How to clean windows without streaks: step-by-step method and tools

You can clean windows without streaks if you do it in the shade or on an overcast day, first remove dust and clean the frames, and only then clean the glass. Lukewarm water with a small amount of cleaning product, used according to the label, is enough for the glass. Remove the water with a squeegee in continuous strokes, wipe the rubber blade after every stroke and dry the edges with a dry microfibre cloth.

When to clean windows

The biggest cause of streaks is a solution that dries on the glass before you remove it. So avoid direct sunlight and hot days, when the glass is warm. The ideal time is an overcast day without rain, or the part of the day when the relevant side of the building is in shade. South- and west-facing windows are usually best cleaned in the morning, east-facing windows in the afternoon.

Do not clean windows on the outside in freezing weather, as the water freezes on the glass and the frame. In winter, therefore, leave the outside until a warmer day and clean only the inside. During prolonged rain there is no point in cleaning the outer glass at all, as the raindrops will soon leave new marks on it.

Tools

For ordinary windows in a flat, simple equipment is enough:

• a bucket of lukewarm water,
• a few drops of washing-up liquid or a window cleaner dosed according to the label,
• a washer pad or a soft sponge that will not scratch the glass,
• a squeegee with a straight, undamaged rubber blade, ideally the width of smaller panes,
• two microfibre cloths, one for the frames and one dry cloth for drying the edges,
• a vacuum cleaner with a crevice tool or a soft brush for the frame grooves,
• a toothpick or a thin wooden stick for the drainage holes,
• a seal-care product, if the window manufacturer recommends one.

Step-by-step method

1. Take down the curtains, clear the windowsill and place a towel under the window to catch any water running down.
2. Open the sash, vacuum or sweep out the frame grooves and remove cobwebs and insects.
3. Clean the frame, sash and windowsill with a soft cloth and lukewarm water. Frames are cleaned before the glass because dirty water runs down from them.
4. Wet the glass thoroughly first with a washer pad or sponge. Never wipe off dirt when dry, as dust and sand act as an abrasive.
5. Place the squeegee against the top edge of the glass and pull it in continuous strokes, each slightly overlapping the previous one. Wipe the rubber blade with a cloth after every stroke.
6. Dry any remaining drops at the edges and in the corners with a dry microfibre cloth.
7. Check the glass from the side against the light and buff any streaks with a dry cloth.
8. Finally, wipe the water from the windowsill and put the curtains back.

If you are cleaning both sides, clean the outside first and then the inside. You can then easily tell where the streaks are: if you buff them from the inside and they do not disappear, they are on the outside.

Frames, seals and hardware

Plastic frames do not need any special chemicals. The profile manufacturer VEKA recommends wiping them with a clean soft cloth and lukewarm water, optionally with a little neutral cleaner, and, if you have used a cleaner, rinsing the frame with clean water (VEKA: Care and maintenance). According to the same manufacturer, abrasive powders, steel wool and brushes, solvents, thinners, aggressive products and steam cleaners do not belong on plastic, aluminium or wooden frames.

VEKA also advises treating the seals with a product intended for the purpose so that they stay flexible, vacuuming the frame groove while the sash is open, clearing the drainage holes with a thin wooden stick and lubricating the moving hardware at least once a year with an acid-free and resin-free oil or grease. For wooden and aluminium windows, follow their manufacturer's instructions, as surface finishes differ.

Blinds, insect screens and windowsills

When you clean windows, it is worth cleaning what is on and around them at the same time. Otherwise, dust from the blinds or the screen will land on the clean glass the first time you air the room.

• Interior blinds: first vacuum them or wipe them dry in the closed position, then wipe the slats with a damp cloth on both sides. Clean the blinds before the glass.
• Insect screens: remove them if the design allows, rinse them with lukewarm water and a soft brush, and leave them to dry before putting them back.
• Exterior windowsills: clear them of leaves and deposits and check that water drains freely from the sill.
• Interior windowsills: wipe them according to the material; for stone and wood, use only a product approved by the manufacturer.

After painting or renovation, there are often drops of paint, sealant or silicone on the glass and frames. Soak them first and remove them carefully so that neither the glass nor the frame is scratched.

Roof windows

With roof windows, the glass is usually the most exposed to rain and dust, but it is hard to reach. In its cleaning tips, VELUX states that dirt should not be removed from the glass without first wetting it with water, that no chemical products or products with abrasive particles should be used on the glass, and that the glass should not come into contact with sharp objects, including jewellery, or with silicone (VELUX: Care and maintenance). When painting or repairs are being carried out near the window, it recommends protecting the glass with a clean film.

Roof windows often have a cleaning position in which the sash is rotated and locked, so you can clean the outer side from the inside. You will find the exact procedure for your type of window in the manufacturer's instructions; do not climb onto the roof to clean it.

The most common mistakes that leave streaks

• Too much cleaning product. Foam and detergent residue are hard to remove and show once dry.
• Cleaning in the sun. The solution dries before you can remove it.
• Dirty water. Change the water as soon as it turns grey, especially after cleaning the frames.
• A dirty or damaged squeegee blade. Dirt on the blade leaves lines, and a jagged blade does not wipe cleanly.
• Glass before the frame. Dirt then runs from the frame onto the clean glass.
• Wiping when dry. Dust and sand can scratch the glass.
• A scraper on large areas. It is better to soak dried drops of paint or sealant first and remove them carefully, as a sharp blade can scratch the glass.

Safety when cleaning windows

When cleaning windows, do not lean out, and do not stand on the windowsill or on a chair. Use stable steps with a firm support and, for higher windows, ask another person to hold them. Do not use improvised means to reach the outside of fixed, non-opening windows on higher floors without safe access.

If there are small children at home, never leave an open window unattended, even for a moment, and put the steps away immediately after the work. When working with cleaning products, ventilate the room, wear gloves and read the label before diluting.

How often to clean windows

It depends on where you live. Windows near a busy street or a building site get dirty faster than those facing a quiet courtyard. A thorough clean in spring and autumn is usually enough, with the inside cleaned more often as needed. Window cleaning is often part of seasonal cleaning, see spring cleaning: a plan for a weekend or a whole week or pre-Christmas cleaning, and it belongs on the deep cleaning checklist.

If you have large, high or hard-to-reach windows, you can include window cleaning in an ordered deep cleaning.