re: Sanding inside a bowl

I bought something once, so long ago I don't have a clue as to it's name, but it felt spongy, and gritty at the same time. They came in coarse, to very fine IIRC. I got a coarse, and it wasn't worth a hoot to do anything. I abandoned the idea.

George, the operative word is abandon and I’m pretty sure that’s where I’m at.   I’ve found that even a spongy disc won’t do what I want because of the angles involved.
Literally every turned bowl I’ve seen has a smooth transition from the ‘bottom’ to the side of the bowl.  My bowls have a flat bottom with an acute angle up and because of the way they are made and the curve on the riser even 2” discs won’t fit right.
I think I’ll just have to continue hand sanding with paper such as belt sander paper