I am dipping and brushing, but it's mostly where I leave white unpainted bisque that I see differences in how the glaze absorbs ......thicker in the white areas even when drying overnight.
As to the why: Several reasons: we make a lot of beads and if you dump all the under glazed beads together to bisque, the colors rub off on each other. Even when we separate by color, sometimes chunks of underglaze stick to their neighbor bead leaving the clay showing on one bead and a lump on the other.
Another reason is that I am sometimes afraid I will break the greenware, or I have spent too much time on the greenware, and if something goes wrong at the painting stage I can wash everything off and start over. Often I do underglaze the greenware, but other times it's just not the best solution for me and my work.
Glad to know about the rounding tool. I think I will try the rolled method also. I know everyone has to kind of find their own way, but I do not like wimpy rims, which mine seem to be. Alabama,by "wide" rims are you saying you extend the rim beyond the mold them trim later?
I tried again with a coil at the top outside of the bowl shape, (with the hump form still inside, and everything upside down,) I ribbed to blend into the body of the bowl. When it firmed up a bit, I took out the hump form and turned right side up. Then I had to add a tiny coil to fill in between original rim and coil addition. A lot of work...........but it actually turned out better than when I tried to add the coil to top rather than side of the rim. Where do you add your coil and at what point in the process? Thanks I am more of a wheel person, learning backwards.......