Why are streaks such a problem in summer?
The heat is the main culprit
In summer, soapy water dries much faster than in winter. Even if you soap and rinse the window in seconds, the cleaning agent can already partially dry before you squeegee it away. The soap then leaves a white or grayish film – visible as streaks or spots in the light.
Direct sunlight accelerates this process even further. A window on the south side of your house is literally the hardest to keep clean in the summer sun.
Invisible dirt makes it worse
Pollen, fine dust, insects, and air pollution form a thin, sticky layer on the glass in summer. If you start washing with too little water or a dirty cloth, you simply spread that dirt further. The result: streaks that remain visible even after rinsing.
Note: sponges and old newspapers are outdated. Cleaning windows with newspaper used to be popular, but newsprint leaves ink traces on modern window profiles and sponges contain too much soap. Use a microfiber cloth or a professional window squeegee for better results.
The cleaning agent itself can also be to blame
Commonly used all-purpose cleaners or dish soaps leave a soap film, even after thorough rinsing. This film attracts moisture and turns white when it dries. Specific glass cleaners with lower surface tension dry faster and leave less residue.
Proper preparation – the step most people skip
Choose the right time of day
Never wash windows in full sun or during the hottest hours of the day. The ideal times are early in the morning (before 10 AM) or late in the afternoon (after 5 PM), when the temperature drops slightly and the glass is less warm. A cloudy day is even better, but those are naturally rare in summer.
Start by removing dry dust
First, wipe the window dry with a dry microfiber cloth or a soft brush to remove loose dust, pollen, and dead insects. If you don’t, you will create a muddy paste when washing that smears your window instead of cleaning it.
Prepare your materials
Ensure you have everything at hand before you start. Stopping in between to get materials takes time – and in summer, the glass dries faster than you think. What you need: a bucket with lukewarm water, glass cleaner or white vinegar (1 tablespoon per liter of water), a high-quality window squeegee with a rubber edge, and a dry microfiber cloth for the edges.
The right technique: step by step
The S-movement with the squeegee
Professionals use the S-movement: start at the top and make fluid horizontal strokes from left to right, reversing direction after each stroke. Never lift the squeegee completely off the glass – this avoids the small streaks caused by dry contact points.
Wipe the rubber edge of the squeegee dry with a cloth after each stroke. This prevents you from bringing dirt back onto the glass.
Work from top to bottom
Always start at the top and work your way down. Water running down helps with the cleaning. If you start at the bottom, dirty water from above will drip over your clean section.
The edges are the most important part
The corners and the connection to the window frame are where most streaks occur. After squeegeeing, use a dry microfiber cloth to dab the edges dry. Never let water dry in the corners – this always results in limescale rings.
The steps at a glance:
- First, remove dry dust with a dry cloth or soft brush.
- Wet the window with the wash bucket or a sponge – soak it well but do not overdo it.
- Wash the windows, starting at the top and working down.
- Squeegee the windows using the S-movement, starting at the top and working down.
- Dab the edges dry with a clean microfiber cloth immediately after squeegeeing.
- Check in the backlight by standing outside or at an angle in front of the window.
- If you still see streaks, dab them with a dry cloth – this is better than starting over with water.
Vinegar as a secret weapon
White vinegar is an excellent alternative to commercial glass cleaners. It removes limescale, breaks down soap film, and evaporates quickly without residue. Mix 1 part vinegar with 4 parts lukewarm water. The vinegar scent disappears completely once dry.
Common mistakes and how to avoid them
Using too much soap or cleaning agent
More soap does not mean more clean – it means more residue. A few drops of glass cleaner in a bucket is more than enough. If it foams, there is too much.
Using the same cloth for glass and window frames
The window frame often contains grease, rust, or paint residue. If you touch the glass with it afterward, you smear that dirt onto your pane. Always use separate cloths for the frame and the glass.
Washing windows when it is too hot
At 30 degrees and in full sunlight, it is almost impossible to wash a large window without streaks, even for professionals. Plan your washing for the early morning or evening. That is not laziness – it is working smart.
Using cheap squeegees
A 2-euro squeegee does not pull the water away completely – the rubber edge is too soft or not straight enough. Invest in a high-quality squeegee (Unger or Ettore are well-known brands among professionals). The difference is immediately visible.
Frequently Asked Questions
How often should I wash my windows in the summer?
In summer, every 4 to 6 weeks is a good guideline. On the street side or near a garden, it may be more frequent due to pollen, insects, and fine dust. A quick interim dry wipe with a microfiber cloth can already remove much of the buildup without a full wash.
Can I just use dish soap to wash windows?
You can, but it is not ideal. Dish soap foams heavily and leaves a soap film that dries quickly in the sun into streaks. If you do use it, use only 1 drop for a full bucket and rinse thoroughly. White vinegar or a specific glass cleaner provides better results.
My windows get dirty again quickly. What can I do?
After washing, you can treat the glass with a hydrophobic coating or nano-product for glass. This allows water and dirt to slide off faster, keeping the window clean longer. A good water-repellent coating works for 3 to 6 months and saves you several washes per year.
What do I do with stubborn limescale streaks?
Limescale streaks (white deposits from hard water) are best removed with white vinegar or a specific limescale remover for glass. Let the product sit for a moment, then wipe with a microfiber cloth in circular motions. Avoid abrasive agents or steel wool – they scratch the glass.
Is it safe to wash high windows myself?
For windows on the ground floor, you can do it yourself. As soon as you need a ladder or work at height, the risk outweighs the convenience. Professional cleaning services have the right equipment and training to do this safely – and they do it much faster and without streaks.
Can I use a pressure washer on windows?
Only for an initial rough cleaning of the exterior glass, at low pressure and from a safe distance. A pressure washer can damage the seal between the glass and the window frame, which causes moisture problems over time. After spraying, you will still need a squeegee to avoid streaks.
Crystal clear windows all summer – without you having to do a thing
Now you know how it’s done. But honestly, washing windows in the summer heat is one of those chores you’d rather leave to someone else. Especially if you have high windows, a busy schedule, or simply want to enjoy the summer more than investing time in it.
L&S Housekeeping washes your windows at the right time of day, with professional equipment and without streaks. So you can relax and enjoy the beautiful weather – through crystal clear windows.
Request your cleaning help or call us directly.
