Chemical protection of historic timber structures: Results and future needs
M Kisternaya, V Kozlov
The paper concentrates on the analysis of the effectiveness of chemical protection for timber structures in the Russian State Museums “Kizhi” (Karelia) and “Vitoslavlitsy” (Novgorod).
The condition of historic timber was tested at the monuments treated with PCP, borax, potassium carbonate, boric acid, Pinotex chemicals in the 1970-80. Long-term analysis revealed that in many cases the deep-treatment with PCP and borax chemicals proved to be efficient only for a short period of time. Profound activity of wood-borers was noted in the structures deep-treated with preservative chemicals.
Deep treatment caused emergence of new cracks of timber and enlargement of existed ones. Changes in absorption and desorption processes are occurred. Changes in color are easily seen in a majority of the treated monuments. The treatment also deteriorated the ecological situation. Modern chemicals (Rocima-243, Rocima-293, ULTAN (CCA-type), Ventti, etc.) were tested on pilot structures established in the “Kizhi” museum in 2005. The results of the microscopical investigation of the samples after 3-year - long exposure are given. The chemicals appropriate for restoration and conservation of wooden architectural monuments are presented. The need of environmentally save approaches to preserve an essential part of our cultural heritage – historical wooden structures is emphasized.
Keywords: historic timber structures, preservatives, long-term effectiveness, Scots pine (Pinus sylvestris L.)