It has been found that High Intensity Conditioning (HIC) significantly increases the flotation rare of pentlandite from a nickel ore. A systematic investigation of slime surface coatings and the effect of HIC on surface cleaning of the nickel ore was carried out using Scanning Electron Microscopy (SEM), Image Analysis, X-ray Diffraction (XRD), and a sieving technique. The sieving technique was established to semi-quantitatively determine the state of slime (< 3 to 5 mu m) surface coatings using a combination of sieving and laser diffraction particle size analysis. If was found that hydrophilic gangue slimes were present on both pentlandite and gangue mineral surfaces prior to HIC. The surface coating by the slime mineral particles was apparently non-selective towards any particular mineral. High Intensify Conditioning removed slimes from the mineral particle surfaces, the amount removed depending upon both agitation intensity and time.