Longevity of selenium

[domenico Foschi]

Can anybody tell me the longevity of selenium toner undiluted stored in half full bottle?
Thank you.
www.dfoschisite.com

[Andrew O'Neill]

A few months and then it starts getting yucky. I've found that the more dilute the selenium is, the shorter its shelf-life. Edge of bottle becomes blackened. All the black crap floating around can also be strained out. Seems to fair a bit better in a glass bottle.

[Wayne]

I just used 5 year old diluted toner a few weeks ago and it looked/worked fine, so I have to think undiluted toner could potentially last a long time too. Could, not necessarily will. My undiluted half-full toner of the same age still looks fine, but I havent tried it.

[paulr]

i've used it many years old (stored undiluted) and a couple of years old (diluted 1:20). never noticed any changes. not a scientific study ... just lazy processing that ended up working out fine.

[John B.]

I've used Kodak RST that was first opened over 20 years ago. Worked fine. I am under the impression this stuff lasts (undiluted) forever.

[Doremus Scudder]

Domenico and the rest of you:

Selenium lasts indefinitely. If a black precipitate or scum forms, filter it off by pouring the solution through a paper coffee filter.

It is best not to discard selenium toners if you absolutely do not have to. Selenium is a heavy metal and toxic. I have gallons of selenium toner that I have been using and replenishing for years. No problems whatsoever.

If you must discard the solution, use it to the point of exhaustion and then toss a few old discard prints in the solution and let them sit for a day to trap the remaining selenium. The resulting solution should be dilute enough to not be much of a problem.

If you are tossing active selenium toner just because it has a precipitate or scum, you are not only being wasteful, but also environmentally unfriendly.

Best,

[Scott Davis]

actually, if you have some old selenium toner (diluted) sitting around that is exhausted for printing purposes, you can pour it on the plants in your flower garden. They'll love you for it. This is NOT environmentally unfriendly. The plants absorb it, and it helps them grow- just as you need trace amounts of selenium in your diet, so do they.

[Ron Marshall]

It is alright to pour it on flowers, just don't pour it on anything you plan to eat.

[paulr]

there's a lot of misinformation about selenium toner.

selenium is not a heavy metal, nor is it a metal at all. it's a chemical relative of sulfur. trace ammounts are a vital nutrient, but it is quite toxic in large doses. any ingestion of it in the forms used in photography would be considered a very, very large dose. i can't imagine recommending that anyone water their plants with it. trace amounts in the soil might be good for some plants; a deluge of high concentration sodium selenite is environmental polution. if you're anywhere near the groundwater or if you have a well on your property, this is pure recklessness.

some toxicity information is here:

http://www.atsdr.cdc.gov/tfacts92.html