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  #1  
Old 10th May 2012, 12:28 PM
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Ian Marsh Ian Marsh is offline
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Default 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?

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Old 13th May 2012, 10:56 AM
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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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Old 13th May 2012, 06:37 PM
Tony Marlow Tony Marlow is offline
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Quote:
Tim Rudman, suggests that the you judge how exhausted it is when the times it take to tone get very long.
Looking at a print on its own and you may not notice a change but if you put a toned print alongside an untoned print then the change is quite noticeable if the selenium is working. The toned print does look cleaner and blacker.

Tony
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Old 13th May 2012, 09:29 PM
Mike O'Pray Mike O'Pray is offline
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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
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Old 26th May 2012, 04:52 PM
Giuseppe Giuseppe is offline
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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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Old 26th May 2012, 05:29 PM
Dave miller Dave miller is offline
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I go by the smell; if it doesn't I chuck it.
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Old 27th May 2012, 07:42 AM
Giuseppe Giuseppe is offline
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Quote:
Originally Posted by Dave View Post
I go by the smell; if it doesn't I chuck it.
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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Old 27th May 2012, 04:57 PM
Mike O'Pray Mike O'Pray is offline
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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?

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Mike
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Old 27th May 2012, 05:34 PM
Giuseppe Giuseppe is offline
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Quote:
Originally Posted by Mike O'Pray View Post
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
I am referring to a working solution made up by mixing the selenium stock normally sold with water (usually in a 1+9 strength).
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Old 27th May 2012, 05:41 PM
Dave miller Dave miller is offline
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Quote:
Originally Posted by Giuseppe View Post
I am referring to a working solution made up by mixing the selenium stock normally sold with water (usually in a 1+9 strength).
Same here, although I use it between 1:3 and 1:40. I find my noise to be a good indicator when the stuff is on it's last legs. I only now use the Kodak brand so others may differ.
As a general point print fixing followed by complete washing is very important to preserve the life of selenium toner.
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