I used to scrape my bamboo pretty aggressive, but these days, I'm not. I leave the nodes very proud, basically not touching them at all. I only scrape, or even sand, between nodes, just enough to remove the outer waxy rind on the bamboo. If you don't remove the rind, the bamboo won't take any finish. I don't do much anymore. Go easy with the scraper, as it leaves little marks on the bamboo... potential weak spots.