Probably the most useful of all types of toner, and has a variety of effects, depending on paper type and dilution. The image will be intensified, extending the tonal range, while also being protected against atmospheric oxidation. Changes in image colour depend on the type of paper being used, chloro-bromide papers being affected the most, bromide papers the least. With chloro-bromide papers the shift is towards a heavy purple-brown. Other papers with a lower chloride content, such as Bromofort, will tend to give a more pure purple colour as well as exhibiting an intensifying effect. ‘Split-toning’ is possible with chloro-bromide papers – the deepest shadows alter in colour while higher tones are unchanged. Resin coated papers will show little visible change, but the treatment is still recommended for maximum permanence. Selenium toner is a single bath which does not use bleaching. Hypo-Clearing Agent is therefore recommended. Dilution is between 1+3 and 1+20 depending upon paper type and effect required. Selenium toner is toxic, so good ventilation and gloves are mandatory. Kodak have produced a selenium toner for many decades
A decade or two ago Ilford stated toning was not their area, but they have now entered the market with a selenium toner – and justly so, as they supply everything else required for high quality printing.
Fotospeed produce a single solution selenium toner, that has generally similar properties to the Kodak product, but being slower is regarded as more controllable in some applications. Dilution range from 1+3 to 1+12.