Stainless steel etching

Farny aimed to etch stainless steel to produce cathode and anode parts.

He used a mixture of hydrochloric acid (HCl), water (H₂O), and hydrogen peroxide (H₂O₂).

The peroxide acts as a catalysator, so when the solution stops etching, add a few mls of it and start again (as long as there is still some HCl in it).

In the first 10 seconds after submerging the steel sheet into the etching solution nothing happens, then rapid reaction begins.

Farny lists a 3:1 ratio of H₂O:HCl and gradually added H₂O₂.

He also tried to apply a photoresistive layer on the clean sheet.

Farny planned to use stainless steel foil (316 type) with a thickness of 0.1mm.