RE: Sweets Copper Remover
The use of ammonia-based solvents has been debated a LOT, but from what I' ve heard & read.................the ammonia by itself will do NOTHING to the steel. What it does do is act as a moisture attractant and catalyst that promotes rust in the steel that the trapped moisture contacts.
If this is true, then all one has to do is remove the moisture along with the ammonia and all should be well. This is why after using Sweets or CR-10, I run a few more patches of a standard solvent, followed by a couple of dry patches, and finally by a patch or 2 of denatured alcohol - this should remove the last trace of water moisture as the alcohol evaporates. Follow with a good oil patch and there should be no problem.
At least this has worked for me over the years.