Why Streaky Windows Happen (Even After Cleaning)

If your windows streak even after cleaning, it's rarely bad luck — it usually traces back to one of a few specific causes.

Common Causes

• Cleaning in direct sunlight: solution dries too fast before it can be wiped properly, leaving streaks behind.
• Using the wrong cloth: cotton and paper towels leave lint and fibers; microfiber or a proper squeegee technique avoids this.
• Too much solution: excess product takes longer to dry and is more likely to leave residue.
• Hard water in the cleaning solution itself: if tap water is used for the final rinse, mineral content can leave its own marks.

Why Professionals Get a Different Result

Proper squeegee technique (a single clean pull, not multiple overlapping wipes) combined with purified or deionized water for rinsing avoids most of the common causes of streaking altogether.

If You're DIYing

Clean on an overcast day if possible, use a squeegee rather than cloths for the final pass, and avoid over-applying solution. See our DIY vs. professional guide for more on when it's worth doing yourself.