Ok , that makes sense now. I wasn’t submerging the part, just swabbing it with a Q-tip. Your scenario is similar to the old cathodic rust removal with a battery charger trick, I get it now. I don’t know how fine of a grit I have been polishing with. I sanded down with a flapper wheel then went to a brown Scotchbrite disc and finally finished with a blue Scotchbrite disk. It is not a mirror finish. I will get some polishing disks ordered. I also ordered some of this
https://etchantstore.com/product/stainless-steel-weld-etch-250-ml/ Stainless Steel Weld Etch online, I’ll give it a try when it arrives.
Lawrence, I have also had luck with warming the part some when using ammonium persulfate on carbon steels. I have had just the opposite experience with the nitric acid though, I seem to get better results if the coupon is dead cold. I run cold water over it for in the sink a few minutes and it seems to have a better definition.
Thank you for your help guys!