Can someone with access to google please search gwern.net please find the page where Gwern shows there's no documentary trace of this actually happening and link it please? I'd find it myself but bing isn't up to the task and Google is blocked in China.
>>barry-+(OP)
I tried looking for it with Google and couldn't find it, either on or off his site. I did find an interesting article about the obsolete practice of sanding floors to clean them: https://www.gwern.net/Sand