FWIW.
If folks are experimenting with Kaolin, just thought I would point out that it's a very broad term.
If you visited a ceramic supplier there would be a range of kaolins with different properties, fineness, particle size. From domestic to English Grolleg... Calcined would behave very differently as it is fired, sintered.....
Don't know anything about how it's being used here, but might be worth the investigation...