A COMPARATIVE STUDY OF DIFFERENT DRYING PROCESSES USED FOR ARCHAEOLOGICAL WATERLOGGED AND FRESH WOODS

摘要

This paper deals with a comparison between three different processes. Hot air,rncontinuous vacuum and an innovative drying process called Successive Pressure DropsrnDehydration (Déshydratation par Détentes Successives: DDS) were used for dryingrnwaterlogged and fresh wood samples. Measured parameters, as dimensionalrnstabilization using directional (Sd) or volumetric (Sv) shrinkage and color changernmeasurements, are taken into account for evaluating the efficiency of processes.rnSubjective parameters such as cracks, splits and distortion have been also consideredrnwith regard to the waterlogged wood drying objectives. The process showed very goodrnresults that included its high efficiency for dimensional stabilization and color maintain.rnSmall values of shrinkage are obtained from DDS with Sv in the range of 10-13 %rncompared with continuous vacuum drying 11–17 and hot air 18–36 against 8-11 % forrnfreeze-drying. The DDS process is a rapid mean for drying waterlogged and fresh wood.rnIt can also find an important application for many kinds of materials comprising thatrnqualified heat sensitive and commonly freeze-dried.