actually, there is a reason to use the glaze, depending what filler you use. Bondo brand is intended to be DTM (Direct To Metal). In my world, most work is done outside and normally primed by end of the day whether done or not (also why I got in a habit of using spray cans). That means I am often glazing over primer for touch-ups. For dings, I don't usually remove old paint, just rough it up and hit it with glaze. I am using 3M Platnum Plus filler and glaze. Both are supposed to adhere to cured paint, primer, etc. So I could have just used filler. The glaze is nicer to lay a thin coat though.