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> Selenium testing |
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#1
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Selenium testing
Since I have started to use selenium toner, mainly for archival reasons, I am wondering if there is a test. I am sure that at some stage it must become exhausted or cease to be effective. Since it has very little visual effect on some of the paper I use, especially at weak dilutions how do I know when it has reached this stage and needs replacing?
Thanks
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Ian |
#2
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Tim Rudman, suggests that the you judge how exhausted it is when the times it take to tone get very long.
As clear as mud if you can not see a change
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Mitch http://photomi7ch.blogspot.com/ If you eliminate the impossible whatever remains no matter how improbable must be the truth. |
#3
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Tony |
#4
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Presumably you use the original selenium toned print from pristine selenium and check using the same type of paper, same exposure, same print dev etc i.e, ceteris paribus and see how much longer it takes to get to the same tone. If this time is very long or worse the tone cannot be achieved even after a very long time, you then discard the toner.
Unless all things are equal it presumably becomes difficult to be sure that the selenium is exhausted? Mike |
#5
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Since selenium changes permanently the chemical status of silver in a print and more effectively so on darkest tones, it would be easy to see if your selenium bath is still active and to what extent it is by toning a print (previously treated in selenium and well washed) in a sepia/thiourea toner. You can use a scrap/test print for this purpose. If the end result is a split sepia i.e. brown highlights and gray or black dark tones, than your selenium is still effective. If it is not, the end result will be an overall brown toned print.
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#6
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I go by the smell; if it doesn't I chuck it.
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#7
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From my experience the ammonia smell of the fresh selenium bath goes off long before the bath is exhausted. Perhaps it depends on the sequence I've adopted: wet print > plain hypo 3' > selenium bath made with water and no hypo clear > hypo clear 3' > washing cycle.
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#8
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Just for clarification and in case I try selenium it may be that what you, Guiseppe and you, Dave are saying are not contradictory.
Dave, are you saying you throw the stock selenium when the smell disappears and Guiseppe are you referring to a bath that has been diluted to working strength so not the stock container that the selenium is sold in? Thanks Mike |
#9
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#10
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As a general point print fixing followed by complete washing is very important to preserve the life of selenium toner. |
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