The ceramicist uses human ashes.

Ash, such as tree ash, is a normal ingredient in the glaze. Why not use human ashes? Have you ever had some ashes -- were you gauche enough to call them cremains? -- and wondered what to do with them? Was it awkward or properly solemn or did you screw it up like the Dude in "The Big Lebowski"? How would you feel about your loved one being reformed into pottery?