Water repellent treatments for catamaran grade <i>Bombax ceiba</i> Linn. (Spermatophyta/Dicotyledoneae) wood

Abstract

Water repellency effectiveness (WRE) of four chemical formulations, namely polymeric methylene diisocyanate (PMDI), cashew nut shell oil (CSNL), varnish and chromium trioxide, was assessed on Cooper-Chrome-Arsenic (CCA) treated <i>Bombax ceiba</i> wood. Fifteen cycles of repeated wetting and drying were performed on water repellent coated and untreated wood. Water repellency was very high in the first cycle and then declined in all the coating system in subsequent cycles. After 10^th cycle WRE became constant for all the systems. PMDI exhibited highest water repellency followed by chromium trioxide, CSNL and varnish. With the application of water repellent formulations, water uptake can be reduced considerably, which will maintain buoyancy of wood. The water repellents apart from reducing water holding capacity also reduces leaching of preservatives from the structures, which resulted in enhancing the durability of wood.