Oops!
Sometimes the magic works, and sometimes it doesn’t. In 40 years or so of making custom tile murals, I have found very few brands of tile that I couldn’t work on. But some will just not stand up to refiring. They’re almost always, like these samples for a bathroom vanity tile mural, made by hand either by an individual or in a small factory. They were made from wet clay on a slab roller, not dust pressed like commercial tile. This puts different stresses on the fired tile. They’re perfectly fine and durable as is, but they won’t survive the china paint firing. So now we’re looking for a different tile for this job.