Judy Musicant on sun 8 oct 06
I had this problem years ago. It sounds like your liner glaze isn't =
completely vitrified. For future pieces, test some other liner glazes. =
You should find one that doesn't seep at your firing temperature.
For those already made, you can try to spray the bottom with an acrylic =
spray - they come in a matte or shiny finish. You can get them at an =
art or crafts supply store. I've had success with that.