Pipe residues are the small pieces of material that remain in a pipe after it has been used. The two most common types of pipe residues are dottles and dottels. Dottles are the small pieces of tobacco that remain in a pipe after smoking, while dottels are the small pieces of material that remain in a pipe after it has been used for other purposes. Both dottles and dottels can be difficult to remove from a pipe and can cause blockages if not properly cleaned out.