Hard Water Stains vs. Etched Glass: How to Tell the Difference
Every week someone calls us convinced their shower door or picture window is ruined. Most of the time it is not. The white haze, the rings and the streaks that will not wipe off are usually mineral deposits sitting on top of the glass, and those come off. A smaller number of doors have gone past that stage to etching, where the minerals have started to eat into the glass itself. Knowing which one you have saves you either a jar of cleaner or the cost of new glass.
What a hard water stain is
Tap water carries dissolved calcium and magnesium. When a drop dries on glass, the water leaves and the minerals stay, as a tiny white ring. Thousands of drops over months of showers build those rings into a film. Soap scum, which is soap reacting with the same minerals, binds to it and holds it in place. The film is a deposit, not a change to the glass, and a paste cleaner with a mild abrasive lifts it off.
What etching is
Left long enough, especially where water is very hard, mineral deposits become alkaline enough to react with the glass surface. The glass loses its polish in the shape of the deposit. Once that happens, cleaning removes the mineral but leaves a dull ghost of it behind, because the surface underneath is no longer smooth. No cleaner reverses etching; the options are polishing the glass with a cerium compound, which is a professional job, or replacing it.
The two-minute test
- Clean a hand-sized patch with A-MAZ Water Stain Remover on a damp pad, working until the pad glides freely.
- Rinse and dry the patch completely. Wet glass hides everything.
- Look at it with a flashlight held almost flat against the glass. Deposits that are gone leave clear glass. Etching shows as a faint dull pattern in the same shape the stains were, and it feels very slightly rough under a fingernail.
If the patch is clear, the rest of the door will be too, and you are done for the price of a jar. If you see the ghost pattern, the glass is etched, but clean it anyway; an etched door that has been cleaned and sealed looks dramatically better than a stained one, and most people decide it does not need replacing after all.
Why some doors etch and others never do
Time and water hardness are the main factors. A door in a soft-water area can go years without a problem. A door on well water or in a hard-water city like Las Vegas, Phoenix or much of Southern California can begin etching within a couple of years if deposits are never removed. The other factor is heat: a hot shower speeds the reaction, which is why the lower half of the door, where the water hits hardest, etches first.
How to make sure it never gets there
Deposits cannot etch glass they are not sitting on. Cleaning a couple of times a year and keeping the glass sealed is all it takes. Ultra Gloss Sealant fills the pores of the glass so water beads and runs off instead of drying in place; on a shower door it lasts six to nine months. A squeegee after each shower helps too. The Shower Restoration Kit is the remover, the sealant and two pads together, which is everything one shower needs for the year.