Some amazingly well-preserved wooden artifacts have been found in water-logged environments over the past couple hundred years, and the technology to keep them well-preserved has continued to improve. The only problem is: older technologies may be destroying the artifacts they were invented to protect.
Ceremonial Wagon From Oseberg. The wood fibers of the richly decorated ceremonial wagon are disintegrating because of the early 20th century preservation method. © Museum of Cultural History, University of Oslo / Eirik Irgens Johnsen
This little wagon is from the Oseberg Boat Grave, a ninth century Viking burial in Norway. After its discovery in 1904, the artifact was disassembled, and treated with a supersaturated solution of potassium aluminium sulphate dodecahydrate (alum) at 100 degrees Centrigrade. The alum crystallized the wood, stabilizing the structure. The wagon was reconstructed, using metal pins and screws, and finally covered in lacquer.
Unfortunately, the long term effects of the alum have been devastating to the wood, completely destroying the cellulose fibers, and significantly dropping the pH values thereby degrading the lignin. Researchers at the Helmholtz Association of German Research Centres led by Hartmut Kutzke (University of Oslo) have identified the issue using infrared studies, and are currently working on a solution: to develop an artificial wood, by "growing a bionic skeleton framework" inside the degraded wood.
Oseberg Boat Grave. The most famous archaeological trove of Oseberg is a well preserved and richly decorated Viking ship, in which two high-ranking women were buried. The ship was not treated with alum. © Museum of Cultural History, University of Oslo / Eirik Irgens Johnsen
With a little digging, I found three unpublished papers describing the research stored on the Wood Science for Conservation of Cultural Heritage website:
- The presence of sulfuric acid in alum-conserved wood: Origins and consequences, Susan Braovac & Hartmut Kutzke.
- The use of an electric field for the removal of alum from treated wooden objects, Iben V. Christensen et al.
- New materials used for the consolidation of archaeological wood-past attempts, present struggles, and future requirements, M. Christensen, F. K. Hansen and H. Kutzke
Comments
To see the Oseberg ship and wagon in Oslo is an adventure and a joy. It’s the Viking world in all its splendor. Wish it to exist for a long time.