3,3′-Thiodipropanoic acid S(CH₂CH₂COOH)₂

Used in the Ligand solution for the Chrysotype printing process.

The New Chrysotype process has tonal and surface qualities and permanence like Platino-palladiotype, but a bonus feature of beautiful muted colours controlled by the chemistry of the process. Photographic artists should discover here a whole new palette of non-literal colour to explore in printing archivally permanent ‘monochrome’ images in hand-coated noble metal sensitizers:

http://www.mikeware.co.uk/mikeware/New_Chrysotype_Process.html