I took a class from Dawn Candy. She uses Amaco velvet underglaze & plainsmen underglaze. She said it was a runny clear glaze that gives the bleeding effect when that clear glaze is over underglaze with blue in it. ( If I’m remembering correctly) She mixes blue in with the black underglaze. So far, it hasn’t worked for me. I think she said to add water to the underglaze which is trailed onto her green ware. I didn’t do that part. Maybe that’s why my hasn’t bled at all. She fires to cone 6, electric kiln. I have a runny clear recipe from her that she shared with us. I’m sure she wouldn’t mind me sharing it, if anyone is interested. Dawn also uses another super runny glaze that she wouldn’t share because it can really mess up the shelves!