In this technique it is necessary to select a suitable interlayer by considering its wettability, flow characteristics, high stability to prevent reactions with the base materials, and the ability to form a composition having a remelt temperature higher than the bonding temperature. The joining technique dates back to ancient times. 
 For example, copper oxide painted as an interlayer and covered with tallow or glue to hold gold balls on to a gold article were heated in a reducing flame to form a eutectic alloy alloy at the bond area.