Assemblies and methods for anodizing a workpiece selectively using a combination of a mechanical mask and a gas bubble or air pocket mask

An apparatus for use in anodizing a metal workpiece, the apparatus comprising:

• a) an upper support member;
• b) a mechanical mask provided between the upper support member and the metal workpiece to block electrolyte from at least one surface area of the metal workpiece;
• c) the metal workpiece having a cavity;
• d) a gas trapped in at least a part of the cavity in the metal workpiece and blocking electrolyte from at least one surface area of the cavity;
• e) an anode contacting at least a part of the metal workpiece;
• f) a lower support member supporting at least a portion of the anode;
• and
• g) a reservoir of electrolyte including a cathode, wherein the metal workpiece is held in the reservoir of electrolyte in an orientation such that gas trapped in at least a part of the cavity in the metal workpiece will block the electrolyte from at least one surface area of the cavity,
• wherein the anode covers an opening of the cavity in the metal workpiece.

An anodizing process comprising:

• a) clamping a metal workpiece having a cavity in a holder, the holder including
• 1) an upper support member,
• 2) a mechanical mask provided between the upper support member and the metal workpiece to block electrolyte from at least one surface area of the metal workpiece,
• 3) an anode contacting at least a part of the metal workpiece, and
• 4) a lower support member supporting at least a portion of the anode;
• b) lowering the holder with the metal workpiece clamped into a reservoir of electrolyte, having at least one cathode, in an orientation such that gas trapped in at least a part of the cavity in the metal workpiece will block the electrolyte from at least one surface area of the cavity;
• and
• c) anodizing the metal workpiece using a power supply to apply a voltage across the cathode and the anode, to generate a selectively anodized metal workpiece.