Blowline contra Blender

The objective of a joint project by the University of Göttingen, the WKI Braunschweig and the IHD Dresden was to examine the influence of blowline and blender gluing on the physical/technological board properties and dimensional stability of MDF under the impact of different atmospheric conditons. It was found that the gluing process has a major influence on MDF made of pinewood fiber and bonded with melamine-fortified urea formaldehyde resin. MDF produced with the blender method of gluing has higher bending and transverse tensile strengths as well as lower thickness swelling values than equivalent boards produced with the blowline method. However, pinewood MDF made with fibers glued in the blowline seems to have greater dimensional stability under differential atmospheric conditions. Without exception it was found that beech and pine MDF produced with the blowline method have greater dimensional stability than boards produced using the blender method. A direct comparison of different types of wood showed that MDF made of pine is generally the most dimensionally stable. The results of the research provide no clear conclusions as far as the mechanical and technological properties of MDF are concerned in respect the way in which MDF deforms in response to differential atmospheric conditons.