Ornate bead, Byzantine Empire, ~5th century AD?
Classical Antiquity (~800 BCE - 500 AD)
Medieval (500 AD - 1600 AD)
(media.piefed.social)
Yeah, sometimes they apply a clear (removable) coating to the surface first and then write on it.
Other times it's just low-acid inks (or extremely soft-graphite pencil) applied directly to the surface. It's only painted objects that they really can't do that with.