[davegardner]

From what I've discovered, it must be a Japanese Lacquer Brush. Traditionally these are made from the hair of pearl divers, "selected as the finest and densest fibre."[1] Another reference I found quotes that "They say that the salt strengthens the hair"[2]

[1] http://spitalfieldslife.com/2012/01/12/pedro-da-costa-felgue...

[2] https://www.nippon.com/en/views/b02309/

[unwind]

Thanks! I guess that makes sense, but I didn't think it through. I wonder what the original author thinks of that, do they expect their audience to be aware of this? Weird.

[JKCalhoun]

Ha, ha, author wants the reader to perk up and do some googling... ;-)