The dependence of the degree of supercooling(&Dgr;T−)of melts preceding the onset of solidification on the level of melt overheating(&Dgr;T+)above the equilibrium liquidus or melting temperature, is investigated on Sn and SnPb. We demonstrate the dependence of&Dgr;T−on&Dgr;T+can be either abrupt or continuous, depending on the length of holding time. In particular, the dependence is bounded by two discontinuous limits, and the known continuous linear relationship between&Dgr;T−and&Dgr;T+is only a special possibility. Our observations can be tentatively linked to the transient structural evolution of melts, and are probably general, occurring also for element Bi and SnSb. Our results may have important consequences for any thermal modeling of electronics manufacturing involving soldering operations. ©1997 American Institute of Physics.