[kevs]

Well if Sistan isn't wiped off properly it may leave yellow brown staining. Let some of it dry in a tray and you should get yellow marks as far as I know. I only tone my prints lightly so to make sure they are Archival I use Sistan.

Not sure if you're aware, but Sistan isn't needed if you're using polysulphide toner; it gives archival benefits regardless of depth of colour change. See http://www.silverprint.co.uk/plus_ar...ID=11&TextID=6 for an interesting piece from Silverprint.

Cheers,
kevs