Check whether the bowl has a water-repellent, darkened surface from an alkali treatment
Look for a glossy, burnished, or sealed appearance rather than a raw clay finish
Inspect for mineral or ash-based residue associated with alkali processing
Compare the clay body for signs of chemical alteration, such as a hardened or vitrified surface layer
Examine whether the bowl shows traditional alkali pottery traits from its cultural origin
Look for documentation, maker’s notes, or provenance stating alkali treatment
Test only through professional analysis if needed, such as laboratory compositional testing