[pure-silver] Re: toning the new Adox MCC 110
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Mon, 5 Jul 2010 19:47:20 -0700
----- Original Message -----
From: "Elias_Roustom" <elroustom@xxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Monday, July 05, 2010 6:27 PM
Subject: [pure-silver] Re: toning the new Adox MCC 110
Please explain "toned to completion"
How do you konw you're done.
Also, if a print hasn't been sufficiently washed after
fixing, will that interfere with selenium toning?
Elias
"Completion" means that the print is toned long enough,
and in a strong enough solution, so that the bulk of the
silver is toned. For Kodak Rapid Selenium Toner a dilution
no weaker than 1:9 is necessary, 1:3 being better, and time
of something on the order of five minutes or perhaps longer.
Since toning is not a linear process it may be difficult to
tell when its finished but the rate of toning will
definitely slow way down after a time. When you see no
visible difference in say 20 seconds its finished.
Selenium toner does not cause a significant color
change in all material but does cause an intensification
effect, essentially an increase in the density of the
shadows in all materials. For that reason prints to be given
a substantial amount of toning should be a bit lighter or
even a bit lower in contrast than an untoned print. The
amount will vary with the material and must be determined by
experience.
Selenium toner is mainly sensitive to residual silver
and to pH. If material is sufficiently acid it may cause a
stain due to precipitated elemental selenium. This is a
peach-colored stain. Treating prints in Kodak Hypo Clearing
Agent or in any mildly alkaline bath prior to toning will
prevent this. Selenium toner will also tone silver halide
and incompletely fixed silver-thiosulfate complexes as
readily as metallic silver so its very important that prints
be well fixed before toning. This is also true of any
sulfiding toner. KRST was at one time recommended by Kodak
as an alternative test for residual silver (completeness of
fixing) because it has a longer shelf life than the standard
sodium sulfide test and does not have its rotten egg ordor.
However, the test fails where there is an abundance of fixer
in the emulsion. For materials which have been well-washed
the test works fine. Kodak recommended a 1:9 dilution in
place of the usual sulfide solution.
Note that while high dilutions of KRST (19:1) once
recommended for protection of the image from oxidation was
found not to be effective for microfilm a stronger solution
does provide complete protection. For prints or films Dr
Douglas Nishimura, of IPI, suggests using a dilution no
greater than 1:9 and toning for not less than 3 minutes at
68F. The drawback is that this will cause some change in
density and color of images. Materials for the protection of
microfilm must not cause more than a very minimal amount of
change to the crystaline structure of the image including
much change in color or density, however, this is a very
much stricter requirement than for pictorial materials.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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