Editing Repoussé and chasing (section)

== Methods ==
[[Image:Maurice Ascalon 2.jpg|thumb|Sculptor [[Maurice Ascalon]] at work undertaking the finishing chasing of a copper repoussé relief sculpture circa 1939.]]

The process of chasing and repoussé requires a number of steps.

===Annealing===
The metal plate should usually be [[annealing (metallurgy)|annealed]]—that is, heated for some time at a temperature sufficient to [[recovery (metallurgy)|reduce its internal stresses]]—to make it as [[malleability|malleable]] as possible.  This process may have to be repeated several times, as many metals [[work hardening|harden]] and become brittle as they are deformed by the hammering.

===Pitch backing===
The plate must then be fixed on a suitable support.  A commonly used technique is to place the metal over a layer of [[chasers pitch]].  The pitch is heated until it is soft enough to make good contact with the metal, filling all its nooks and crannies, and then allowed to cool.  At room temperature, the pitch must be hard enough to adhere to the metal and hold it in place, but still soft and [[plasticity (physics)|plastic]] enough to "give" as the metal is hammered into it.

The pitch is often cast as a thick layer over some softer backing material that can absorb larger deformations.

The metal plate will have to be released from the pitch several times, for turning it over and/or for re-annealing.  Pitch residues stuck to the plate must be removed with an appropriate [[solvent]].

===Lining===
Once the plate is firmly held by the pitch, front side up, the outline of the desired design is lightly chased ("lined") on it by a special tool (a "liner"), that creates narrow raised lines on the other side.

===Repoussé and chasing===
The metal is turned over, and firmed again over the pitch, with the back side up. The main repoussé work is then performed, using a variety of punches.

Once the main repoussé is done, the piece is again released by heating.  The cavities on the back side, created by the repoussé  work, are filled with melted pitch.  Once that filling has hardened, the plate is again turned over and placed on top of a layer of softened pitch.  Once the pitch has hardened, the design is then refined by chasing.  These procedures can be repeated several times, alternating between repoussé and chasing.

===Hot forming===
Repoussé and chasing can also be done on materials, like [[steel]], that are too hard to be cold-formed by hammering.  That is accomplished by heating the piece to a high enough temperature to make it malleable, as in [[forging]].  In this case pitch must be dispensed with, or replaced by some material (like sand) that can withstand the heat and provide the right kind of "giving" support.