Keep non-sparking tools clean and free of ferrous metal contamination which can reduce their non-sparking ability. Avoid contact with acetylene which can form explosive acetylides, especially in the presence of moisture. If damage has occurred to the striking face of hammers or to the edge of chisels, the tools should have the faces and heads redressed. Do not store hammers and other hand tools fitted with wooden handles in places where the handles may dry out and shrink. This will increase the risk of the handle breaking or the head becoming loose.