Toning has been available as a technique since the earliest days of photography, when it was introduced more as a means of trying to permanise the image rather than change it for aesthetic effect. As usually defined, it implies the use of a chemical solution to act on the metallic silver of the image to produce a silver compound of a different colour.
Some toners intensify the density of the image, others may tend to lighten it, and while some can radically improve print permanence, others make the image more ephemeral. Any attempt to map out the action of toners in a ‘unified field theory’ is bound to fail, but that is one of the reasons for using them – every print is a unique piece of art, impossible to repeat exactly.
A prussian-blue dye is produced, as in the cyanotype alternative process. Contrast increases. The full result can be a little intense, but it’s possible to partially tone for more subtle effects. Not regarded as archival, but prints should still last a long time before any fading.
A bit like selenium toning, in the sense that the colour shift is subtle, but with gold it’s towards blue. Also the final print is protected from oxidation so a good permanising treatment. Split toning is possible using gold toner on lith prints.
Selenium toner does different things according to dilution, time in the bath, and the make- up of the paper. In most cases though, at a weak dilution (eg Kodak Selenium Toner at 1+12) expect a ‘cooling off’ and slight shift towards purple. Permanence is improved, and this is regarded as the best archiving treatment.
This is not effective with many papers, but is often possible with the more ‘old fashioned’ warm-tone papers. The idea is that the shadows convert first, and the toning should be stopped before the colour affects the higher tones. The selenium toner should be quite dilute, and using the developer more warm than normal may help.
Copper is never regarded as being as permanent as sepia and selenium, but is as stable as blue, which is fine for normal display.
The print is first bleached, then washed & the image broought back in a toning bath. Partial bleaching will give more subtle sepia tones.
There is a choice, or at least used to be. A sepia toner based on sodium sulphide gives very rich results but the bath has a strong sulphide smell, and there are no commercial packs available now. The odourless alternative is Thiourea & has the advantage that the chemistry can be adjusted to control the colour.
Sepia + Copper
A way of raising the intensity levels, partial sepia followed by copper.
Sepia + Blue
Multiple toning can take you into interesting areas. By combining partial sepia, followed by blue a good subtle green can be achieved, while still keeping a good maximum black.
All prints courtesy of Mike Crawford, Lighthouse Darkroom