The cream is not painted onto the glaze, it is under it. Slip is laid on the raw pot, the blue brushed around it, and a clear glaze fired over the lot — so the motif and the ground sit beneath one glassy skin and share every highlight. Over that, a copper compound reduces in the second firing to a metal film a few hundred nanometres thick, and a film that thin interferes with its own reflection. It reads here in a way it never could over white: a thin film needs a ground that gives little back, which is why it wakes on the indigo and stays quiet on the slip.