[pure-silver] Re: Old Kodak Projection paper :
- From: Barrie Bunning <barrieb@xxxxxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Sat, 29 Jan 2005 06:07:42 +1100
Greetings all;
I have a few questions for the group :-
I have recently come buy 2 unopened packets of '
Kodak Kodagraph PRQ5 projection paper, it says on the label one of a
range of Kodak Document materials. It is Rough single weight, use Wratten
series OB safelight, made in England.
Q1. What color is Wratten OB ?
Q2. What developer to use.
Q3. What was the 'Original purpose' of this paper.
I have opened up one packet, in the dark, and my standard safelight seems
OK, the paper has a really rough texture, is reasonably slow to enlarge
with but seems to be similar to Grade 2. My test images are lovely, but
the paper is really thin and the base color is a little pinkish, but nice.
I have yet to try toning. Any Info would be greatly appreciated as I have
98 sheets of 20" x 16" paper that seems to be in excellent condition for
its age ? .
Cheers Barrie B.
At 04:01 PM 27/01/2005, you wrote:
>----- Original Message -----
>From: <anclancy@xxxxxxxxxxx>
>To: <pure-silver@xxxxxxxxxxxxx>
>Sent: Wednesday, January 26, 2005 8:39 PM
>Subject: [pure-silver] Re: Selenium toning question, was
>stopbath kills fixer
>
>
> > there is no need to just tone 4 11x14 and toss. it is not
> > good for the environment, and the selenium is still good.
> > as it begins to slow down, just add some selenium to the
> > mixture and continue to use.
> >
> > I haven't read the directions in a long time, so i can't
> > comment of the number of prints per ounce, but as many
> > others, i continue to use the toner, adding as needed. The
> > last time i topped off a 1:10 ratio was last year some
> > time, and i tone frequently. Don't remember the last time
> > the other ratios have had to had additional selenium
> > added.
> >
> > The directions also, indicate that one can mix the
> > selenium with HCA, which is no longer considered a wise
> > and necessary directions.
> >
> >
> > regards,
> > ann
>
> The capacity of KRST depends on the material being toned
>and on the nature of the images. Low key images take up more
>selenium from the toner so the capacity is less than for
>high key. The capicity is pretty much judged by the length
>of time it takes the toner to work. If it gets too slow add
>more concentrate as you recommend.
> The use of Kodak Hypo Clearing Agent as a diluent was
>suggested by Kodak only when the toner was highly diluted,
>say 1:20, as was previously recommended for image
>protection. The reason is that the bath then acted as a
>combination of toner and wash aid. KRST at 1:20 seems no
>longer to be a good protectant although the slight
>intensifying action may be desirable for its own sake. At
>this dilution the capacity of both toner and wash aid is
>similar. For stronger dilutions its recommended that the
>tone be diluted in plain water and the wash aid used
>separately first. The reason is to avoid the possibility of
>staining due to precipitation of elemental Selenium on the
>print due to its being acid. I doubt if this is a serious
>problem for prints or film that has been washed. Since KRST
>contains a fairly large amount of Ammonium thiosulfate
>prints can be toned directly from the toner, the hypo does
>not affect the toner. Its possible that the acid might
>result in staining from the above reason but I am uncertain
>if this happens.
> Note that Kodak at one time recommended KRST diluted 1:9
>as a test for residual silver halide in place of the older
>Sodium sulfide test. This test works on well washed material
>but fails if there is an excess of hypo. I have never seen
>an explanation of the chemistry behind this. As a test for
>completeness of fixing KRST has the advantage over Sulfide
>of being odor free and being more stable in storage.
>
>---
>Richard Knoppow
>Los Angeles, CA, USA
>dickburk@xxxxxxxxxxxxx
>
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barrieb@xxxxxxxxxxxxxxxxxxxx{ Melbourne , Australia }
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