I have just discovered your site as I was looking for a solution to the valley I always seem to get when shaping my bowls. I am not sure what I am missing but I know it is happening every time. Maybe There is a better description.
Starting with about a 3" wide base I will open the bowl with an already bowl shape bottom. Raising the walls I try to keep a cylindrical shape and once the walls are at a desired thickness I will take a metal rib and from top to bottom shape the bowl. Only each time somewhere during the shaping I end up with 2 little valley's near the base which I can not get rid of.
It would be great if you had some suggestions, I just finished studying at Haliburton School of The Arts in Ontario Canada and have set up a small studio at home, the only thing I am missing is classmates or teachers to discuss any issues or feelings with. Anyway let me know if you come up with anything :)
I'm trying to picture what you are referring to, but I'm not sure what part of the pot has the two little valleys.
If they are inside the bottom of the pot you can usually smooth them with a sponge or a rib. If they are on the outside of the pot you could do the same while supporting the walls from the inside with your other hand.
If I'm way off base, maybe you could send me another message with a photo or two of what it looks like when this happens and I'm sure I can find you a solution.