How does selenium do it?

"Lew" wrote:

Can anyone explain how the same toner can have opposite effects
on different papers? I'm referring on krst's ability to cool off
cold tone papers and warm up warm tone papers while, iirc, helping
with the dmax of both.

Regarding only the "dmax" part of your question, according to Stephen
Anchell in The Darkroom Cookbook (2nd Edition, p. 96) the act of selenium
toning a silver print converts the metallic silver in the print into silver
selenite, which "has a deeper maximum black than metallic silver."

The various color changes themselves are enumerated and described, but not
explained in depth.

Ken

From the book:

"Selenium toners, such as Dassonville T-55, convert the silver to [silver]
selenite (examples of commercial selenium toners are Berg Selenium toner and
Kodak Rapid Selenium Toner).

"Selenite is impervious to almost all environmental pollutants, with the
added benefit that, at dilutions of 1:20 or greater,* it will not effect
image tone. Not only that, but selenite has a deeper maximum black than
metallic silver, enhancing the richness of the shadows.

* "The dilution is paper dependent. Some papers can stand a much lower
dilution, some require more."

Good enough on the dmax issue. . Since silver selinite is silver selinite
regardless of whether the underlying paper is warm toned or cool toned,
we're left with the cool-cooler, warm-warmer part. Why don't all papers
just tend toward silver selinte tone as toning increases?
Thanks.
-Lew

Lew wrote:

Since silver selinite is silver selinite... Lew


As with sulf-IDE it is selen-IDE. Sulfur and Selenium
are two very similar elements. As a solution of sodium sulfide
will produce silver sulfide, a solution of sodium selenide
might be expected to produce silver selenide.
Search this NG for, selenium selenite . Dr. Gudzinowicz as
well as others offer some good information. Dan

G- Blank wrote:

In article ,
Tom Phillips wrote:

David Nebenzahl wrote:

G- Blank spake thus:

Lew wrote:

Can anyone explain how the same toner can have opposite effects
on different papers? I'm referring on krst's ability to cool off
cold tone papers and warm up warm tone papers while, iirc,
helping with the dmax of both.

It has a lot to do with the specific chemistry of the
paper and toner interaction. This can be a result
of how finely the silver is milled that a specific paper
is made from, or the type of paper. Length of time in the
toner, water chemistry (as in ph and mineral content) and toner
dilution- probably infinite variables could be had with non delineated
print making criteria.

In other words, "I don't know".

A lot like most of your posts...

The problem is there is no definable set of circumstances as the
question was asked, quite a few "borderline" "photographers"
notoriously ask these nebulous questions without doing the
math-research-testing themselves and then BITCH because they get a less
than concise answer. I could have flatly answered "NO" there is noway
based on the flawed way you asked the question to define the outcome
but chose to try and get him to think-Oh well I guess somethings
just don't work. I don't typically take the attitude that people owe me
but I will say I have tested a **** load more paper and chemistry
than all but perhaps a few here will ever test. Like in 100's-1000's of
emulsion batches.

FWIW I did give a concise answer given the info he provided.

What Nebenzahl derides Nebenzahl doesn't understand...

And as far as David is concerned if he could make a valuable
contribution to this or other ng's it might be worth my time to
unkill file him,..... but it won't happen ;^)

r.p.d slide downhill the moment he began gracing
it with his derisive presence. I'm sure he
considers that his most valuable contribution
as he's clearly proud if it.

Did you notice how a new trend seems to be creating their "cute"
little political sigs...........

Seems to parallel the trend to remake r.p.d and
r.p.e.LF in their own image...

