Selenium Toner Exhaustion
Hello Marco,
I get on my soapbox about this subject every now and then, so bear with me...
First, some things you should know about selenium toning in general and for permanence in particular: 1) only completely toned prints are fully protected. This usually means a marked color shift to red/purple brown. 2) Partial toning protects only partially and in proportion with the degree of toning. 3) Toning to increase D-max or to slightly color the print is often only a small amount of toning. 4) (This is important) Every print that you tone takes selenium out of the toner which makes it weaker, resulting in exhaustion (i.e. longer times etc.) 5) Most photographers use a visual approach to selenium toning, i.e. watching the print carefully and comparing it with an untoned print to determine the proper amount of toning. This is usually based on the amount of contrast increase/image tone change that is desired. Toning is usually not done to completion. Finally 6): Different papers tone to a greater or lesser extent depending on their composition. Some papers do not tone at all, papers developed in glycin developers tend to tone less readily, some change to a red brown, some take an eggplant color, some tone quickly, others slowly, etc.
The solution to the exhaustion problem is to simply replenish the toner by adding a bit of stock selenium toner to the toning bath. I believe that it is irresponsible to discard potentially toxic selenium when it is easy to simply replenish and reuse the same solution for years. I have a couple of gallons of selenium toner (in different dilutions for different papers) that have been going well over 2 years each. Absolutely no problems.
Now on to your specific problem: Although I am not familiar with the brand of selenium toner you are using, it seems a rather weak dilution. This means, there is not a lot of selenium in it per volume of water compared to stronger dilutions. This means 1) toning times will be comparatively longer, 2) tone change may be less noticeable, 3) the selenium in the solution will be used up faster (this is what your description leads me to believe that you are experiencing).
Now a couple of questions for you: First, Why are you toning in selenium? I.e. what tone shift are you trying to reach? If you are just toning for "permanence," but not reaching any shift of tone or increase in D-max, then you are not protecting your prints much at all.
Second, How do you know your toner is active? In other words, do you see a shift in image tone or a marked increase in contrast/D-max? If not, your toner may simply not active enough for the time you are toning to make a change or protect your prints. If you don't see a change there is simply no "archival effect" from selenium toning. This has been fairly well established. Unless you want an image change, there is no reason to selenium tone.
My recommendations:
1) Don't bother with selenium toning unless you want definite visual effect. Toning for short times in weak toner will not make much difference in the permanence of your prints (this is, indeed, a "phantom procedure" since no toning is taking place). Sulfide (Sepia) toning provides excellent "archival" protection. There is no reason to use selenium for extra protection.
2) The only practical way you can tell your selenium toner is active is if there is a visual effect. No visual change = no toning = no protection. Remember, partial toning = partial protection.
3) Tone with a suitable dilution until the desired visual effect is achieved and then pull the print. If the change is not great enough or the toning times too long, use a stronger dilution (add some stock solution to what you have). Keep in mind that some papers simply don't tone. If you like a tone change, this will factor in to your choice of paper.
4) When toning times become too long, replenish the solution by adding stock. Be careful with this at first, it is easy to add too much. Better to add three or four small amounts than overshoot and have to dilute further...
5) Don't toss exhausted selenium toner, replenish it as described above, and use it for years. Before storage and re-use, filter it through a paper towel or coffee filter to remove any sludge. A black precipitate is normal; it is toned silver that has been dissolved from your print. If you transfer directly from the fix to the toner as I do, this precipitate forms more readily since the toner dissolves some of the fixed, undeveloped halides out of the emulsion. If you wash thoroughly before toning, the precipitate is much less.
Hope this helps a bit,
Best,
Doremus Scudder
www.DoremusScudder.com