The analysis of caulking material in the study of shipbuilding technology


  • R.T.J. Cappers
  • E. Mook-Kamps
  • S. Bottema
  • B.O. van Zanten
  • K. Vlierman


An analysis was made of 182 caulking samples that belong to 98 different shipwreck (fragments) excavated in the Netherlands from 1942 onwards. These ships represent several different types and were built between the second half of the 9th century and the beginning of the 20th century.

The caulking samples consist of mosses, other plant species, hair and amorphous material. Also taking into account mixtures and considering Sphagnum separately, we recognized ten different categories of caulking material. Besides Sphagnum, 35 different bryophytes could be identified: l liverwort, 7 acrocarpous mosses and 27 pleurocarpous mosses. With the exception of unintentionally gathered species, these mosses are easily gathered, owing to their relatively large size and their growth-form in connection with abundance. Caulking samples from ships that were built between the 9th and the middle of the 13th century are composed of mosses that were purposely gathered in (deciduous) woods. From the 13th century onwards, mosses were gathered in wetter environments. From the 14th century onwards, most moss samples contain only one species. Sphagnum becomes predominant and also Drepanocladus aduncus and D. exannulatus remain well represented. One possible explanation is that the availability of woodland mosses in sufficient amounts decreased. However, it is more likely that, along with the improvement of the caulking technique, the folIowing properties may have become increasingly important: I) long fibres; 2) absorbency and 3) absence of contaminants.

Both the identification of mosses and pollen analysis can provide information on the type of environment and the possi ble area where the caulking material was gathered. The composition of some caulking material indicates that it was gathered from a variety of locations. This can be explained by the large quantities required for the caulking of a single ship. Also the replenishment of stock supplies will have produced mixtures of species from different origins.