[en] Using the methods of measurement of capillary force of the investigated electrode, which is being drawn into melt, electrocapillary curves (ECC) are obtained of iron and its alloy with 1.54 wt% of C in liquid sodium tetraborate at 900 deg C. The given methods allow to fix during one experiment a variation in interphase tension, the angle of electrode wetting by melt and surface tension of electrolyte at boundary polarization. According to the values of interphase tension and wetting angle, the melt adhesion to solid metal is calculated at different electrode potentials. An equation which describes ECC with a minimum is suggested. The minimum on ECC can be accounted for by boron adsorption on the electrode