[pure-silver] Re: Was Ilford -- Sulfide toners?

The following text, taken from a draft version of ?Way Beyond Monochrome¹
may answer your question:

Toning changes the image forming metallic silver to more inert silver
compounds, guarding the image against premature deterioration due to
environmental attack. The level of archival protection is proportional to
the level of image silver conversion, and anything short of a full
conversion leaves some vulnerable silver behind. ISO 18915, the test method
for measuring the resistance of toned images to oxidants, recommends at
least a 65% conversion. Nevertheless, toning causes an unavoidable change in
image tone and density. In many cases, a pronounced tonal change is desired,
because it appropriately supports the aesthetic effects intended. However,
an obvious change in image tone and density is not always suitable or
wanted. To avoid any tonal and density changes, some printers consider
toning an option and rely on post-wash treatments, such as Agfa's Sistan
silver stabilizer, alone. The image silver will likely benefit from the
stabilizer, but some toning is certainly better than none. An informed
printer makes an educated choice, balancing the aesthetics of tonal and
density changes with the benefits of image protection.
There are three commonly agreed archival toners, sulfide, selenium and gold.
The exact mechanisms of protection are not completely understood and still
controversial, but their ability to positively influence image permanence is
certain. Nevertheless, many toners contain or produce highly toxic
chemicals. Please follow closely the safety instructions included with each
product.

Sulfide Toner
For aesthetic or archival reasons, sulfide toners have been in use since the
early days of photography. They effectively convert metallic image silver to
the far more stable silver sulfide. Sulfide toning is used either as direct
one-step (brown) toning or as indirect two-step (sepia) toning. Even short
direct toning provides strong image protection with minimal change in image
color. Indirect toning, on the other hand, yields images of greater
permanence, although a characteristic color change is unavoidable. Indirect
toning requires print bleaching prior to the actual toning bath. The bleach
leaves a faint silver bromide image, which the toner then redevelops to a
distinct sepia tone. Several sulfide toners are available:
1.     Sodium sulfide toners, such as Kodak Sepia Toner, are indirect
toners. They produce toxic hydrogen sulfide gas (rotten egg smell), which is
dangerous, can fog photographic materials and is highly unpleasant if used
without sufficient ventilation. Nevertheless, this was the toner of choice
for most of the old masters. The indirect method had the added benefit of
lowering the contrast and extending the contrast range. This salvaged many
prints, which were not very good before toning, and 100 years ago, variable
contrast papers were not available.
2.     Polysulfide toners, such as Kodak Brown Toner (potassium polysulfide)
and Agfa Viradon (sodium polysulfide), can be used for direct and indirect
toning, but they also produce toxic hydrogen sulfide gas. When direct toning
is preferred, they are highly recommended for use on their own or in
combination with a selenium toner.
3.     Odorless toners, based on thiourea (thiocarbamide), are available
from Tetenal and Fotospeed. They are effective indirect toners and are more
darkroom-friendly than their smelly counterparts.
Residual silver halide, left behind by poor fixing, will cause staining with
sulfide toners. Therefore, prints must be fully fixed before any sulfide
toning. Some residual silver halide may also be left behind by indirect
sulfide toning itself, because the toner does not always 'redevelop' the
bleached image entirely. Consequently, prints must always be refixed after
indirect sulfide toning. Complete fixing eliminates unwanted silver halides.

Furthermore, residual thiosulfate can also cause staining and even highlight
loss with sulfide toners. To avoid fixer staining, it is essential that FB
prints are adequately washed prior to sulfide toning. For direct polysulfide
toning, a 30-minute wash is sufficient, and this wash is also required for
toning subsequent to selenium toning, as selenium toner contains significant
amounts of thiosulfate itself. Nevertheless, the bleaching process, required
for indirect sulfide toning, calls for a complete 60-minute wash prior to
toning. Otherwise, residual fixer will dissolve bleached highlights before
the toner has a chance to 'redevelop' them. Complete washing minimizes
unwanted chemical interactions between fixer, bleach and toner.

Some polysulfide toners have the peculiar property of toning faster when
highly diluted, and extremely dilute toner can leave a yellow or peach
colored stain in highlights and the paper base. To quickly remove toner
residue and avoid highlight staining, sulfide toning must be followed by a
brief, but intense, initial rinse before the print is placed into the wash.
Nonetheless, toning will continue in the wash until the toner is completely
washed out. To prevent after-toning and possibly over-toning, or staining of
FB prints, a 5-minute treatment in 10% sodium sulfite, ahead of washing, may
be used as a 'toner stop bath'. A treatment in washing aid, prior to the
final wash, also acts as a toner stop bath, because sodium sulfite is the
active ingredient in washing aid. For the same reason, never treat prints in
washing aid before sulfide toning, as it would impede the toning process.

