I've a friend who's a silversmith. She says that according to her elderly teacher, back in the day you just sketched in pencil right onto the metal; you could wipe it off with a damp cloth if you messed up.
Well, that was perhaps the most interesting video I’ve seen on YT. Almost unique in that I wanted more when, for most videos, I’m screaming less. Congratulations to the production team including getting the choice and volume of the music just right (for me). If you haven’t been and are able to go, please visit the V&A; a stunning museum with more to see than you can fit into a day. Go for a coffee to the tiled room; I defy anyone not to spend a lot of time there.
The melting temperature of the silver is much higher than the melting point of the enamel, so the kiln temp is set high enough to melt the enamel but not high enough to damage the silver. I imagine before modern kilns with thermostats it must've been a really nerve-wracking job!