Cathode mask knob

The device for holding the center portion of a record matrix in liquid-tight electrical contact with a threaded end of a cathode of an electroforming apparatus;

• said device being an integral member comprised of a metal insert, a dielectric shield and a resilient seal;
• said metal insert having an exposed threaded end portion shaped to threadably engage and mate with the threaded end of the cathode;
• said metal insert being mounted in said dielectric shield with said shield electrically insulating all the surfaces of the metal insert with the exception of the exposed end portion and said resilient seal being positioned in said shield adjacent to and surrounding the metal insert whereby when a matrix is placed on the surface of said cathode and said device is threaded with and tightened onto said cathode, the metal insert forces the matrix into electrical contact with the cathode;
• the seal member compresses to form a liquid-tight seal about the metal insert and the dielectric shield prevents plating of the metal insert.