Sheffield Lab Matrix

Do not confuse with Sheffield Lab American plating corporation incorporated Sept 17, 1979 as an outgrowth of Sheffield Lab Records. After plating for WEA labels on an independent basis, It was bought by WEA Manufacturing on December 22, 1980. Founder Doug Sax was retained as quality control consultant and so was the lab's chief technician, Richard Doss, as general manager. Please use the 'Mastered At' Label/Company credit for the time being, as instructed here. Manufactured the metal parts used to press records: the Master/Matrix/Father discs, the Metal Mother discs and the Stamper discs. Usually denoted by "SLM △ 00000" / "SLM △ 00000-X" etchings in the matrix/runout area or sometimes just "△ 00000" / "△ 00000-X", and optionally with a "-SH#" in (at the end of) the matrix number string (# being a number). △ 00000 is a unique SLM number and can be added as LCCN number (see here for an example).