Specific Gravity of Inner and Outer Larch Bark

Larch bark is an interesting resource for the production of insulation panels. As it consists of a sugar-rich inner bark and an outer bark containing more durable components, there is the requirement to separate these compartments. Additionally, bark is often mixed with wooden pieces after industrial debarking processes. In this study, the wet density, dry density, and specific gravity of wood, whole bark, and inner and outer bark are investigated using the pycnometer method, which has been proven to be adequate for the volume measurement of irregularly shaped, light objects such as bark flakes. Soaked with water, the density of the inner bark is highest, followed by wood, and the lightest is the outer bark. Because of different moisture contents, the wet density is not directly comparable. The outer bark sucked up less water than the inner bark. Focusing on the specific gravity, the wood is the heaviest, followed by the outer bark and the inner bark. The differences are significant for both methods, displaying a promising physical basis for separation methods based on density differences. These might be a means to pick out more durable and less hygroscopic outer bark particles from a bark mixture in order to produce optimized bark composites.