Streaks: the #1 problem with window cleaning
Glass isn't a passive surface โ it reflects everything, including the smallest imperfection. A cloth with a single fibre of lint leaves streaks. A leftover product traces show up against the light. The challenge isn't "cleaning the glass" but doing it WITHOUT leaving a mark.
In short
- Squeegee + water + 5% vinegar + microfibre = professional formula, zero streaks.
- Never clean glass in direct sunlight: the product dries before the final pass.
- Lugano frequency: inside 1-2 months (kitchen more often), outside 3 months (pollen + lake humidity).
- Top-down movements, 2 cm overlap between passes.
- For windows above 2.5 m or full-height glazing: professional kit needed (telescopic pole + reverse osmosis).
The squeegee technique โ how the pros do it
Common mistakes that produce streaks
- Newspaper: the vintage myth. Works but leaves ink that sticks to the frame edges. Microfibre is better.
- Old towel: leaves lint on glass. Only professional microfibre.
- Cleaning in sunlight: solution dries before you can squeegee. Always clean glass in shade or early morning.
- Multi-purpose spray: contains additives that leave a film (necessary for surfaces like stainless steel but terrible on glass). Avoid.
- Squeegee with worn blade: micro-cracks in the rubber drag without drying. Replace the blade every 12-18 months.
Heavily soiled or scaled glass
For balcony glazing exposed to weather, old water spots, limescale or silicone residue:
- Pre-treat with 5% citric acid (50 g per litre warm water): spray, leave 5 minutes, then squeegee normally.
- Persistent stains: baking-soda paste + water, damp microfibre, gentle circular motion.
- Silicone residue: 70% isopropyl alcohol on a cloth, then standard procedure.
When to hire a professional
Ideal frequency by zone
| Window type | Inside | Outside |
|---|---|---|
| Kitchen | 2-3 weeks | 3 months |
| Bathroom | 1 month | 6 months |
| Bedrooms and living areas | 1-2 months | 3-4 months |
| Balconies and terraces | 1 month | 2-3 months |
| Continuous glazing (Lugano centre/Paradiso, lake view) | 1 month | 1-2 months (pollen + lake humidity) |
In Lugano, lake humidity raises the outside frequency by 30-40% compared with a city away from water. It's a real factor, not marketing.
Preventive maintenance
- Always open before cleaning the inside: wipe the frames with a barely-damp cloth. Dust and pollen settle there and return to the glass at the first breeze.
- Dry frames after every rainfall: prevents permanent water marks and silicone mould.
- Wooden shutters: dry cloth + specific oil once a year (never steam โ it swells the wood).
- Insect screens: small-nozzle vacuum every 3 months, disassemble and tub-wash once a year.
Frequently asked questions
Why do windows have streaks after cleaning?
Main causes: leftover product on the glass, paper-based drying that leaves lint, washing in direct sunlight (dries too fast), dirty microfibre. Water + 5% vinegar + squeegee = no streaks.
How often to clean windows in Lugano?
Inside every 1-2 months (more for kitchen). Outside: every 3 months in Lugano due to pollen and lake winds. For offices and Airbnb: every 1-2 months outside too.
Can I use a steam cleaner on windows?
Yes, especially for dirty or encrusted windows. Steam + squeegee is the standard professional combo. Don't aim the jet directly at silicone seals or painted frames.
Sources & references
- [1]Suva โ Working at height, safety in external window cleaningSuva โ accessed 2026-05-08
- [2]ECHA โ Acetic acid REACH profileEuropean Chemicals Agency โ accessed 2026-05-08
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