Hard water stains come off in stages. Accurate Glass & Mirror, a Bergen County NJ glass shop, starts with distilled white vinegar held on the glass by a soaked cloth for ten to fifteen minutes, then a non-scratch pad and a rinse. Repeat before escalating. If haze survives several rounds, the minerals have etched the surface and cleaning is no longer the answer.
There is a two second test for this. Wet the panel and look again. Deposits sitting on top of the glass turn clear the moment they are wet, because water fills the rough scale and light passes straight through. Etching does not behave that way: if the cloudy area still looks cloudy under running water, the mineral has already reacted with the surface and taken a bite out of it. Deposit comes off with patience. Etching is a change in the glass itself, and no product on any shelf reverses it.
Run the test on the worst area rather than a convenient one. Panels commonly carry both conditions at once, with sound glass up high and damaged glass along the bottom, so the honest answer comes from whichever section has taken the most water over the years.
One check before the vinegar comes out: if the glass carries a protective coating, skip the acid soak and ask the fabricator what that coating tolerates. Contact time does the work here, not pressure. Vinegar that runs down the panel in ten seconds accomplishes nothing, so soak paper towels or a cloth, press them flat against the face and let them sit. On heavy scale, a paste of baking soda and water applied over the top afterward gives a mild abrasive assist that will not scratch glass. Work in small sections, rinse completely between rounds, and dry the panel before judging the result, because wet glass always looks better than it is.
Three moderate passes remove more than one violent one and carry none of the risk. Skip the steel wool, the scouring powder and the utility blade: they will take the deposit off and leave behind scratches that scatter light worse than the stain ever did.
Etched glass can sometimes be improved by a professional restoration polish, which removes an extremely thin layer of the surface with cerium oxide and a machine. It is skilled work, it can leave optical distortion if it is done unevenly, and it is not something to try on a tempered panel with a household drill. Where etching is deep or covers most of the face, new glass in the existing opening is usually the more sensible path, and the hardware and enclosure often stay exactly as they are.
Glass tolerates brief exposure to household vinegar without any trouble. What it can harm is everything around the glass: natural stone thresholds, some grout, sealant joints and certain finishes on metal. Keep it off marble entirely, wipe overspray from hardware quickly, rinse everything when you are done, and never leave an acidic solution to dry on any surface.
Because water keeps landing there. The lower third of a door, the hinge side and the strip above the bottom sweep hold water longest, so those areas run more evaporation cycles than the rest of the panel and build deposits fastest. If the pattern repeats after every cleaning, look at where water sits when the shower stops rather than at your cleaner.
If the haze stays cloudy under running water, that panel is etched and no product is bringing it back. Panels are cut and edged at the Lodi bench, and a free in-home measure tells you whether the opening and the hardware already there can take new glass. Call (201) 460-1313.
