A critical investigation of the use of the wetting balance to characterize leadfinish solderability is described. The wetting force vs. time curves for matte tin and solder plated copper coupons which have been subjected to well controlled environmental conditions, such as steam and high temperature bakes have been analyzed. Steam exposure was shown to impact greatly the shape of the wetting force curve, with the major effect observed after one hour of exposure and with no significant changes upon further exposure. The high temperature exposure (bake) and associated intermetallic compound formation had little effect on the force-time curve as long as it was protected from oxidation. Results show that when the wetting balance is used in conjunction with SEM and microanalysis tools, it is an excellent diagnostic tool for determining sources of solderability changes.