Method for preserving a mark on a metallic workpiece

22:

• The method according to claim 1, wherein the mark on the metallic workpiece comprises an etch or anneal mark and the chemical process is a chemical etching process.

23:

• The method according to claim 1, wherein the step of deepening the mark relative to the metallic surface of the workpiece to form the first depth comprises reacting a surface of the mark with an acidic solution.

24:

• The method according to claim 1, wherein the metallic filling material is a different metallic material to that of the workpiece.

25:

• The method according to claim 1, wherein the step of depositing the metallic filling material comprises an electrochemical reaction in the presence of a metal ion-containing electrolyte solution at the first depth of the mark.

26:

• The method according to claim 1, wherein the chemical
• l process comprises etching with an alkaline solution.

27:

• The method according to claim 1, wherein the surface of the workpiece is anodized.

28:

• The method according to claim 1, wherein the chemical process comprises removing at least an oxide layer from the surface of the workpiece.

29:

• The method according to claim 1, further comprising a step of treating the surface of the workpiece carrying the mark prior to the step of deepening the mark to form a first depth.

30:

• The method according to claim 9, wherein the treating step comprises removing at least a surface oxide layer from the mark.

31:

• The method according to claim 10, wherein the treating step is applied to at least a portion of the surface of the work piece surrounding the mark, but is such that it does not remove all of the surface material from said portion of the surface of the workpiece, but removes at least the surface oxide layer from the mark.

32:

• The method according to claim 11, wherein the treating step comprises laser treatment of the portion of the surface.

33:

• The method according to claim 12, wherein the power of the laser is set such that it does not remove all of the surface material from said portion of the surface of the workpiece, but removes at least the surface oxide layer from the mark.

34:

• The method according to claim 1, wherein the steps of deepening the mark relative to the metallic surface of the workpiece to form a first depth and depositing the metallic filling material into the first depth is conducted simultaneously under an electrochemical reaction between an acidic, metal ion-containing electrolyte solution and a material at the mark.

35:

• The method according to claim 14, wherein the metallic material at the mark is dissolved by the acidic electrolyte solution to generate the first depth whilst depositing the metallic filing material into the first depth.

37:

• The method according to claim 16, wherein the treating step comprises laser treatment of the surface.

38:

• The method according to claim 16, wherein the treating step being arranged such that it does not remove all surface material from said surface of the workpiece, but removes at least the surface oxide layer from the etch mark.

39:

• The method according to claim 16, wherein the reacting step and the depositing step comprise an electrochemical reaction between an acidic, metal ion-containing electrolyte solution and a material at the etch mark.