Sorry Dave i sometimes am guilty of speed reading the forum and i miss things. That's exactly how i do it!
I also don't use reclaimed copper for the process like i do with the stock pots. Only clean copper slabs, but theoretically if you have a copper nitrate solution with contaminants lower than copper in the solution also and you add iron without over doing it to the point of cementing all the copper out then the copper that falls should be of relatively clean purity. At least that's what i've observed. When i take the copper out of my stock pots for using in the upstream stock pots i never wait until the cementing is complete before i draw the first copper off, then the process is completed to finish it off for neutralization. I've never tried it for cementing silver, but i might just do some experimenting to see where it leads me.
I also don't use reclaimed copper for the process like i do with the stock pots. Only clean copper slabs, but theoretically if you have a copper nitrate solution with contaminants lower than copper in the solution also and you add iron without over doing it to the point of cementing all the copper out then the copper that falls should be of relatively clean purity. At least that's what i've observed. When i take the copper out of my stock pots for using in the upstream stock pots i never wait until the cementing is complete before i draw the first copper off, then the process is completed to finish it off for neutralization. I've never tried it for cementing silver, but i might just do some experimenting to see where it leads me.