After a year of cleaning windows across Dublin, we can tell you the single most common mistake people make at home, because we see its results every week: spraying window cleaner onto the glass and wiping it with a cloth.
Why It Fails Every Time
Two things go wrong at once. The solution starts drying into the glass while you are still wiping, which is where streaks come from. And the cloth sheds as you work, which is where the lint comes from. You finish with a pane that looked better mid-wipe than it does five minutes later — a result familiar to anyone who has cleaned windows on a sunny Saturday and wondered why they bothered.
The Method That Works
Professional technique is a sequence, not a product: mop, squeegee, cloth. Wet the glass properly with a mop and mild solution — washing-up liquid is genuinely all you need. Pull the water off with a squeegee in overlapping strokes, so no water is left on the glass when the pull finishes. Then use a dry cloth only on the edges and sill, never across the middle of the pane.
Technique Beats Product
Notice what is missing from that method: any special product. The order of operations and the squeegee discipline matter far more than anything you can buy. It is the same on our jobs — the skill is in leaving zero water behind after the pull, because whatever stays on the glass dries as a mark.
When to Stop DIY-ing
Ground-floor glass responds beautifully to the method above. Upstairs, over extensions, and anywhere involving a ladder is where we would gently point you to our honest take on when professional cleaning earns its cost — or straight to the quick quote form if the streaky spare-room window has already beaten you twice this year.