CORROSION MYSTERY WITH CADMIUM PLATING

ONE of the more interesting corrosion problems investigated during the current year occurred at a manufactory of electronic equipment. Located in the north of England, this company specialised in the production of audio frequency amplifiers of a very high quality, and the management were disturbed, over a period of five years, by sporadic complaints of corrosion on a small proportion of their chassis units. It took the form of dark grey or black patches, up to about 2 sq.in. in area, which did not develop until the units had been built into specially made wooden cabinets at a sub‐contractor's premises. An interval of several months could pass between manufacture and installation, and units inspected after storage and immediately prior to dispatch to the sub‐contractor were subsequently returned in the condition described.