As a result of drying, hammer heads often become loose in the wooden handle of the hammer. One method that has proven successful in tightening the head on a handle is to soak the hammer head and handle in a container of linseed oil.
The container may be a tin can large enough in diameter to take the head of the hammer and at least 2" deep. Place the hammer head and wooden handle in the container and pour in sufficient linseed oil to cover the handle slightly above the eye of the hammer head. Allow the handle to soak at least 24 hours, then remove the hammer from the oil and wipe the head clean. It is advisable to tighten the wedges by driving them in deeper.