Unlike pine and spruce pitch glue, the birch bark tar needs no mixture with coal and fibres. And no animal fat to be flexible.
The uses of birch bark oil:
Leather and wood sealing. (if mixed with linseed oil it goes deeper in the wood)
Insect repellent
Protection from bacterial and fungal infections.
It's flammable and can be used as a candle or lamp oil.
Birch bark tar:
Chewing gum
It's waterproof, and can be used as for example, sealing a birch bark canoe.
And of course as a glue. (Otzi's axe head was hafted with birch bark tar, 5.300 years ago.)
To make tar; boil the oil, let it cool for awhile to see the consistence, if it is too hot, it will be thin. If you let it boil for too long, it will become carbon.
Please only use bark from dead trees.
A better use than a cookie can, could be a (clean) paint bucket, as the lid will stay closer. Make a small hole in the lid, so the smoke can get out, or it will make underpressure, and the lid will come of. but be carefull that it won't catch fire inside the can.
The smoke came out from under the lid in my video and was on fire. (6.04)
The fire was on for about 4 hours. I can't tell you how long you must burn it, it depends on the can size and how hot your fire is.
Thanks again for watching.
Søren
Music: Easy Day, Kevin Macleod