Investigation of primer/preservative basecoats for timber using vacuum impregnation

A novel low-cost treatment process was developed to improve the long-term durability of factory furnished joinery components for exterior use. This process involved the vacuum pressure impregnation of combined preservative and primer basecoats in a single treatment operation. A comprehensive comparison was made of the effect of vacuum impregnation and dip coating, the current method of application, on the adhesion properties of the basecoats. This work was carried out on both as-received and surface-treated pine samples. The latter being surface activated using a flame ionisation technique prior to impregnation. The strength and failure modes of the coatings were evaluated on samples in both wet and dry conditions. It was found that vacuum impregnation improved the adhesion of the basecoats, particularly in the wet condition, and that the use of a flame ionisation surface treatment prior to the application of the coating improved coating penetration, thus enhancing long-term preservation of the wood.