Dassonville T-56 Bleach and Redevelop Selenium Toner produces rich purple to deep brown with longer treatment time. This toner works with most papers including cold-tone that show minimal color shift in monobath toners.

CHEMICAL SAFETY

SELENIUM is highly poisonous in both powder and vapor forms. Mix and use in a well ventilated room with an appropriate fume mask and gloves.

SODIUM SULFIDE is not Sodium Sulfite. Sodium Sulfite, a preservative used in almost all photographic developers, is considered to be a bland chemical. Sodium Sulfide is a powerful fogging agent, is used mainly in toning bath and is a dangerous chemical if used incorrectly. Sodium Sulfide should be used with considerable care. Do not allow it to come into contact with acidic solutions. Sodium Sulfide (as a solid or in solutions will react with acid to form hydrogen sulfide, a foul smelling and poisonous gas. Hydrogen sulfide gas will fog photographic emulsions so keep paper and film isolated when toning. Sodium Sulfide and its solutions are caustic. Do not allow them to come into contact with the skin as they can cause a chemical burn. If contact should occur, wash the area first with cold water followed by soap and water. Dispose of solid Sodium Sulfide or a solution of Sodium Sulfide down a drain. First run cold tap water down the drain for a few minutes to make sure no acid remains in the drain trap, place the solid or pour the liquid into the drain. Run tap water down the drain for at least 5 minutes.

POTASSIUM FERRICYANIDE: In spite of the fact that this compound contains cyanide, it is not particularly toxic. The reason is that the cyanide groups bind to the iron atom and are not free to act as a poison. The cyanide groups can be released as hydrogen cyanide gas if the Potassium Ferricyanide is placed in a strong acid solution. Dispose of excess Potassium Ferricyanide down the drain with excessive amounts of water.

MIXING THE SOLUTIONS

CAUTION: Never use metal utensils or containers in the preparation of or in the use of toning solutions.

BLEACH SOLUTION

Chemical	Amount	Units
Water	750	ml
Potassium Ferricynide	100	g
Potassium Bromide	100	g
water to make	1000	ml

TONING STOCK SOLUTION

Chemical	Amount	Units
Water	100	ml
Sodium Sulfide	25	g
Selenium powder	5	g

Dissolve the Sodium Sulfide and warm the solution before adding the Selenium powder. Heat until the Selenium powder is completely dissolved.

USAGE
Dilute the stock toning solution 1:20 with water. Immerse the bleached print in the working solution for 3 to 5 minutes with continuous agitation. Wash the toned print thoughly. The working solution deteriorates rapidly, discard the working solution after use.

REFERENCE
Print Toners, Dassonville T-56 Bleach and Redevelop Selenium Toner
The Photographer's Master Printing Course, Tim Rudman, p.121, 151.
The Photographer's Toning Book, Tim Rudman, p.49, 182.
The Darkroom Cookbook (2nd Edition), Stephen G. Anchell, p.233.