The use of ceramic-to-metal seals and joints has assumed increased importance in todays technology.Historically, the joining of ceramics to metals came of age as an industrial process during World War II in Germany where, under wartime conditions, it was recognized, that electronic vacuum tubes with increased reliability and longer performance could be produced by substituting ceramic materials for glass.Pulfrich and Vatter established procedures to metallize ceramics, thus producing surfaces that could be readily wet by brazing filler metals.Some of the most significant of the many domestic and foreign patents assigned to Pulfrich, Vatter, and the firms that employed them are listed among the references.While the results obtained by these early workers appear somewhat crude in the light of current developments, the basic concepts of metallizing are still valid and these procedures, or modifications thereof, are in current use to prepare ceramic surfaces for joining.