Besides the large class of ferrocyanide toners, which can be used for creating brightly colored prints, there also is a class of toners, based on sulfide. These toners can be used to create images with colors ranging from sepia to chocolate brown and purplish/brown. The basis of these toners are sulfide ions.
Plain sulfide toning
This is probably the best known toner in photography. It is almost fool-proof, easy to prepare and does not suffer from staining, when applied properly. This toner exists in two variations:
Both of these toners require a pre-bleach step with ferricyanide and bromide, which replaces the silver image by a mix of silver bromide and some silver ferrocyanide. The bleached silver then is converted to brown silver sulfide by immersion in a sulfiding bath. There are numerous recipes for such sulfide toners. Some recipes, together with instructions on usage and safety, are given here: http://www.jackspcs.com/toner.htm.
Polysulfide toning can be used as a single bath toner for converting a black silver image to a deep brown silver sulfide image. The resulting color of such a toned print is deeper than the color of a sepia-toned print with sulfide. For many purposes, the polysulfide-toned print is more attractive than a plain sulfide-toned print. From an archival point of view, a polysulfide-toned print is almost as good as a sulfide-toned print.
A polysulfide toner, however, requires the use of a polysulfide compound, such as sodium polysulfide or potassium polysulfide, also known as liver of sulphur. Liver of sulphur is quite expensive and harder to obtain than plain sulfide. Fortunately, a suitable alternative can be made easily at home from other cheaper chemicals. From a chemical point of view, the procedure outlined below is nothing new, but for photographers, this procedure may be quite unknown.
In order to make a polysulfide toner, normal sulfide and elementary sulphur are needed. The relative ease of the reaction, in which sulphur is combined with sulfide is exploited here. The reaction is as follows (1 ≤ n ≤ 4):
S2- + n S → S1+n2- (in words: sulfide + sulphur → polysulfide)
Preparation of the polysulfide solution can be done as follows:
The process can be scaled up easily for making more toner liquid. The toner must be fairly warm, when it is used, otherwise it works very slowly. This toner is a derivation of http://www.jackspcs.com/pst.htm, and directions of use from that recipe can be applied here as well. The toner solution can be stored for a long time and is quite stable.