Microautoradiographic Studies of the Penetration of Alkyd, Alkyd Emulsion and Linseed Oil Coatings Into Wood

By Ralph M. Nussbaum, E. John Sutcliffe, Ann-Charlotte Hellgren

The penetration of wood coating primer products into pine and spruce softwood was evaluated with microautoradiography. ¹⁴C-labeled binders of alkyd and linseed oil were synthesized and used in eight different products. The penetration front in wood is uneven due to a heterogeneous structure with different types of wood cells.

It was demonstrated that conventional solventborne alkyd primers and waterborne alkyd emulsion primers have similar ability to penetrate into wood. Improved penetration was found for products with lower viscosity, such as an alkyd stain and a linseed oil coating.

A priming oil had superior penetration. Generally better penetration was obtained for coatings applied onto sawn and rough surfaces as compared to planed and smooth surfaces.