I toned some prints tonight...Polymax FB and Bergger VCNB...and thought I had them just right when I took them out of the selenium. I put them in water and then the wash, and by the time they were in the wash they were lavender.
I have such a hard time seeing the difference in color until it's too late. And it's even harder with Polymax, which is neutral to cold to begin with.
I use selenium 1:9 by the way. When I have used it more dilute and it takes longer and is slower I have an even HARDER time.
A couple of hints to help notice the color change more quickly.
1.) Use tungsten lighting that is not too bright. A 40-watt bulb about 3 feet above your processing tray will be perfect. Block off window light and get rid of any flourescent lighting you might have (it's not natural anyway!). The warmer spectrum of tungsten light will accentuate the color shift to reddish-brown and make small differences easy to see. However, your eye adjusts quickly to such changes therefore...
2.) Keep an untoned print close by under the same lighting conditions to compare to. This will make the assesment of the color change easier.
3.) Decide beforehand just how much color change you want in the image. Toning a print to completion is helpful to see just how much change you can achieve for that paper/toner dilution combination. Then...
4.) Pull the print a bit before the proper tone is reached and transfer it to the wash aid bath. The toning will continue, albeit much more slowly, for up to a minute. Compare this print with your untoned print and see if you like it. If it is too toned, reduce the toning time a bit. (Do keep your timer running while toning and note the time it takes for proper toning for the particular print you are working on. This enables fine-tuning and repeatability. After I have determined a time for one print, I tone thel rest in one batch at that time.)
Also, as Aggie mentioned, I have noticed that the toning seems to lessen somewhat in the wash. This may be a subjective observation however, since the lighting is usually different and there is usually no untoned print for comparison. The color temperature of the light really makes a difference on how much toning is percieved. Tungsen lighting accentuates the tone, sunlight, or even more, skylight (through windows) de-emphasizes it. The same print can look markedly different depending on the light source.
Also, I have found that weaker dilutions result in less overall tone change, even when the prints are toned to completion.
Hope this helps, ;^D)
I would just about totally agree with the advice given by Doremus, the only difference that I have in my approach is that I do not time prints in the toner. Prints being toned in selenium toner respond differently depending on tonality, therefore I believe that the time for a high key print will differ from a very low key print. Low values in the print will begin to change colour before delicate higher values, that is one way to note that the selenium is affecting the image, the blacks will also get slightly darker as the toner starts to work.
Toning is very subjective and needs practice to learn how to control it. If you do happen to give a print too much selenium toning and end up with an unpleasant almost purple print you can recover this by washing and toning in gold. This will cool the mid tones and highlights and bring the lower values back to a more acceptable "plummy" colour. Gold affects highlights and mid tones before lower values which is a useful tool when split toning images.