If you’re applying over an existing varnish, ensure the surface is sound, if not the coating should be removed. Test for compatibility. For bare wood, unless you’re using a clear surface primer, we recommend thinning the first coat of all our varnishes. This promotes good penetration of the surface and adhesion of subsequent coats. After this first coat, the surface will appear rough – as the exposed ends of the wood absorb the varnish and lift – sand this smooth with a medium grade sandpaper.