RE: copper prints
This message was sent replying to the message from Dick Sullivan, but I haven't seen that the "reply to" was setted to his personal mailbox:
Several baths of dilute hydrochloric acid 2%.Usually a developer bath is recommended after a copper toning on silver prints to avoid the presence of silver chloride/bromide which may give rise to mirroring especially on the shadows after some time (sometimes after some years...).
As in copper prints there are not silver compounds, I am not sure that a developer bath is an effective cure for stabilizing the print.
Have you any evidence about this? For example, washed in HCl only prints vs. washed and developed prints?