Notes: took 10 minutes. Never heard the song. Tar = fire-cured condensed resins from evergreen trees and it is very well burning, and sticky like napalm and has its own (very good) characteristic odor. Bunch of birch-branches is a vihta, literally a bunch of birch tree branches Finns used (and still use) to clean themselves in the sauna: whipping oneself with this bunch when sweating makes dirt go away (no soap needed). Sauna in this song may refer to a very old-fashioned type of sauna that is basically a fireplace made of stones and a wooden hut built around it - no chimney at all (holes in the wall let the smoke out and once the stones are hot, water is thrown on them to release the steam - these saunas can still be found in Finland but they light up very easy - but are really good for bathing).