Methods and apparatus for isotropically etching a metal from a work piece, while recovering and reconstituting the chemical etchant are described. Various embodiments include apparatus and methods for etching where the recovered and reconstituted etchant is reused in a continuous loop recirculation scheme. Steady state conditions can be achieved where these processes are repeated over and over with occasional bleed and feed to replenish reagents and/or adjust parameters such as pH, ionic strength, salinity and the like.