Richard Knoppow is the expert on this. I believe he a paper on it somewhere in his files. But regardless, he is the one to contact. From what I remember, you have the facts right.
am sure Ryuji can provide the specific date of the papers, as this was discussed in depth a month or so ago on pure-silver.
as i remember he provided a lot of data. i thought i saved that particular thread but will have to go search around in other files.
And as always Ole is correct.
A quick Google search turned up the following info. I'll follow up on the suggested pure-silver articles to see if the thinking has changed.
From Lloyd Erlick’s website (1998 article)
Selenium itself is not particularly toxic. . .The problem with selenium is that it reacts with other substances to form soluble reaction products which are toxic. When it reacts to form insoluble reaction products, they tend to be less toxic. A good example is silver selenide, which is formed on a photographic print as it is being toned. The color we see in a selenium toned print is the color of silver-selenide coating the microscopic particles of silver metal we have in our print. It's very fortunate that humans find this color agreeable, because this selenide coating (or plating) on the silver particles also protects the silver from many substances that would react with it and degrade the image. Sulfur dioxide, a common air pollutant, is a good example.
What toners do is convert metallic silver to a silver sulfide or to a silver selenide creating an inert compound that significantly reduces the effect of oxidizing agents that may reduce the life of a black and white print. Selenium toner converts metallic silver to a silver selenide for greater image stability. . .Selenium toner when used for archival permanence ( 1 part Kodak Rapid Selenium Toner + 39 parts water and left in solution for 10 minutes ) will halt the ravage of time with no appreciable shift in color.
I've studied that IPI paper. It should be made clear that their
Originally Posted by Maine-iac
concern is with microfilm.
Here is your new trick for today. For complete protection
prepare a .01% solution of Na2S, sodium sulfide, then soak
the print in that solution. The IPI paper did not suggest
any times. I'd think 3 or 4 minutes would do.
If paper and microfilm silver are similar than the 1:9,999
solution will give very good archival protection.
IIRC, the matter of selenium's value as an archival treatment
is wholely concerned with microfilm. There may be no studies
of it's worth where papers are the subject. Dan
Sorry, just can't take it anymore....
Returning to the original question, we have now explored the possible sources for ammonia smell. For what was really asked about (see title of thread), I have no answer. And unfortunately Hogwart's isn't on email, so it's difficult to get in touch with them.
-- Ole Tjugen, Luddite Elitist
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Either from rapid fixer or selenium toner.
Both have Ammonium Thio and either a strong alkali or chlorine make the Ammonia airborne
Nothing to worry about thogh, very good for colds and sinus
Mama took my APX away.....
Microfilm and enlarging papers are fairly similar. There are differences but then I would say variations among enlarging papers is also large. If you are serious about archival concern, I would say you should consider all weakness found for microfilm as well as other silver material in order to enhance the permanence of your prints.
Originally Posted by dancqu
There are studies about enlarging papers, duplicating films, and other materials from various labs, including Eastman Kodak, RIT, national museum of Denmark, etc.
Protection from selenium toning is useful if the conversion is pretty complete. Even this is a vague statement and the actual benefit depends on a lot of variables. One study I know looked at the image degradation after oxidation treatment versus degree of conversion. The minimum conversion necessary to achieve a certain level of protection varied a lot depending on the emulsion. Even among pictorial material.
Originally Posted by Maine-iac
The problem is no one knows what physical/chemical parameter in the emulsion is correlated with this result, so one can't simply predict the permanence from speed, brand, etc, etc. On the other hand, polysulfide treatment is more consistent and sure-fire.
Another problem is that selenium toner left in the print is just as harmful as residual fixer. Prints must be washed thoroughly after coming to contact with toning agent.
Given proper toning and washing, the permanence will be increased, but probably not as much as we would like, and not as much as what we could get from polysulfide toner.
Originally Posted by kwmullet
There are studies. Specifically, I've not seen one concerned
Originally Posted by Ryuji
with selenium and FB paper. Never the less, nothing tops sulfide.
The IPI gives reasons for the use of polysulfide rather than
sodium sulfide. None of those reasons has anything to do with
sodium sulfide's effectiveness as an archival treatment. They
do not spell out their reasons for mentioning the polysulfide.
Drum quantities is likely a factor, manufacture, and S&H
are likely others.
They do say that sodium sulfide affords complete archival
protection at a 1:9,999 strength; 0.01%. in solution. Dan