A method and apparatus to hermetically seal openings in an explosion suppression chamber. The orbiting scroll is set up on a drive shaft so as to be able to orbit. A colour change of said thermochromic fibres is induced during one step of the manufacturing process and the presence of the thermochromic fibres being in their contrasting state is detected by a detection means. A pinned stack is formed adjacent to the first side of the tunneling barrier layer. The faceplate may be decorative, and interchangeable, for prominent display in front of the necktie.