Two requests appeared in my YouTube channel's Q&A comment section, one was how to remove hard carbon from a pipe's rim, and the other how to remove hardened tar at the bottom of a mortise. Both are easily done with an inexpensive, specialized tool anyone can make, and don't require much practice or skill to use.
This video covers rim carbon removal:
https://www.youtube.com/watch?v=iT9TJfpU2xU&list=PLFwwtvtKlXW-HJ9mijb5fRm-ncucTB80C&index=3&t=0s
And this one how to clean a mortise:
https://www.youtube.com/watch?v=qBa6GElg6ns&list=PLFwwtvtKlXW-HJ9mijb5fRm-ncucTB80C&index=3
This video covers rim carbon removal:
https://www.youtube.com/watch?v=iT9TJfpU2xU&list=PLFwwtvtKlXW-HJ9mijb5fRm-ncucTB80C&index=3&t=0s
And this one how to clean a mortise:
https://www.youtube.com/watch?v=qBa6GElg6ns&list=PLFwwtvtKlXW-HJ9mijb5fRm-ncucTB80C&index=3