Abstract: A method of compressing at least one flat wooden element having knots therein to permanently increase the hardness of the wooden element. The method includes the steps of inserting an elastic material layer between a pair of spaced apart press plates which are moveable with respect to each other, the elastic material layer being softer than the wooden element. The wooden element is then interposed between the elastic material and one of the press plates, and the pair of press plates displaced toward each to a predetermined spacing thereby compressing the entire surface of the wooden element and elastic material layer, the thickness of the elastic material layer in the compressed state being at least one-half the thickness of the compressed wooden element. Portions of the knots in the wooden element are forced out of the element and into the elastic material layer without being broken to shivers by the pressure exerted thereon.