What is the best method of removing furniture polish (containing silicone) from a surface to enable a new coating to be applied? The original finish I applied on this coffee table was 50/50 oil and polyurethane. It is a finish I have used on other timber with success but on Tasmanian Blackwood it shows permanent water marks. The owner tried to polish them out using the furniture polish, and now the water marking seems worse. I want to avoid sanding the finish off completely (due to distance and logistics) and only apply a new polyurethane coating on top. – Bevin Pettitt
Chris Marshall: What probably happened in the first place, was your oil/varnish blend was too thin (either the poly was diluted with too much oil or the finish was applied too sparingly) to build up an adequate film coating over the wood. Water could still penetrate through it, and hence, the rings developed. In his book Understanding Wood Finishing, Bob Flexner makes a couple of suggestions that might be worth a try on this coffee table. Take a clean cloth and dampen it (but not to the point of saturating it) with denatured alcohol. Wipe it gently over the water rings. The alcohol will penetrate tiny openings in the finish coat and help to release and evaporate the water beneath it. But go easy on the alcohol: it can actually draw water into the finish with it if you soak the surface too heavily. You can remove the furniture polish (and the silicone oil it contains) by wiping the coffee table down with mineral spirits. When the water rings disappear, apply a few fresh coats of finish again to restore it and to build up a more durable topcoat. Go with a stronger concentration of poly this time or skip the oil component altogether. If on the other hand the rings just won’t go away, you may have to strip or sand off the finish and start over. (Rings that are black and not hazy white, for instance, are a sign that the wood is damaged. No amount of alcohol will make them disappear.)
