Potato cv. Bintje tubers (50-60 mm grade) from plants grown with a low or high rate of K fertilizer and stored for 3, 5 or 7 months were impacted at 3 different rate by 3 different shaped impact bodies using a computer-controlled pendulum. A spherical impact body doubled the volume and depth of discoloured tissue relative to a non-spherical impact body. The differences in volume and depth of discoloured tissue after impact with 2 different spherical impact bodies (radii of curvature 30 or 15 mm) was minimal. Reducing the impact energy from 0.600 to 0.067 J yielded an average reduction of the volume of discoloured tissue of about 95% and an average reduction of the depth of discoloured tissue of about 80%. Susceptibility to discoloration was greater with low K fertilizer and was greatest with storage for 5 months.