shellac シェラック

but the “varnish” was likely to have been an oxidation product in the same family
as those shellac-like substances turning up in fast-food restaurants of late.

シェラック自体を知らなかった
弦楽器の塗料などに使う樹脂
https://media1.britannica.com/eb-media/17/125017-004-7205E396.jpg