That chalky film is essentially limestone—the same stuff that builds up in caves and on ancient ruins. When hard water evaporates, it leaves behind calcium and magnesium ions that laugh at ordinary detergent. Think of it as the patina of daily life, but one we’d rather scrub off.
Fun fact: The ancient Romans actually used calcium deposits to waterproof their aqueducts. You, however, are just trying to get your wine glass crystal clear.