Selenium Toner
This is a popular fast acting toner, used by most of today's masters,
converting metallic image silver to the more inert silver selenide and
giving a range of tonal effects with different papers, developers,
dilutions, temperatures and toning times. Selenium toner has a noticeable
effect on the silver-rich areas of the print, increasing their reflection
density and consequently, gently darkening shadows and mid-tones. This
slightly increases the paper's maximum black (Dmax) and also the overall
print and shadow contrast. For this reason alone, some practitioners make
selenium toning part of their standard routine, in an attempt to conserve
some of the wet 'sparkle', which a wet print undoubtably has, when coming
right out of the wash, but otherwise unavoidably loses while drying.
Depending on the paper, prolonged use of Kodak Rapid Selenium toner, diluted
1+4 or 1+9, makes a very pronounced effect on paper Dmax and image color.
Alternatively, a dilution of 1+19 can be used for 1 - 4 minutes, at which
paper Dmax is still visibly enhanced, but the image exhibits less color
change. Light selenium toning mildly protects the print without an obvious
color or density change. As toning continues, and starting with the shadows,
the level of protection increases and the print tones become darker and
warmer in color.
As with sulfide toners, residual silver halide, left behind by poor fixing,
will also cause staining with selenium toners, and prints must be fully
fixed before toning. FB prints also benefit from a 10-minute wash, prior to
toning, to prevent potential image staining and toner contamination from
acid fixer carryover. Prints processed with neutral or alkali fixers do not
require a rinse prior to selenium toning.
Selenium toner exhaustion is heralded by heavy gray precipitates in the
bottle, the absence of the poisonous ammonia smell and the lack of an image
change even with extended toning.

Combination Toning
Strong image protection is achieved by a combination of selenium and
polysulfide toning, converting the image silver to a blend of silver
selenide and silver sulfide, which protects all print tones. Combination
toning can be carried out by mixing polysulfide and selenium toner, creating
a combination toner, or by simply toning sequentially in both toners.
When preparing a selenium-polysulfide toner, final image tones can be
influenced by the mixing ratio. Kodak recommends a working-strength selenium
to polysulfide ratio of 1:4 for warm image tones. Adding 1 - 3% balanced
alkali will stabilize the solution, otherwise, consider the mixture for
one-time use only. As with plain, direct polysulfide toning, prints must be
fully fixed and washed for 30 minutes prior to combination toning, which is
then followed by an intense rinse and a washing aid application, before the
print is placed into the final wash.
When using selenium and polysulfide toners sequentially, final image tones
depend on toning times, as well as toner sequence. A very appealing
split-tone effect can be achieved when selenium toning is done first. The
selenium toner will not only darken the denser mid-tones and shadows
slightly, but it will also shift these image tones toward a cool blue and
protect them from much further toning. This will leave the lighter image
tones, for the most part, unprotected. The subsequent polysulfide toner then
predominantly tones these, still unprotected, highlights and lighter
mid-tones, shifting them toward the typical warm, brown sepia color. This,
in turn, has little consequence on the already selenium-toned, darker, blue
image tones. The result is an image with cool blue shadows and warm brown
highlights. This split-tone effect is most visible at highlight and shadow
borders and can be controlled with different times in each toner. As a
starting point, try a selenium to polysulfide ratio of 1:2 at 2 and 4
minutes, respectively. For this toning sequence, prints must be fully fixed
and washed for 10 minutes prior to selenium toning, and they must be washed
again for 30 minutes prior to polysulfide toning, which is then followed by
an intense rinse and washing aid, prior to the final wash.
When the split-tone effect is undesired or does not support the aesthetic
intent of the image, the toning sequence may be reversed and polysulfide
toning is done first. When selenium toning is done last, prints must be
fully fixed and washed for 30 minutes prior to polysulfide toning, which is
followed by an intense rinse, washing aid, selenium toning and the final
wash.





Regards



Ralph W. Lambrecht

http://www.darkroomagic.com







On 2005-10-26 00:26, "Eric Maquiling" <emaquiling@xxxxxxxxx> wrote:

> On 10/26 00:30, DarkroomMagic wrote:
>> consider sulfide toners, instead? Both leave you with different image tones,
> 
> Sorry Ralph and Jim for hijacking the thread.  But could you point me to some
> information on sulfide toners?  I've only started to make my own chemistry for
> about a year now.  I don't really know the difference between Selenium and
> Sulfide toners.  Perhaps you are correct about the AA influence.  I wonder
> what
> our friends in Europe and Asia use mostly?

Other related posts: