ABSTRACT
The best information available since K. B. Hendriks death in 1997 suggests that toning, following the protocols established by the Image Permanence Institute, should be performed on all silver photographic materials new or old. Proprietary toners where the contents are approximately but not exactly known Sistan was a stabilizer originally intended to protect RC prints. It was formulated by Agfa and later made by a successor company, Adox. It was claimed to work equally well with fiber base prints and negatives to protect the silver in the image. Ag-Guard was a product introduced in 1984 by Fuji. Fuji stated it contained a ‘very stable sulfur compound’ which Material Safety Data Sheet research revealed to be 2-ethanesulfonic acid, CAS 25985–57–3, at 0.5 to 1.5%, in water. All the aspects will ensure that the optimum equilibrium among polysulfides is present in solution, thus controlling the toning reaction kinetics.
