An Investigation of Consolidants Penetration in Wood. Part 1: General Methodology and Microscopy

Consolidation of degraded and frail wood by impregnation with synthetic and natural polymeric compounds in solution is one of the most important operations of active conservation of wooden cultural heritage. The effectiveness of such a treatment depends essentially on the consolidant retention, penetration and uniformity of distribution, aspects that could be cumulated in the term of impregnation level and practically influenced by many and various factors. The purpose of this work was to look at some practical possibilities of characterising the impregnation level achieved in some consolidation treatments with different solutions of a frequently employed synthetic polymer (Paraloid B72) and waxes (beeswax and modified paraffins as melts or in combination with linseed oil) using a simple optical microscopy technique in conjunction with an original method of samples preparation. For this purpose were used small samples of sound, not degraded spruce (Picea abies Mill), which were impregnated by short time immersion. The examination in transmitted light (TLM) of the cross-cut micro sections and in reflected light (RLM) of the wooden blocks allowed the visualisation of the consolidation products and their distribution in the wood structure, but this was easier for the consolidants with high solids content (waxes), which partly filled the lumens, and much more difficult and relative in the case of the diluted Paraloid solutions which did not fill the lumens but only impart a very shiny, highly reflective aspect of the treated areas. In order to objectively appreciate the retention and penetration of consolidants into wood the method using ImageJ, a useful image processing software, was used to process the micrographs so that some quantitative estimations of the variation of the impregnation level with the penetration depth were obtained