You pick a bright Saturday, spray the windows, wipe them down and step back to admire your work. Then the sun moves around the house and suddenly every streak is visible.
So you blame the cleaner. Or the cloth. Maybe next time you'll buy a different spray and give it another go.
But professional window cleaners say there's another reason this happens, and it has surprisingly little to do with how expensive your cleaner is. When you clean the window, and how quickly you get the liquid back off the glass, can make a much bigger difference.
Why sunny windows are harder to clean
The problem starts when the cleaning solution dries on the glass before you've finished removing it.
On a warm, sunny day, that can happen surprisingly quickly. Sunlight heats the glass, the water evaporates faster and whatever is left behind — cleaner, dirt or minerals from the water — can dry into the familiar streaks you see when the light catches the window.
Carolyn Forté of the Good Housekeeping Institute has warned about cleaning hot windows for exactly this reason. Consumer Reports gives similar advice: a cloudy day is a better time to clean because the solution stays wet for longer.
That's why the best window-washing weather isn't necessarily the kind you'd choose for a day outside. A cool, overcast morning is ideal. If the sun is out, clean the side of the house that's in the shade instead.
The squeegee matters more than endless polishing
There's a reason professional window cleaners tend to work with a squeegee rather than spending ages polishing the glass with a cloth.
The squeegee gets the dirty water off the window while it's still wet. That gives the solution less time to dry on the glass in the first place.
Your cloth still matters, of course. A dirty cloth can leave grime behind, and a worn squeegee blade can drag lines across the pane. But constantly changing cleaning products won't fix either of those problems.
One small habit is particularly useful: wipe the squeegee blade regularly with a clean cloth. And keep your finishing cloth separate. Use one cloth for the initial cleaning, then a clean, dry microfiber cloth for the edges and frame.
Your water could be leaving spots behind
There's another reason a perfectly clean window can still look marked once it dries: the water itself.
Tap water contains minerals, and those minerals can remain behind when the water evaporates. If you live in an area with hard water, you may notice this as small spots or a cloudy film.
Distilled water contains far fewer dissolved minerals, so it can be useful if this is a recurring problem.
The same goes for soap. You don't need a lot. Too much can leave its own residue, which means you're creating another film that has to be removed.
Try this next time
The whole process can be much simpler than it looks:
- Wait for a cloudy or shaded part of the day.
- Add only a small amount of dish soap to your water.
- Start at the top and work down.
- Use a clean squeegee to remove the water while the glass is still wet.
- Wipe the edges with a separate, dry microfiber cloth.
If your windows always seem to look worse after you've cleaned them, don't automatically reach for another bottle of spray.
Next time, change the timing first. Cooler glass gives you more time to wipe the water away before it dries.