Hello! I teach high school ceramics, with about 50-65 students per semester. I also teach advanced ceramics (wheel throwing) to about 10-15 students per semester. I use plastic bats that are textured on one side and smooth on the other. We have always used the rough sides, but after many years of use, they have worn down and now have smooth rings/cirlcle on each one. I want to keep using them and don't really want to purchase new ones, but students have a hard time centering on the slick centers. I have already tried to roughen one up by sanding the center with 60 grit sandpaper, but it