Researchers at Columbia University used a voxel printing techniques to create digital wood, complete with internal grains and external colour textures.

The block of digital wood is based on an olive wood sample, with its grain pattern replicated exactly throughout, as well as other colour gradients. To achieve this result, the team used state of the art technologies in 3D printing.

First, they sliced the wood in ultrathin slices of 27 micro-metres (0.027 millimetres) with a computer controlled CNC mill. These wood slices were photographed by an overhead camera, which allowed capturing consecutive slices of wood as they were cut. The 230 images were fed into a Stratasys J750 PolyJet 3D printer. This printer is capable of printing various colours and materials using voxels. Voxels are 3D pixels, the smallest element in which an object can be divided in the design process.

To achieve multimaterial printing, the printer sputters droplets of dissimilar materials on the build tray. It then mixes the droplets to produce smoother segments, rather than the pixilated appearance the wood would otherwise have. The layer is finally cured with ultraviolet light before the machine moves on to the next layer.

To test if the blocks had the right internal multicoloured structure, the researchers dipped some in liquid nitrogen and shattered them. Other blocks were broken using a chisel. The experiment shows that the differently coloured resins form a continuous grain. In addition to blocks, the researchers also created digital wood shaped like an alligator.

Photos: Columbia University