THE POTENTIAL OF THE CANADIAN WINTER CLIMATE FOR THE FREEZE-DRYING OF DEGRADED WATERLOGGED WOOD

Abstract

The winter climatic conditions of much of Canada provide an ideal environment for freeze-drying. We have been attempting to use these conditions for the drying of large waterlogged timbers. In the freeze-drying process the wood is kept in a frozen state and the drying proceeds by sublimation. We are particularly concerned with the treatment of large timber which present great difficulties when treated by the accepted methods. A structure was built to keep snow and rain off the wood but which allowed air to pass over it. The structure was covered with polyethylene sheet to allow the sun to shine on the wood surface and heat it. Weight changes in the wood were measured with a load transducer and temperature wa followed with thermocouple probes. Temperature and relative humidity of the surrounding air were recorded instrumentally. The timbers were of several varieties of wood in various states of decomposition. All of the wood dried quickly and much of the water was removed. This technique appears to have the potential to treat large quantities of timber in an economic and simple way.