If somebody put them there then the chemical process already started. End of roll toning I thought was only from OBW. Maybe not
Toning starts with oxidation... reaction of the metals to the gases in the air around it or agents on/nearby the piece... before anyone put anything anywhere, the 'air' is all around and all the time working it's magic.
Dimefreak: Sometime back on CT, Paul (Lehigh96), shared this CU link to threads by Sonnywood on his coin toning classification system. It's a very interesting read. A Color Chart for the Thin Film Color Progression