bob suggested surrounding the wire with a different form of ptfe, a white tape that was already of uniform thickness. his father expected that the ptfe tape would not stick to the wire, but he tried the idea, and it worked. wires were laid between layers of ptfe tape and sent through a grooved calendar roll, then heated to melt the tape into a coherent coating. the result was a ptfe-insulated ribbon cable containing multiple copper conductors, later called "multi-tet cable".