Making Waves: Selected Updates from the Rooswijk Project

On the 8th of January 1740, the Dutch East India Company (VOC) ship Rooswijk weighed anchor and left harbour on the Dutch island of Texel, carrying a varied cargo that included large quantities of silver coins and bullion intended for trade. This marked the start of what  would have been an arduous 9-12-month long journey to Batavia, the then capital of the former Dutch East Indies (now Jakarta, Indonesia). However, by the next day Rooswijk had been driven onto the Goodwin Sands off the coast of Kent and subsequently broke up – sinking with no survivors. Passing into obscurity, it was not until 2005 that the ship was re-discovered following a search by recreational diver Ken Welling.

Lying in approximately 25 metres of water, the remains of the vessel were the focus of two intense excavation seasons in the summer months of 2017-18.

Now almost three years on from the end of practical fieldwork, the project team continues to make fresh discoveries about the ship, its cargo and the people who worked on board. This article provides a general ‘snapshot’ of just a few of these new finds.

The #Rooswijk1740 project is both funded and led by the Cultural Heritage Agency of the Netherlands (Ministry of Education, Science and Culture), working in collaboration with project partner Historic England and UK-contractor MSDS Marine. The post-excavation work is largely undertaken by Historic England in their research facilities at Fort Cumberland.

A cask and its contents

A major element of the Rooswijk’s post-excavation programme concerns de-concreting individual artefacts and conglomerated groups of finds. Concretions form when shells, organisms and sand combine with iron corrosion products from artefacts, creating a rock-hard layer that can be anywhere from 1-10 centimetres in thickness. This effectively encases artefacts in a protective shell, creating an anaerobic (oxygen reduced) environment where decay is slowed and in which artefacts are physically shielded from abrasion, breakage and attack by biological organisms.

The first step of conservation is (excepting instances where artefacts are simply too large or dense) to X-Ray each concretion and interpret contents based on the resulting images.

While some concretions contain only the voids where iron objects once were, others can contain quite literally hundreds of finds.

Layers are removed in a controlled manner, working carefully to record important information as it is uncovered.

The 2018 season of excavation resulted in the lifting of many larger objects and timbers, including two heavily concreted wooden casks which had the potential to provide further information on the contents of Rooswijk’s cargo. Both casks were simply too big for X-Ray analysis and de-concretion was thus undertaken ‘blindly’.

The first cask was fully cleaned in 2019 by previous project members Nicole Schoute and Kim Roche and was found to contain large quantities of iron nails. These probably represent ship’s chandlery intended for use in repairs and maintenance on the outward-bound journey to Batavia.

Work began on de-concreting the second cask in late 2020.

The concreted layers and lumps across its external surfaces were particularly thick, containing a variety of different finds. These mainly consisted of ordinary items encountered across the rest of the site; galley bricks, clay pipe fragments, bottle glass and wooden tool-handles.

However, one unexpected find was a substantial amount of fragile waterlogged plant matter, which may represent traces of external packing material intended to fill the gaps between stacks of casks and better secure them.

It is quite incredible to think that this not only survived the grounding, sinking and subsequent break-up of the ship, but was also preserved underwater and eventually incorporated into the cask’s concretion.

A comprehensive archaeobotanical analysis by Ruth Pelling of Historic England will be forthcoming to identify the plant taxa more specifically.

Two other unexpected discoveries were made during de-concreting. The first of these was an aperture cut into one side of the second cask. This enabled us to confirm relatively early in the investigation that the contents were (again!) iron nails. This feature was seemingly originally sealed by a leather closure, traces of which are still attached to the opening itself. Interestingly, much of the waterlogged plant matter was also concentrated in this area - though the reasons for this are not presently certain.

Additionally, cleaning of one headpiece (cask end) has revealed two inscribed marks, one probably representing that of the manufacturer, the other a crude scratched symbol whose meaning is currently unclear. Project lead Martijn Manders has a personal specialism in casks and cooper’s marks, so further research will investigate whether these marks occur on any other extant casks or are recorded elsewhere.

Future work on the cask will be to de-concrete it fully, record, illustrate and then undertake formal analytical procedures such as sampling for wood identifications and dendrochronology. This not only has the potential to reveal date of manufacture and types of wood utilised on different components of the cask, but also reveal elements of its use-life; if it (or any of its constituent parts) has been repaired, recycled or re-used.

Initial X-Ray analysis revealed two pistols, with copper-alloy fittings, iron barrels and wooden stocks mostly intact.

However, it was during de-concreting that a significant discovery was made, namely that the pistols were wrapped in a layer of textile. Examination revealed the textile to be largely mineralised, meaning a large proportion of the weave is held together (or replaced by) iron corrosion products.

Textile analysis was undertaken by working remotely with specialist Margarita Gleba (UCL/Ludwig Maximilian University of Munich). Francesca Gherardi (HE) took SEM (Scanning Electron Microscope) images of fibres from the warp and weft of the textile. Together with photographs and X-Rays, these aid further analysis and interpretation. The SEM images revealed that the fibres were of sheep’s wool. The plain weave and the fact that one side of the textile appeared to be felted indicated that the textile was probably baise (or baize). Commonly utilised in the 18th century to line the cases of both instrument and gun cases, this loosely woven material was highly durable and provided a non-slip surface (Margarita Gleba, 2020).

The positioning of the pistols would indicate that they were previously in a case. This, and their small calibre (being only 21 centimetres in length), would suggest that they are travelling pistols, probably owned by a higher-ranking member of crew or a passenger. Further research by Dutch weapons expert Jan Piet Puype (former chief curator at the Royal Netherlands Army Museum) will hopefully shed more light on these fascinating artefacts. The next steps will be to undertake wood species-identification on the wooden stocks and to analyse the composition of the copper-alloy fittings through Energy Dispersive X-Ray Fluorescence (EDXRF) spectrometry.

Ongoing work

While the more unique pieces of post excavation research are often highlighted, there are numerous tasks within archaeological assemblages which, while usually less newsworthy, are essential for understandin a site. At present, work continues on a large quantity of structural timbers from the Rooswijk; these are undergoing cleaning, recording and scale illustration by the project archaeologist. In addition, a considerable number of cannon balls and bar shot excavated from a two metre long ‘megaconcretion’ in 2017 are now undergoing conservation.

At present the methods of removing harmful chlorides from iron, a process known as desalination, is a big research topic within conservation. There are several methodologies which can be employed. In the case of the Rooswijk, the decision was made to desalinate the iron using alkaline washes, a method which prevents the iron from corroding while simultaneously accelerating the desalination process. This can take years of monitoring to complete and much like the recording of the ship’s timbers represents one of many day-to-day project tasks.

Closing thoughts

Work on the Rooswijk assemblage has clearly demonstrated that even from studying the tiniest fragments, valuable information about the ship, its cargo and those that sailed upon its final fateful voyage in 1740 is revealed. The case studies presented above illustrate just a few discoveries within the general framework of the project’s post-excavation phase. Although much has been attained and a great deal of headway made, there is still a great deal to accomplish in the coming months.

We go forward with tools ready in hand, intrepid explorers ‘at the chisel’s edge’.

About the authors

Further information

Follow the project on Twitter/Facebook/Instagram: @Rooswijk1740
Explore the Rooswijk virtual dive trail
See 3D models of artefacts from the wreck at the Historic England Maritime sketchfab profile

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