A method of direct casting crystalline metal sheet in continuous strip form from a melt of metal having a melting point below about 900.degree. C. on a continuously driven substantially smooth chill surface cooled to extract heat from the strip being cast avoids gas pockets between the strip and chill surface by applying heat from an external source to the chill surface prior to the chill reentering the melt whereby vaporizable condensates and deposits on the chill surface are eliminated prior to contact with the melt.