"Woodborg" wrote: (clip) what would i use to burn the inside of a curve
surface such as a bowl.
^^^^^^^^^^^^^^^^
I haven't done this, except in my head, but this seems like it ought to
work:

Drill a hole about 1/2" diameter in a piece of sheet metal. Then remove
metal from outside the hole until a sort of teardrop shape: narrow on one
side, and broad on the other. Hold the broad side in a pair of Vise-grips
(or make a handle) and press the thin edge against the wood inside the bowl.
It should be almost as thin as a wire at the narrowest part, which contacts
the wood, and stiff enough to let you press on it. Preferably, use
stainless, which has a low thermal conductivity. Next choice, ordinary
steel. Do not use aluminum or copper.