Sixty years after the first measurement of capillary properties of silicon, experimental results on the surface tension and temperature coefficient of liquid silicon are still divergent. The reason for this persisting divergence is discussed by examining the effect on these quantities of (i) oxygen contained as an impurity in the gas, (ii) impurities in Si and (iii) contamination by the supporting material (substrate or crucible). From the analysis of experimental data, the following expression is derived for the temperature dependence of the surface tension sigma: sigma-(mN/m) = 840(+/- 45) 0.19(+/- 0.09)(T(K) - 1685). (C) 2013 Elsevier B.V. All rights reserved.