For the record: The only pants Jonathan Adler owns are white jeans. The designer, turning 52 in August, calls himself a “prissy potter” — he’s not about to sacrifice style just because he’s working with clay. Please. Jonathan rolls up the sleeves of his pale blue button-down shirt, declaring that he’s going to make an urn. Today’s challenge isn’t perfecting a piece of pottery, even though what he creates will likely become a prototype for his ceramics collection sold around the world. That’s second nature to the artist. Instead, he pauses, his face turning contemplative.