The 5x5 chair is a typical design project where the limitation is recognised as a challenge. The chair's seat and the back are made of Xilith® tiles dimensioned 5x5 cm as this is the minimal still acceptable dimension for manufacturing since the material itself is very difficult to be manufactured and shaped. Xilith® is the raw material that can be found 300 meters under the ground surface and is comined with a coal. But it is nither the coal nor the wood. At this moment the majority of the raw material is thrown away. From environmental point of view this material generates waste on the earth surface. Therefore the idea about chair design seemed to be very provocative and challenging. The scientific methods of the material’s final surface treatment have been explored so if applied properly the final look can be close to that of ebony.