Re: Tonal inversion (was (Gum) Tonal scale)

From: Christina Z. Anderson ^lt;zphoto@montana.net>
Date: 12/03/05-10:13:01 AM Z
Message-id: <003101c5f824$ce44e5a0$736992d8@christinsh8zpi>

Good morning!
First of all, Tom, I loved your mask images. Both are equally effective but
i do prefer the golder one because the gold really looks like gold!

Second of all, the reverse tonal palette:

yes, we talked about this on list not last summer but summer 2004...I was
testing the addition of lemon juice to the gum mix to see if it lengthened
the tonal scale, etc., following a recommendation by Demachy.

What I found was this reverse solarization effect that Judy had previously
described. The more acid added, the stronger it became. It was not because
I added more fluid and the gum coat was more diluted, because I balanced
added drops of lemon juice with added drops of water.

I figured that Judy and Mike Ware were correct, that staining was held back
by a partially hardened gum, so that pigment was unable to sink into the
paper fibers.

I also felt that the acidity factored in--the more acid, the more what I
might term "mordanting" of the color to the paper surface. Whether the acid
destroys the paper sizing as Joe has suggested or some other attraction
factor is at work, I don't know.
Chris

----- Original Message -----
From: "Tom Sobota" <tsobota@teleline.es>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Saturday, December 03, 2005 3:36 AM
Subject: Re: Tonal inversion (was (Gum) Tonal scale)

> Joe,
>
> This 'solarization' happens, I have seen it mostly with blacks under
> high density areas of the negative. But sometimes with other colors too.
>
> Years back I was using x-ray film, which was double coated and had
> a very high D-Max and this value inversion happened frequently.
>
> It was driving me crazy so I stopped using x-ray film which was
> a very good idea...
>
> Have a look at this test strip, printed with lampblack (0.03g in 2cc
> gum solution + 2cc Amm.Dichromate 30%, paper twice sized
> with gelatine)
> http://usuarios.arsystel.com/tksobota/Lampblack_strip.jpg
>
> I have exaggerated somewhat the contrast so the effect is
> easier to see. In the original, all the steps of the three strips
> are distinctly visible and separated.
>
> I have no explanation for this effect, but I think that it has
> been mentioned on this list some time back.
>
> Your idea about the muddied water and pigment migrating
> could be perhaps tested developing a test strip under slowly
> running water, instead of the usual 'stand' developing.
>
> Tom
>
> At 02:42 03/12/2005, you wrote:
>>No big surprises here except the curious response of the Bone Black
>>pigment test (bottom middle). Take a look at the circles around the
>>numbers and step areas 14 and higher. There is definite pigment stain
>>in those areas which should be paper white. It is as if there is a sort
>>of pigment stain solarization effect happening. Steps are
>>differentiated from about step 6 through step 13 and then the steps
>>print darker due to pigment stain. I speculating that a very small
>>amount of exposure has caused steps 12 & 13 to print almost paper white.
>> I'm thinking the slightly exposed gum there has reduced pigment
>>staining which perhaps has occurred during wet processing. IOW, as the
>>prints autodevelop in water, this particular pigment is released from
>>all areas of the print to some degree and it muddies the water. Where
>>an exposure hasn't had any effect at all, the pigment migrates to the
>>unprotected paper and stains it. This is only happening under the gum
>>though. Areas outside the coating remain unstained and protected by the
>>gelatin size. Somehow the emulsion has caused the areas beneath to
>>stain disproportionately, perhaps by adversely affecting the sizing or
>>somehow interacting with it and weakening it. Has anyone else seen this
>>before or have an alternate theory of why it has occurred?
>>Joe
>
>
>
Received on Sat Dec 3 10:15:52 2005

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