Chasing

Repoussé or repoussage (French pronunciation: [ʁəpuse]; [ʁəpusaʒ] respectively) is a metalworking technique in which a malleable metal is ornamented or shaped by hammering from the reverse side to create a design in low relief. It is a form of toreutics.

There are few techniques that offer such diversity of expression while still being relatively economical. Chasing is the opposite of repoussé, and the two are used in conjunction to create a finished piece. It is also known as embossing.

While repoussé is used to work on the reverse of the metal to form a raised design on the front, chasing is used to refine the design on the front of the work by sinking the metal. The term chasing is derived from the noun "chase", which refers to a groove, furrow, channel, or indentation. The adjectival form is "chased work".

The techniques of repoussé and chasing use the plasticity of metal, forming shapes by degrees. There is no loss of metal in the process as it is stretched locally and the surface remains continuous. The process is relatively slow but a maximum of form is achieved, with one continuous surface of sheet metal of essentially the same thickness. Direct contact of the tools used is usually visible in the result, a condition not always apparent in other techniques, where all evidence of the working method is eliminated.

The word repoussé is French and means "pushed up", ultimately from Latin: pulsare, which means "to push". Repoussage is the noun to refer to the technique, with repoussé being an adjective referring to a piece to which the technique has been applied (e.g. "repoussé work", "repoussé piece"). Chasing comes from the French word, chasser meaning to drive out, or to chase around which is what the artists are doing as they "chase" the forms on their metal in order to create their final design.

...
Wikipedia