Can water marks and cloudy patches always be removed from structural glass?

Can water marks and cloudy patches always be removed from structural glass?

Not every cloudy patch is a removable deposit. Runoff can leave residues or carry minerals from adjacent building materials onto glass. Similar marks can arise from scratching, chemical attack, coating deterioration or problems within a sealed unit. A distant photograph may not establish which condition is present.

Assessment considers the location and pattern of marks, available history and the response of a small trial. Compatible cleaning may improve external deposits, but uncertainty about glass type or coatings is not a reason to escalate to stronger chemicals or abrasive treatment. A test should be reviewed after drying as well as during washing.

Marks inside a sealed unit, etched surfaces and damaged coatings fall outside ordinary exterior cleaning. Glazing advice may be needed rather than more washing. Agree expectations around what the trial demonstrates. Cleaning can address appropriate external contamination, but it cannot promise to return every pane to an unmarked state or repair internal defects.