I have processed the oil from birch bark, but saw you could purchase it online. I thought I would try it and make some hard birch tar for hafting. It took several hours simmering it, evaporating the volatile ingredients. I added finely powdered charcoal and it cooled to a hard consistency, some brittleness, but not as much as pine pitch. It is a smelly process that permeates your hair and clothes and irritates your wife. Now I need to haft a point and assess the strength.