Caulking

Caulking (also: Kalfaten, arab kafr "Asphalt " and Kalafa. ) Is an activity in shipbuilding, in which the seams between wooden planks with oakum or cotton and wood tar, pitch or rubber are sealed.

The tow or cotton is struck with Kalfateisen constrained using a Kalfathammers in the seams before they are sealed with pitch or with a special rubber compound.

Tools

The Kalfathammer has a wooden cylindrical head with a diameter of about six inches and a length of approximately 20 to 30 centimeters. To protect against splintering it is provided with a plurality of rings of steel. The best wood for the head is lignum vitae, as it is very hard and heavy and not easily splinter. Since it is difficult to obtain, other hardwoods are used. More recently, plastic hammers are offered. The stem is like other tool handles well, usually made ​​of ash. At one end it is slightly thickened, the hammer head is a matching tapered bore. If the stem above stuck with the thin end of the hammer head, the head can not solve while working.

The Kalfateisen are made ​​of forged steel. They have a round head and front are flat and wide. To attach the tow a sharp iron ( Schöreisen ) will be used. There are compacting iron of various thicknesses, which are selected according to the seam width. In the blunt leading edge there are one or more grooves, which are called discounts. They are intended to prevent the tow when compacting the iron passes. In addition, the number of the grooves is a measure of the thickness of the iron. These are accordingly as "a discount ", " two - Off " and so on respectively. In addition to the straight bars there are also bent iron to difficult areas such as edit the transition between deck and superstructure, and there are narrow Butt- iron for the narrow ends of the planks ( butts ).

A Kalfatkiste is a box to which you sit to improve the position when working, for example in the caulking of the soil. In addition, you can keep the rest of the tools and tow in it.

The Dweiel ( Dweidel ) consists of a piece of wool similar to bobble a bobble hat, which is attached to a rod. It is used to lubricate the liquid pitch into the plank gaps. Wool is used because it is more heat resistant than plastics.

The actual Caulk

The Kalfatfuge narrows down and is generally about one-third to half of the plank thickness. The tow is recognized at the Schöreisen, so that the end hangs down. Then the tow is pressed for a few centimeters below the seam with the iron to the bottom plank and pushed up into the seam, so that forms a loop, which is then wrapped with the Kalfathammer. Then, the compression with a stronger iron follows. At the end of the Kalfatnähte were inboard with Kalfatklammern, so-called Sinteln, closed in the Middle Ages. Their shape and number is an archaeological tool for dating.

How strong a tow is taken depends on the type of vehicle and the humidity of the wood. Trawler include robust vehicles and are all year round in the water, so that the planks are not swell when launching. Therefore, the tow is taken very strong.

For boats that were long periods of time on land, must be caulked carefully very much. Too much compression can the planks not a game to sources - in the result, planks can detach from the frames.

The shedding with pitch

On deck you use this one filled with hot pitch steel bag whose outlet diameter can be changed by a sitting front of the outlet iron. If these are not at hand, an old soup ladle is often used. When working on both sides and the bottom of the ship, a pouring is not possible, for obvious reasons, here Dweiel is used. This is immersed in the hot pitch and then fill as much as possible with a rotational motion, the seams. When Verpechen it can lead to accidents due to burns. The übergequollenen edges are scraped after cooling with a scraper.

The casting with plastics

When potting polyurethane rubber ( PU ) and those used silicone-based. Silicone has PU against the disadvantage that it can neither grind nor paint. Its elasticity is however significantly higher, so that the work of the planks can be better balanced. Compared with the traditional Verpechen the plastics have the advantage that they can be much easier, faster processing and cleaner.

Today

In the construction of Arab dhows and other Holzschiffbauten in the Indian Ocean, the method is still in use today. In Germany, the few remaining wooden ships are caulked mainly for repairs, while new buildings in traditional timber construction are very rare.