An experimental investigation of steady-state natural convection from vertical rectangular mild steel and aluminum fins was conducted using laser holographic interferometry. Infinite-fringe interferograms demonstrate the effect of fin base heating. Depending on the fin material and base temperature, the local heat transfer Coefficients vary along the fin with maximum values at positions about 22-48% of the fin height measured from the base. Temperature measurements along the fin show good agreement with the classical one-dimensional convective and adiabatic tip solutions. Hence, in the thermal design of vertical aluminum fins of low Blot numbers, the classical one-dimensional fin solutions may be used together with on average heat transfer coefficient obtained from established correlations for natural convection from an isothermal flat plate.