When I looked at this again, years later, I was struck by how much the network of red looks like it was painted - the lines look like brush strokes. Now, I know that is probably not what it is - the crackle thing makes sense, but...what if? What if a resist was painted on, then the rest enameled, then fired? The thing that bothers me is the uniformity of the line thickness. It does change a little, but compared to other examples it seems pretty uniform. The ends of lines are wide and often look like brush strokes. Just an idea. EDIT: never mind, that's a silly idea.