Any previous finish such as varnish, stain or paint should be completely removed prior to treating with a woodworm treatment. Once the woodworm treatment has been applied to all areas and allowed to dry, the wood can be re-coated or painted. Some people manage by only removing the paint from the affected area then treating. The potential problem with this is that the woodworm may have penetrated further than the area treated, and the re-finished area may not totally blend in with the old finish.