Caulking irons are used to fill the gaps between the boards that make up the hull or deck of the barquettes marseillaises. They exist in several variations and can either be cutting irons used to rectify the outer planks and equalize the interstice or working irons intended to force the tow into the interstices. The irons must be held in such a way as not to expose the fingers to the blows of the mallet used to drive them in.