Removing Tungsten Trioxide from Tungsten Electrode

I need a very sharp tungsten electrode, and I think radial electrochemical etching with sodium hydroxide is the way to go. The problem therein (I think) is that the etching will cause an oxide layer to form deeper than the native oxide layer, ruining the electrode.

Are there any reactions close to STP that will get rid of a few layers of $\ce{WO3}$? I found one recommendation that involves using ammonia as a reducing agent at 80 °C, but I can't determine its validity.

$$\ce{WO3 + 2 NH3 -> 3 H2O + W + N2}$$

• Welcome to Chemistry.SE! Take the tour to get familiar with this site. Could you link back to that recommendation to see the context? – Martin - マーチン Nov 27 '17 at 7:04