DC removes metal but creates a lot of gassing. DC etch for just a few seconds then get off for just as long. Do it again 5-15 times or so to get the depth you want. Then turn to AC. AC is Alternating Current so every 60 seconds the current changes. It removes metal and puts it back on, then does it again and again, 60 times a second.
One you have your etch, put the blade in boiling water with TSP in it. Let it boil for a minute or two and then dry it off and let it set. This seems to set the oxides.
Then a very light buff, no pressure, will clean up any halo but if you put pressure on it you will reach in and remove oxides.
I use a full pad on the etcher/anodizer machine I built.
After use I clean the stencils in running water and dish soap, dry in a folded paper towel then put inside another paper towel and place inside a small metal breath mint box to store.