Ash is another important parameter to measure in carbon. The level of ash-content is partly dependent upon type of biomass, and it's origin and composition, as input into the pyrolysis process. Since we are focusing on steel- and metallurgic applications it is of importance to keep a low level of ash-content, as ash is partly seen as a potentially pollutant substance in steel/iron-making processes. By only using stem-wood from pine and spruce as feedstock, we secure highest level of quality of biocarbon with a minimum of ash-content.