show some inversion, whatever you
> did up to now, sizing, heavy sizing, half pigment load, extra long dev, etc.
> Any of you have an example of a step tablet print that doesn't have this
> inversion thing???
>
> Thanks
> Yves
>
> ----- Original Message -----
> From: "Tom Sobota" <tsobota@teleline.es>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Sunday, January 29, 2006 10:54 AM
> Subject: Re: tonal inversion and pigment loads
>
>
>
>> Interesting. Your rightmost test strip is equivalent to the leftmost of
>> mine, but the unexpected thing is that you got this
>> result sizing more.
>>
>> My results are quite the opposite, which is not surprising given all the
>> variables involved, many of them probably
>> unaccounted for. As I commented in a previous post, I made a test on
>> paper prepared for oil, very sized. A first coat
>> of 7% gelatine hardened in formalin plus 2 additional coats of 3%
>> gelatine. Normally you would let these two coats without
>> hardening for oil, but since I wanted to test gum, I hardened them also.
>> On this material I found only the slightest trace of stain
>> as you can see here
>> http://usuarios.arsystel.com/tksobota/SizingDifferences.jpg (the
>> leftmost three strips, which are
>> exposed 1min, 2 min and 3 min with the same mixture of Maimery Ivory
>> Black as my previous tests. The paper used
>> was Fabriano 5.
>>
>> The rightmost three strips show a very stained experiment, on Guarro
>> Watercolor paper sized with two coats of acrylic
>> gesso 10% in water. At other times I have used gesso sizing (without
>> gelatine) without problems, even if I don't like it too much
>> because it really intrudes on the texture of the paper. But this time,
>> it stained horribly. Go figure. Perhaps it is the pigment
>> with this particular gesso (Pebeo, made in China).
>>
>> My manifestations of terror of living near you were of course meant as a
>> joke. I have also never killed anyone and my friends
>> consider me a rather benign person. This is worrying, come to think of
>> it ...
>>
>> Tom Sobota
>> Madrid, Spain
>>
>> Katharine Thayer wrote:
>>
>>> On Jan 28, 2006, at 9:24 AM, Tom Sobota wrote:
>>>
>>>
>>>> Sorry, Katharine, I have posted this image some weeks before with a
>>>> clearer explanation of what it did mean. But taken out of
>>>> context it is perhaps not very illustrative. Never mind, I'll try to
>>>> organize this material better so it's easier to follow and understand.
>>>>
>>> Well, I'm pretty sure I responded to this in context when you showed
>>> it before, so maybe my response from then would be more illuminating
>>> than my present puzzlement, who knows.
>>>
>>>
>>>
>>>> Yes, living next door would be easier since surely we are looking at
>>>> the same things and calling them different names. On the other
>>>> hand, since you seem to be a woman of strong convictions, perhaps
>>>> living in Madrid is safer for me :-)
>>>>
>>> Gosh. I say what I think, but I've never yet killed anyone, or even
>>> hurt anyone; I'm not considered particularly dangerous by those who
>>> know me, and my next door neighbors aren't afraid of me, in fact they
>>> like me. So you really needn't fear for your safety living next door
>>> to me.
>>>
>>>
>>>> You know, I have been thinking about the fact that you have seldom
>>>> found inversion in your previous work. Even these days
>>>> in your tests, as far as I see, you seem to get easily pigment stain
>>>> but not inversion.
>>>>
>>>> In my case it is very different. I get inversion when I want it, with
>>>> different papers and pigments. With normal negatives and
>>>> subexposition, or with Stouffer tablets, as you have seen.
>>>>
>>>> In a nutshell, I wonder if the very different conditions of relative
>>>> humidity and temperature could make a difference. I gather that
>>>> you live somewhere on the West Coast up north, not sure if in the
>>>> U.S. or Canada, but certainly very humid. I live in a very
>>>> dry country. Gum is sensible to humidity, as Kosar dixit. It is a
>>>> wild guess, but I wonder ...
>>>>
>>>>
>>> Yes, I too have been thinking about how complex this is, and you could
>>> be entirely right about the humidiity and everything. But just to
>>> introduce more complexity into the mix, here's another wrinkle:
>>>
>>> Since the thing I was planning to do today was canceled because of the
>>> weather, I thought well, what better way to spend the day then to
>>> make a grid of test strips, varying exposure, pigment load, sizing,
>>> see if I can discover the point at which I can reliably make an
>>> inversion happen. So from the test strip I showed last night, I
>>> decided to go both ways, less pigmented and then more pigmented. First
>>> I cut the pigment in half and got a fairly good tonal scale, with
>>> almost no stain, but a very light stain. So then I thought well, this
>>> isn't a very heavy pigment load so maybe this stain really is
>>> paper/sizing related, rather than pigment-related. So I printed the
>>> same mix on a piece of the same paper I had that was sized with more
>>> than the amount of gelatin I usually use. It turned out this size was
>>> too heavy, and the emulsion flaked off right away. BUT, under the
>>> flaked-off emulsion was a significant stain, more stain than on the
>>> less-sized paper. I always seem to want to try to save an image that's
>>> disappearing, so I grabbed it and dried it fast before the last two
>>> steps flaked off, but afterward I thought that if I had left it alone,
>>> all the gum emulsion would have left and there would would be just
>>> stain and gum resist where the gum flaked off. I've tried the same
>>> mix on the same paper several more times, at longer and longer
>>> exposures, with varying (but not predictable) results, but always the
>>> stain and partial inversions where the numbers came off, and most
>>> crucially, always the flaking off of much of the gum emulsion due to
>>> the too-heavy size, which would be the ruination of this combination
>>> anyway, so there's not much point in pursuing this particular line of
>>> inquiry further.
>>>
>>> This doesn't change my current feeling that inversion is a special
>>> case of stain, and that stain is related to either paper/sizing or to
>>> pigment, but I wouldn't have thought that a sizing problem would go
>>> in this particular direction: more sizing equals more stain. I do know
>>> from experience that more sizing causes flaking, but I've never seen
>>> it cause stain at the same time. I've posted the results from this
>>> mix on normally-sized paper and the first one I did with the same mix
>>> on on the more heavily sized paper (the others are still drying) along
>>> with the more pigmented mix from last night.
>>>
>>> http://www.pacifier.com/~kthayer/html/missingnumbers.html
>>>
>>> Carry on,
>>> Katharine
>>>
>>>
>>>
>>>
>
>
>
Received on Sun Jan 29 18:40:24 2006