Before etching the surface of the gravure/cylinder which is not to be etched is covered with 

The common material used for offset plate graining 

The device that measures the image area percentage at selected area across the printing plate

In screen stencils making by 5-star film method, ----------------- is used as an oxidizing agent.

The process of dissolving unevenly a part of the surface of a metal using an acid or other corrosive substance

The electro deposition of an adherent metallic coating on an electrode for the purpose of securing a surface with properties or dimension different from those of base material