I started out practicing my hollowing on a piece of red oak. It had some pretty bad checks in it so I didn't think if I ruined it it was much of a loss. Cracks got pretty bad. I did pretty well on the hollowing and got it down to a bit less than 1/4" (this is all hand hollowing and not my rig). After I finished I did an experiment with the old rust and vinegar ebonizing treatment. I applied about four coats and got this color. I made a little ash collar and now I have another unfinished piece of junk. Oh well good practice. it is 4 3/4" X 7 1/2" with a 1 7/8 opening. Any comments for future work of this kind welcome.