The international comparative wood treatment study WOAM Freemantle 1987 - Trondheim 2012

The project The international Comparative Wood Treatment Study was developed and launched under ICOM-WOAM by D. Grattan, Canadian Conservation Institute and F. Schweingruber, The Swiss Federal Forestry Institute. The project started in 1983 and at the Woam Conference in Freemantle in 1987 the many experiences and results was presented. The project aimed at obtaining a better common understanding of various treatments of waterlogged wood and to understand how and why treatments functioned. This project involved ten conservation laboratories in nine different countries - Canada (2 labs), France, Netherlands, Japan, Germany, Australia, Austria, England and Norway. In all 26 different treatment programs - of which 23 treatments involved PEG. From 1989 the wood samples have been kept for perpetuity at Vitenskapsmuseet (Museum of Science) in Trondheim, Norway in a climate controlled environment.
This paper evaluates and documents changes in the condition of the wood samples from the WOAM project in 1987, with focus on the PEG/water treated samples. In Trondheim, visual assessment and evaluation of the samples was performed, without removing the wood samples from the climate controlled storage. Measurements of weight, dimensions and color were made, and the samples were photographed. Research was performed in the archives. The core samples were assessed visually nad by MALDI TOF, Matrix Assisted Laser Desorption Ionization-Time-of-Flight, to investigate the distribution of the hight and low molecular PEG in the samples.
With the exception of the samples treated with low molecular weight PEG (i.e. PEG 400), there are very few and very small changes in the samples 25 years (1987-2012) after treatment. Low molecular weight PEG has a good bulking effect on well-preserved wood, but has a negative effect on samples of deteriorated wood. PEG 400 can even flow out of the wood sample leaving liquid PEG as a pool on the shelf if the concentration of PEG 400 is high, and leaving the whole surface on the sample sticky. When combining high and low molecular weight PEG, the low molecular weight PEG will weaken the compression strenght of the PEG i.e. the wood structure. The conclusion is that the best treatment for deteriorated wood will be using a high molecular weight PEG combined with freeze-drying without any addition of low molecular weight PEG.