Thank you for the excellent and informative article. The part about keeping particles suspended in liquid makes sense. I probably would have had mine designed with flat bottoms, howevr, because I wouldn’t want a sand floor in my kitchen, or dining room. LOL I liked the one at your link that was “designed for show”. Beautiful. Elegant.
And nowwe know why so many of them are found broken. These are the equivalents of today’s plastic milk jugs.
I thought the article covered everything except the actual maker of the individual units! It answered a lot of questions I had but was too lazy to look for! LOL!