APPLICATIONS PRINTING IN BLACK & WHITE TONING PRINTS
Sepia toning converts the silver image to tones ranging from light to dark brown.
Such toning can be achieved by using either Direct or Indirect toners.
Sepia toning requires the image to be bleached before toning. Both lead to an improved image permanence.
Below gives details on ‘Direct’ and ‘Indirect’ techniques - for sepia toning images.
Direct Sulphide toners
Direct Sulphide toners are single solution toners, and act on the image directly - to convert it (partially or completely) to silver sulphide.
Direct sulphide toners work well with ILFORD MULTIGRADE FB WARMTONE paper. Such toners have little effect on MULTIGRADE IV papers however.
These types of toners have the advantage that toning can be stopped when the desired colour is reached, and also partially toned images can be further treated in other toners to produce various other special effects.
Prints toned in direct sulphide toners generally have similar density and contrast - to untoned prints.
These toners can be used at room temperature but they act very slowly - taking up to 30 minutes to reach completion. This time can be shortened considerably by raising the temperature to 100F/38C, but the drawback is that at higher temperatures this already initially strong smelling toning solution - will be even more unpleasant.
Examples of commercially available direct sulphide toners are :- Kodak Brown toner, Photographers Formulary Hypo-alum, and Photographers Formulary Polysulfide.
Indirect Sulphide toners
Indirect toners use a two step technique - involving bleaching and then redeveloping the image in order to convert the silver image. This can be either a partial or complete conversion - to brown silver sulphide.
Sulphide sepia toners and non-variable warmth thiourea toners work well with MULTIGRADE papers, but give a rather cold brown image colour on MULTIGRADE IV papers.
Prints toned in sepia toner can be further toned in blue (iron) toner to give a green tone - or, if only partially bleached, a blue/green/sepia split tone.
They can also be treated in a gold toner to produce an orange-red image.
The bleach used is normally a ferricyanide bromide type - which converts the silver image to silver bromide.
The darkening (redeveloping) solution can be a solution of sodium sulphide. However this solution has a very strong/nasty smell - and most users now prefer to use odourless toners.
Odourless toners use an alkaline solution of thiourea to convert the silver bromide image to silver sulphide.
Apart from being odourless, they also have the advantage of allowing the resulting image colour to be adjusted by controlling the pH of the second bath.
The pH adjustment is achieved by adding more or less sodium hydroxide solution to the second bath. More additive gives a colder image tone, less additive gives a warmer image tone.
Prints toned to have a very warm image tone generally have considerably lower density and contrast to untoned prints.
Examples of commercially available indirect sulphide toners are :-
- Indirect sulphide toners - Berg Rapid RC Sepia, Kodak Sepia, Photographers Formulary Sepia Sulphide 221, and Tetenal Sulphide.
- Thiourea sulphide toners (non variable warmth) - Photographers Formulary Thiourea, Speedibrews Speedisepia.
- Thiourea sulphide toners (variable warmth) - Fotospeed ST20 sepia toner, Rayco Varisepia, Tetenal Triponal.