How to remove hard water stains from glass shower doors

What the white haze actually is

Tap water in South Florida carries dissolved minerals, mostly calcium and magnesium. When a droplet dries on glass, the water leaves and the minerals stay. One shower leaves a faint film; a few hundred leave the cloudy white haze and the spots along the bottom of the door that ordinary glass cleaner will not shift.

At first that haze sits on the glass and can be dissolved. Left long enough in a hot, wet enclosure, it starts to attack the surface of the glass itself. That is etching, and it is permanent: there is nothing left on the glass to clean off, because the damage is in it.

Removing mineral deposits

Minerals dissolve in mild acid, which is why the first thing to reach for is plain white vinegar.

1. Protect the stone first. Vinegar and every acidic scale remover will etch marble, travertine and limestone just as surely as minerals etch glass. If the curb, the shower floor or the walls are natural stone, mask them, work from the top down, and rinse any run-off immediately.
2. Warm the vinegar and spray the glass until it is wet.
3. Let it sit. Fifteen to thirty minutes. On a vertical panel the vinegar runs off before it can work, so press paper towels soaked in it against the worst areas and leave them there.
4. Scrub with a non-scratch sponge, not a scouring pad. For stubborn spots, a paste of baking soda and water on the sponge adds a very mild abrasive.
5. Rinse with clean water and dry the glass completely with a microfibre cloth or a squeegee. Glass left to dry on its own starts the next layer straight away.

Commercial lime and scale removers work the same way, faster. Follow the label, keep them off stone, and rinse them off metal promptly: hardware finishes such as matte black and brushed brass do not tolerate strong cleaners sitting on them.

What not to use

• Steel wool and abrasive scouring pads. They scratch glass, and scratched glass holds deposits better than smooth glass does.
• Razor blades, unless you are certain the glass has no protective coating. A blade takes the coating off along with the scale, and a grain of grit caught under it will score the glass.
• Bleach and ammonia near the hardware. They attack metal finishes and seals long before they do anything useful to the glass.

How to tell if the glass has etched

Clean a small area properly, as above, and let it dry. If the haze is gone, it was deposit. If a cloudy, frosted patch is still there and it feels the same as the clear glass around it — no film, no grit — the surface has etched.

Light etching can sometimes be reduced by a specialist glass polish, with results that vary. Deep, widespread etching cannot be cleaned or polished away. At that point the options are to live with it, or to replace the panel. On a frameless enclosure with sound hardware, replacing just the etched panel is often possible.

Stopping it coming back

• Squeegee after every shower. Thirty seconds. Water that never dries on the glass leaves no minerals behind, and this one habit does more than any product.
• Leave the door open or run the fan, so the enclosure dries instead of sitting in humid air.
• A protective glass coating makes water bead and sheet off instead of clinging. It is not permanent and does not replace the squeegee, but it slows the build-up considerably. It is easiest to apply to new glass.
• A whole-house water softener removes the minerals before they reach the glass. It is a bigger decision than a shower door, but it helps every fixture in the house.