Viradon

Viradon is a brown toner made by AGFA. It is a brown to pink toner, which can also be used as a treatment for the archival of negatives and prints.

The toning action is based on the reaction of Sodium or Potassium polysulfide (Na2Sx) and Selenium on the Silver on prints or negatives which will turn dark brown without the need for bleaching. The resulting tone depends on the paper that is applied, with warm tone papers being affected the most. It is also noteworthy that this toner keeps acting in the washing, giving peach colored highlights, and thus the use of a hypo-clearing (10% Na-Sulphite) is highly recommended.

This toner is good for image permanence, as the resulting colored compounds are very stable, thus the archival characteristics of the prints, especially when mixed with selenium. In the words of Rickard Knoppow "Because Polysulfide toners affect all densities equally they provide good protection to an image even when only partially toned. The current recommended toner for protecting microfilm is a Polysulfide toner. I don't know the life of the mixed toner."

The original Viradon was introduced in the 1930s and contained both polysulphides and selenium and was used at dilutions of 1+50 and was similar to the original Kodak Poly-toner. The formula of Viradon was modified in the year 2000 to comply with environmental regulations, becoming a brown poly-sulphide toner used in dilutions around 1+25 similar to Kodak's brown toner. It could be mixed with Selenium toner to obtain results similars to the old Viradon.

The production and sale of Viradon was discontinued in 2012.

References

• Rudman, Tim. 2002. The photographer's toning book. Argentum.
• Richard Knoppow - Discussion in pure-silver mailing list