Thanks Ted for this information.
Granted, it's a niche market, but if you google these words, you'll see the current use of these words and videos showing this enameling being done on newly made expensive watch faces.
That famous New York jewelry company still makes the bracelets, over 50 years after their debut, and this paillonne enameling looks like a full layer of foil (not like the tiny designs as seen on the watches). Since the bracelets are 18k, the only reason I can see why they are using a full layer of foil is because the slight wrinkling of it makes sort-of a random texture under the enamel.
I think I saw a video of using the foil to completely cover guilloche, which just seems curious, because all these trinkets are made of 18k gold. Why place foil over 18k guilloche?