Why Do My Windows Still Look Cloudy After Cleaning?

1 day ago

3 min read

Updated: 5 hours ago

You wash the window, it dries, and it still looks hazy. It is one of the most common things people ask us about, and it is frustrating because it feels as though the cleaning did not work. Usually the cleaning worked fine. The haze is not dirt.

The three usual causes

Oxidation from aluminum screens or frames, which leaves a chalky white film on the outside of the glass.
Hard water deposits, which leave white spots or a cloudy patch where water has dried again and again.
A failed seal in a double-pane window, which lets moisture in between the panes.

Each has a different fix, so the first job is to work out which one you are looking at.

Table for diagnosing cloudy window glass by where the haze is, the likely cause and what fixes it — Start with where the haze is. That tells you most of what you need to know.

1. Oxidation from screens and frames

Aluminum does not rust, but it does oxidize. Over the years, aluminum screens and storm window frames develop a fine gray-white powder on their surface. Rain washes that powder onto the glass below, and wind blows it against the pane.

A home repair column in the Daily Herald describes the result well: heavy gray deposits on glass behind aluminum screens, caused by oxidation particles from the screens combined with airborne pollutants.

How to recognize it: the haze is on the outside, it is worst directly below or behind a screen, and it feels slightly rough. Normal washing dulls it but does not remove it. The fix is a dedicated treatment, which we describe on our oxidation removal page.

Double window in a living room with spotless glass and a view of trees — What the glass should look like once the film is gone.

2. Hard water stains

Hard water is water with a lot of dissolved calcium and magnesium, as the U.S. Geological Survey explains. When it dries on glass, the minerals are left behind. One drop leaves a faint ring. A sprinkler hitting the same pane every morning for a summer leaves a crust.

How to recognize it: round spots or a cloudy band on the lower part of the window, often in line with a sprinkler head or below a dripping air conditioner or gutter. Fresh spots come off with a proper clean. Deposits that have been there for years can etch into the surface, and then they can be improved but not always erased.

The lasting fix is to stop the water reaching the glass. Adjust the sprinkler, repair the gutter, then have the deposits removed.

3. A failed seal

Modern windows are made of two or three panes sealed around the edge, with a gap between them. If the seal fails, humid air gets into the gap and condenses. InterNACHI, the association of home inspectors, covers the causes in its article on condensation in double-paned windows.

How to recognize it: the fog or streaks are between the panes. You cannot touch them from inside or outside. They may come and go with temperature. No cleaning will reach them. The glass unit, though not necessarily the whole window, needs to be replaced by a glass company.

Pair of double-hung windows with a clear view of a lawn and trees — If a clean window still looks foggy from both sides, look between the panes.

Two more possibilities

Interior film. Cooking, candles, fireplaces and new furnishings can leave a greasy haze on the inside of the glass. It comes off with a thorough interior clean.
Cleaning residue. Too much soap, or paper towels and household sprays in direct sun, can leave streaks that look like haze. A rinse with clean water and a squeegee sorts it out.

A quick test you can do

Rub a small area on the outside with a damp cloth. If it changes, the problem is on the outside surface.
Do the same inside.
If neither side changes, the problem is between the panes.

What not to do

Do not reach for a razor blade, steel wool or an abrasive powder. The glass industry's cleaning bulletin, published by the Glass Association of North America and shared by the International Window Cleaning Association, warns that scrapers can scratch glass. Scratches are permanent. Stains usually are not.

Common questions

Can oxidation come back?

Yes, if the old aluminum screens or frames stay. Replacing or sealing them stops it at the source. Regular cleaning keeps it from building up.

Will vinegar remove hard water spots?

It can help with light, fresh spotting. It will not remove heavy or etched deposits.

Can you tell me which problem I have?

Yes. Andy can usually tell within a minute of looking, and he will be straight with you if it is something cleaning cannot fix.

Get a second opinion on your glass

Request a free estimate and mention the cloudy windows. If it is oxidation or hard water, we can treat it. If it is a failed seal, we will tell you so you can call a glass company.