Why every print goes in the toner
Selenium is usually sold as an archival step. It is that, but the reason every print here goes through it is that it separates the shadows, and the only way to prove it is to keep one print out.
Selenium toner is normally recommended for permanence, and that is true: it converts metallic silver to silver selenide, which is a good deal less interested in the sulphur compounds in the air than silver is. A toned fibre print will outlast an untoned one by a long way, and if that were the only reason it would still be worth six minutes.
It is not the only reason. What selenium actually does to the look of a print is separate the bottom of the scale, and it does it because of where the silver is.
The conversion follows the silver
A print is an image made of silver suspended in gelatin. Where the print is dark there is a lot of silver; where it is light there is very little; where it is paper white there is none at all. When the print goes into the toner, the reaction happens where there is something to react with. So the shadows change and the highlights do not, and it is not a gradient anybody chose. It is the distribution of the material.
The visible result is that the deepest tones pick up a colour, the tones just above them pick up less of it, and the top third of the scale is untouched. Two shadows that read as the same black on the untoned print stop reading as the same black. Nothing has moved on the tone curve; the print does not get darker or lighter. It just stops being one thing at the bottom.
What is fixed here, and does not vary by print
- Selenium at 1:20, six minutes, 20 °C. Never longer for effect.
- Fibre base only. Resin-coated paper takes it differently and the set would stop matching.
- Every print in every series, without exception, including the ones that did not need it.
- One reference print per series, pulled from the wash and kept out of the bath.
The reference print is the point of this note
Six minutes at 1:20 is a mild dilution and a short time. Standing in front of a single toned print you would not necessarily be able to say whether it had been toned at all. You would say it had good separation in the shadows, which is what you would also say about a well-printed untoned frame.
That is exactly why one print from each series never goes in. Same negative, same paper, same grade, same exposure, same developer, same wash. It comes out at the end of the sequence and goes in a box, and when I want to know what the toner did, I put the two on the bench together.
Measured off the two files, a tenth of the tonal scale at a time, the difference is not subtle at the bottom and does not exist at the top:
| Where in the scale | Toned | Untoned |
|---|---|---|
| Deepest tenth | 12.99 | 0.00 |
| Middle | 5.68 | 0.00 |
| Top fifth | 0.05 | 0.00 |
Those figures are the chroma of the print: how far from neutral grey it sits. The untoned print has none anywhere, which is what neutral means. The toned print has a great deal at the bottom and none at the top, which is the whole claim, in three numbers.
A warning about the temptation. It is possible to leave a print in longer and get more. It is also possible to get a print that has clearly been toned, which is a different and worse thing to look at. The bath is a step in a process, not an effect.
What this means if you are printing
Keep a straight print. Not a test strip, not a work print, but a finished print, made properly, from the same session, that you deliberately do not treat. It costs one sheet of paper per series and it is the only way you will ever be able to say what any of your steps are doing rather than what you believe they are doing.
I have wasted years of darkroom time on changes I could not have described afterwards. The one untoned print in the box is the cheapest instrument in the room.
Every print on this site was made this way
Twelve photographs, three sizes, made to order and toned in the same bath for the same six minutes.