The etching step is preferably followed by {HEAD ~ a polishing step} which comprises providing a thin film of a second acidic aqueous etchant solution containing an alkaline earth salt; then contacting said electrode tip to the thin film: and then etching {TAIL ~ the tip} at about 2 volts rms ac to thereby polish the tip 
comprises etching
The etching step is preferably followed by { HEAD ~ a polishing step } which comprises providing a thin film of a second acidic aqueous etchant solution containing an alkaline earth salt ; then contacting said electrode tip to the thin film : and then etching { TAIL ~ the tip } at about 2 volts rms ac to thereby polish the tip
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH