Microscopic Study of Waterlogged Archeological Wood Found in Southwestern China and Method of Conservation Treatment


  • Jian Qiu
  • Rui Min
  • Monlin Kuo


Waterlogged wood, bacterial degradation, microscopy, phenol-formaldehyde, discoloration


Thousands of waterlogged wood pillars beneath crop fields were discovered during the 2008 excavation of an archeological site in southwestern China. Specimens were studied with scanning and transmission electron microscopes, and 2.5 cm x 2.5 cm x 5-cm specimens were dehydrated with methanol followed by treatment with neutral phenol-formaldehyde (PF) resin. The wood, identified as Pinus kesiya var. langbianensis, was severely degraded by bacterial surface erosion and tunneling of cell walls. Bacterial tunneling was more frequently observed near the cell corners with thick walls. Bacterial degradation of cell walls was accompanied by accumulation of degradation products and bacterial slime in cell lumens. Neither brown-rot nor soft-rot decay was detected in the wood. The wood samples gradually darkened after sampling, but removal of degradation products with methanol and a brief 2% oxalic acid treatment reversed the discoloration. The average specific gravity and crushing strength of the waterlogged wood were 0.25 and 7.1 MPa compared with 0.37 and 33.7 MPa of normal wood of the same species. Treatment of the waterlogged wood with neutral PF resin increased specific gravity to 0.44 and crushing strength to 12.8 MPa. The PF treatment minimized shrinkage and stabilized wood color of the waterlogged wood.


Björdal CG, Nilsson T (2001) Observation on microbial growth during conservation treatment of waterlogged archaeological wood. Stud Conserv 46:211-220.nBjördal CG, Nilsson T, Daniel G (1999) Microbial decay of waterlogged wood found in Sweden. Int Biodeterior Biodegradation 43:63-73.nBlanchette RA (2000) A review of microbial deterioration found in archaeological wood from different environments. Int Biodeterior Biodegradation 46:189-204.nChristensen M, Hansen FK, Kutzke H (2010) New materials for the consolidation of archaeological wood—Past attempts, present struggles, and future requirements. Proc Wood Science for Conservation of Cultural Heritage, International Conference on Wooden Cultural Heritage, Hamburg, 2009. http://woodculther.com/wp-content/2009/christensen (5 September 2013). http://woodculther.com/wp-content/2009/christensen'>http://woodculther.com/wp-content/2009/christensennFors Y, Sandström M (2006) Sulfur and iron in shipwrecks cause conservation concerns. Chem Soc Rev 35:399-415.nFuruno T, Imamura Y, Kajita H (2004) The modification of wood by treatment with low molecular weight phenol-formaldehyde resin: A properties enhancement with neutral phenolic-resin and resin penetration into wood cell walls. Wood Sci Technol 37(5):349-361.nGodfrey IM, Richards VL, Cha MY (2012) The post-treatment deterioration of marine archaeological wood—Where to now? 13 pages in The MUA Collection. http://www.themua.org/collections/items/show/1246'>http://www.themua.org/collections/items/show/1246nHamilton D (1999) Methods of conserving archaeological materials underwater sites. Conservation Research Laboratory, Center for Marine Archeology and Conservation, Texas A&M University. http://nautarch.tamuedu/CRL/conservation manual/file6.htm (24 August 2013). http://nautarch.tamuedu/CRL/conservationmanual/file6.htm'>http://nautarch.tamuedu/CRL/conservationmanual/file6.htmnHocker E, Almkvist G, Sahlstedt M (2012) The Vasa experience with polyethylene glycol: A conservator's perspective. J Cult Herit 135:S175-S182.nHolt DM, Jones EBG (1983) Bacterial degradation of lignified wood cell walls in anaerobic aquatic habitats. Appl Environ Microbiol 46(3):722-727.nKim YS, Singh AP (1999) Morphological characteristics of compression wood degradation in waterlogged archaeological pine wood. Holzforschung 53(4):381-385.nKim YS, Singh AP (2000) Micromorphological characteristics of wood biodegradation in wet environments: A review. IAWA J 21(2):135-155.nMin R (2009) The Haimenkuo archaeological site of Jianchuan County, Yunnan Province Archaeology 7:17-24 [in Chinese].nSchmidt O, Liese W (1982) Bacterial decomposition of woody cell walls. International J of Wood Preservation 2:13-19.nSchmidt O, Nagashima Y, Liese W, Schmidt U (1987) Bacterial wood degradation studies under laboratory conditions and in lakes. Holzforschung 41(3):137-140.nSchmitt U, Singh AP, Thieme H, Friedrich P, Hoffmann P (2005) Electron microscopic characterization of the 400,000-year-old wooden Schoningen spears. Holz Roh Werkst 63:118-122.nSmith DM (1954) Maximum moisture content method for determining specific gravity of small wood samples. Rept. No. 2014. Forest Products Laboratory, For. Service, U. S. Department of Agriculture, Madison, WI.nSun Q, Chen T, Wang CM (2007) Study of variation of density and mechanical properties of plantation Pinus kesiya var. langbianesis with different ages. Wood Processing Machinery 2007(3):19-23.nThomas RJ, Nicholas DD (1966) Pit membrane structure in loblolly pine as influenced by solvent exchange drying. Forest Prod J 16(3):53-56.nUnger A, Schniewind AP, Unger W (2001) Conservation of wood artifacts: A handbook (Natural science in archaeology). Springer-Verlag, Berlin, Germany.nWang C, Wang J, Jiang H (2003) A study of the comparative anatomy of P. yunnansis Franch. stem under different habitats. Pages 345-352 in Proc. 9th Annual Meeting of ChineseWood Science Soc., 30May 2011, Harbin, China. The Chinese Wood Science Society, Beijing, China.n






Research Contributions