As professional window cleaners, we get asked about streaks all the time.
People clean their windows, step back and think they have done a good job. Then the light changes. The sun hits the glass. Suddenly there are smears everywhere.
The truth is that streak-free window cleaning is not just about the product you use. It is also about how much cleaner you use, what cloth you use and when you clean the glass.
Generally, for glass cleaning you do not need a strong commercial product. A simple homemade cleaner can work well for marks and regular upkeep.
A simple DIY window cleaning recipe
For a basic homemade window cleaner, you can use:
- 2 cups of warm water
- 1/2 cup of white vinegar
- 1/2 cup of rubbing alcohol
- 1 spoonful of corn starch
Add everything to a spray bottle. Shake it well. Then spray a small amount onto the glass and wipe it clean.
The warm water helps dilute the mixture. The vinegar helps cut through light grime. The rubbing alcohol helps the cleaner dry faster. Corn starch is an unusual ingredient, but it can help polish the glass and reduce streaks when used properly.
Make sure you shake the bottle before each use. Corn starch can settle at the bottom, so it needs to be mixed through again.
How we recommend using it
The biggest mistake people make is using too much cleaner, you really only need a light spray. The problem is too much cleaning solution causes it to run down into the frames and tracks, and it can leave more residue behind, which is one of the main causes of streaks.
It’s best to wipe away loose dust from the window frame and sill before you spray the glass, otherwise you risk dragging dirt across the window. Which is not what you want.
Use a clean microfiber cloth and wipe the glass in steady strokes. Once the cloth gets too damp, swap it for a dry one. A second dry cloth can also be used to buff the glass once the main marks are gone.
The timing matters too. Avoid cleaning windows in direct sun where possible. Hot glass makes the solution dry too quickly. That is when streaks are more likely to appear.
Why windows still look streaky after cleaning
When we see streaky windows, it usually comes down to residue.
That residue might be from old cleaning products. It might be from dirty water, dust, hard water marks or a cloth that was not clean enough. It can also come from using too much spray.
Paper towels can also cause problems. It often leaves lint behind, especially on larger panes of glass. For small indoor jobs, a good microfibre cloth is usually a better option.
Another issue is reusing the same cloth for too long. Once it becomes wet or dirty, it stops picking up residue properly. It starts spreading it around instead.
That is why clean tools matter just as much as the cleaning solution.
DIY cleaner vs store-bought window cleaner
Store-bought window cleaners can be useful. Many are made with ingredients that help cut through grease, dissolve residue and dry quickly. Some include ammonia, surfactants, solvents, fragrances and preservatives. Some also include ingredients that help reduce dust or future build-up.
These products can be stronger than a homemade cleaner. That can help when the glass is greasy, heavily marked or overdue for a proper clean.
The trade-off is that some commercial cleaners use stronger chemicals. These may not be ideal for every home, especially if you are sensitive to fragrances or solvents. There is also the packaging to think about, as most products come in plastic spray bottles.
A homemade cleaner is simpler. It is not always as powerful, but it is usually enough for regular touch-ups. You can also keep reusing the same spray bottle, which helps cut down on waste.
For everyday glass cleaning, DIY can work well. For tougher jobs, exterior glass or windows that have not been cleaned for a long time, a professional clean will usually give a much better result.
A professional window cleaner’s final tip
After more than a decade running a professional window cleaning business in Melbourne, I have learned that streak-free glass usually comes down to the basics.
Use less cleaner. Use a clean cloth. Avoid direct sun. Make sure you are lifting dirt off the glass, not just moving it around.
Use a light amount of cleaner and always work with a fresh cloth. If possible, avoid cleaning windows in direct sunlight and remember, the goal is to lift dirt and residue off the glass, not just spread it around.
Happy window cleaning!
This content is provided for informational purposes only and is not a substitute for professional advice. AFP editorial staff were not involved in the creation of this content.
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