Chemical etching is a multistage photo-lithographic process. The metal is first cleaned and then laminated with a UV sensitive photoresist film. A photo tool containing the desired artwork is placed on top of the laminated material. It is then exposed to UV light.
The UV light passes through the clear areas of the photo tool hardening the laminated film. The sheet is then chemically developed to wash away the unexposed photoresist leaving a very precise mask of hardened photoresist behind.
The material is placed in the etching machine where is it sprayed with a high pressure temperature regulated chemical spray (most commonly Ferric Chloride). The solution etches away the unprotected portions of the material to reproduce the desired image.
The chemical spray dissolves the material atom by atom for a smooth burr free finish. In the final stage the photoresist is stripped away leaving the material ready for any post etching processes required.