Chemical milling or
industrial etching is the
subtractive manufacturing process of using baths of temperature-regulated etching chemicals to remove material to create an object with the desired shape. It is mostly used on metals, though other materials are increasingly important. It was developed from armor-decorating and printing
etching processes developed during the
Renaissance as alternatives to
engraving on metal. The process essentially involves bathing the cutting areas in a corrosive chemical known as an
etchant, which reacts with the material in the area to be cut and causes the solid material to be dissolved; inert substances known as
maskants are used to etch specific areas of the material.