This sheet of IEC 60371-3 applies to several types of rigid materials based on mica splittings or mica paper for commutator separators. These products shall be made from muscovite or phlogopite mica, built up from mica splittings or mica paper by the use of a suitable bonding medium. They are supplied in the following forms:– sheets in the dimensions in which they are pressed or after trimming;– strips cut from sheets;– commutator separators having the shapes and dimensions and in the conditions ordered by the user.The normal manufacturing thicknesses lie between 0,3 mm and 2 mm.Materials which conform to this specification meet established levels of perfor