"Lew" wrote in message
...
Can anyone explain how the same toner can have opposite
effects on different papers? I'm referring on krst's
ability to cool off cold tone papers and warm up warm tone
papers while, iirc, helping with the dmax of both.
-Lew
The color of the original image and the color of the
toned image are both dependent on the size and structure of
the silver crystals. In general (meaning with some
qualifications), the coarser the crystals the bluer the
image color. Extremely finely devided silver (colloidal
silver) is bright yellow. In fact, the yellow filter layer
in Kodachrome is made of colloidal silver. When toned the
structure tends to remain the same as the original. So, the
Silver selenide resulting from Selenium toning will be
bluish or purple on cold tone papers and on film and more
red or yellowish where the original silver is finely
devided. Sulfiding toners are similar, the coarser the
original the colder the brown. In fact, Polysulfide toners,
like Kodak Brown Toner, result in a slight cooling of the
color of microfilm when used to protect the image. This is
because the color of Silver sulfide is also dependent on the
structure of the crystals.
Very cold tone papers are usually toned by bleaching them
first and then treating them in a sulfide bath. The image
color still depends somewhat on the original color but not
so directly because the original silver is converted back to
a halide by the bleach before toning. Direct toners, like
KBT or Kodak Selenium toner, tend to preserve the original
size and distribution of the image silver.
KRST and some other toners (Gold for instance) intensify
the original image. This is NOT because they are "blacker"
then the original silver but because they add to the
covering power of the silver by increasing the size of the
grains a little. Actually, silver can be used for
intensifying, for instance Kodak In-5. This intensifier
increases density without chaning image color.
Indirect Sepia toners (bleach and redevelop type) can
also be intensifiers provided that there is absolutely no
hypo remaining in the emulsion. Any hypo will combine with
the bleach to form Farmer's reducer and will slighly lower
the density rather than increase it.


--
---
Richard Knoppow
Los Angeles, CA, USA

Thanks for taking the time, Richard. This is a thorough, clear and
considered explanation.

-Lew

"Lew" wrote in message
...
Thanks for taking the time, Richard. This is a thorough,
clear and considered explanation.

-Lew
Looking at it again I think it might have been clearer if
I had included something about the light being scattered by
the particles which make up the image. It is the scattering
and interference of different wavelengths that produces the
color. While we see "grain" in both negatives and prints the
actual silver crystals are microscopic. The apparent grain
is due to grouping of the individual particals, either
actual clumping or the appearance of clumps from grains at
different depths of the emulsion. Both the size and
distribution of the individual silver particles and "clumps"
affect the image color. Toning further changes the
structure.
Some materials used in toners have an actual color. For
instance, the blue generated by Iron-blue toner. This is
similar to the material of which blue prints are made.


--
---
Richard Knoppow
Los Angeles, CA, USA

Well, I can't accept your criticism of your original answer, but I
appreciate the additional information.
-Lew
"Richard Knoppow" wrote in message
link.net...

"Lew" wrote in message
...
Thanks for taking the time, Richard. This is a thorough, clear and
considered explanation.

-Lew
Looking at it again I think it might have been clearer if I had included
something about the light being scattered by the particles which make up
the image. It is the scattering and interference of different wavelengths
that produces the color. While we see "grain" in both negatives and prints
the actual silver crystals are microscopic. The apparent grain is due to
grouping of the individual particals, either actual clumping or the
appearance of clumps from grains at different depths of the emulsion. Both
the size and distribution of the individual silver particles and "clumps"
affect the image color. Toning further changes the structure.
Some materials used in toners have an actual color. For instance, the
blue generated by Iron-blue toner. This is similar to the material of
which blue prints are made.


--
---
Richard Knoppow
Los Angeles, CA, USA

"Richard Knoppow" wrote

Some materials used in toners have an actual color. For
instance, the blue generated by Iron-blue toner. This is
similar to the material of which blue prints are made.

Often called 'Prussian Blue', Iron(III)-hexacyanoferrate(II),
is/is related to/ the blue that forms when Farmer's reducer goes off.

The origin of color of Prussian Blue is an electronic transition
from a low-spin Fe2+ ion in a carbon-coordination center to a
high spin Fe 3+ ion in a nitrogen-coordination enter that occurs
when visible light is absorbed at 680nm. This absorption is
called the intervalence transfer band which produces the intense
color of Prussian Blue.

Like I knew that all along....

Cribbed from:
http://www.sewanee.edu/chem/Chem&Art.../Prussian_Blue

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.
To reply, remove spaces: n o lindan at ix . netcom . com
Fstop timer - http://www.nolindan.com/da/fstop/index.htm