A surface treatment device includes an enclosure which has an opening through which the leading edge of an aerofoil passes. A sealing element is provided on the enclosure to seal the device to the surfaces of the aerofoil. An abrasive is located within the enclosure and two fluid openings are also provided through which a chemical accelerant can be pumped. In operation the enclosure is oscillated relative to the component so that material is abraded. Whilst the enclosure is oscillated a chemical accelerant is simultaneously pumped through it. The device allows for the local application of a surface treatment on a component.