Clay dome to make the system as hermetic as possible, a stick grid to separate the burning chamber from the receptacle chamber, and a solid receptacle. Got it. I'd fire the dome so that it can be reused (with less debris in the final tar), but then it would be a pseudo-pot, so I think that it would defeat the whole "no pot" scenario.
After the successful attempt, it was kind of fired. I stored it for later and plan on stuffing it with fresh bark for another round, but this will have to wait a bit. If something interesting comes out of it I'll post an update.
Maybe use a sheet of bark with holes poked in it as a filter or strainer in addition to the twig grid? Under it to catch finer particles. Maybe make it double layer and roll it into a cone, the outer layer as a funnel and the inner layer poked full of holes, kind of a like a coffee filter.
I am currently trying to make birch pitch myself with modern tools and in my last attempt I got nothing while using roughly the same amount of bark as you are. Your video helped me realize that all my potential pitch escaped as gas and simply burned off. Well at least I carved a nice boomerang/throwing stick while waiting for my pitch. :D I assume you do this experiment because of the fact that use of birch pitch predates use of pottery in the archeological record by tens of thousands of years? Very interesting. :)
This reminds me about the study on how Neanderthals were able to make birch tar. However, the researchers used flat stones with dirt/loam instead of a cone of clay.
I put a link to a recent study about this in the video description, is that the one you were thinking of? If not, and you can still find it, I'd be thankful for a link!
