Hämäläinen, K. and Kärki, T. 2012. Usability of Wood as a Direct Printing Medium. Baltic Forestry 18(2): 316-327

Versatility in the appearance of wood and added value to interior decoration markets could be achieved by printing grain patterns of different species or images directly onto wood. The problem is how to transfer a high quality image or print sustainably onto wood, which is porous, heterogeneous, dimensionally unstable, non-white and rough. The surface properties of wood affect its printability. Optimal adhesion is essential for print quality, as too high ink absorbance can cause spreading and too low ink absorbance pale prints. Different printing techniques have different requirements on materials and production. Non-impact printing techniques provide the best basis for wood printing. Direct printing on wood has potential to provide efficiency to production. Inkjet printing on wood with different mechanical or chemical surface treatments, and wood plastic composite material gave good results that encourage further studies on the subject. Sanding the wood surface perpendicular to the grain gave the best overall printing quality. Spreading parallel to the grain could not be avoided totally, except in cases where the wood was treated hydrophobic, when in turn the adhesion of ink was not sufficient. The grain pattern of the underlying wood stayed clearly visible in the printed images.

Keywords: wood veneer, WPC, adhesion, printing, ink.