"... the robe that met his hand was made of black velvet lined with silk. A closer look showed that it was sewn together in one piece without either stitch or needlework." Hmm - sewing without stitching - is that like welding?

Also, for the first three books, the main character is described as 'a sturdy black-haired youth.' On page 1 of book 4, he's become 'a tall, sturdily built youth in his middle teens, with untrimmed brown hair..' Wizarding depletes hair color?