Apparatus for electrolytic etching

In apparatus for electrolytically etching a precision groove pattern in a metal workpiece using a vessel, an electrode and means for applying alternating electric potential between the electrode and the workpiece, the improvement comprising:

• a shield of non-conductive material, capable of being interposed between the workpiece and the electrode, having:
• a horizontally disposed base plate containing an aperture, the aperture having small dimensions compared to the base plate and the workpiece,
• a concave shape of sufficient dimension to contain the electrode, the shape being adapted to divert passage toward the electrode of gases generated at the workpiece,
• a shape which allows circulation of electrolyte through the aperture, to avoid stagnation and heating of electrolyte contained within the concavity of the shield,
• means for fixedly holding the shield between the electrode and the workpiece, and means for holding the electrode within the shield concavity, so that a current distribution is achieved at the workpiece which promotes uniformity of depth of etching.