We had complete Wooden cabinets from 1961 that were unpainted, so we sanded and did numerous coats of primer in order to cover the knots and oil stains. Now I believe we could have made use of a knot blocking solution. We also painted each of the backs and interiors http://cabinetpaintcan98367.bloginwi.com/15201577/the-2-minute-rule-for-painting-kitchen-cabinets-white