Oakum is a type of rope made of tarred fibre. It is normally used to fill gaps. The main traditional use of oakum was in shipbuilding. It was used for caulking, It was used to fill areas between timbers in wooden vessels and the deck planking of iron and steel ships. Oakum was also used in plumbing to seal connections in cast iron pipe and in log cabins for chinking. In ship caulking, it was put into the seams using a hammer and a caulking iron, then sealed into place with hot pitch.