How do I clean windows without streaks?

Streaks are dried residue. Anything left behind on glass — detergent, dissolved dirt, cloth fibres, minerals from hard water — becomes visible the moment it dries. The whole technique below is about removing water from the glass before it can evaporate on its own, and using as little cleaning product as will do the job.

What you'll need

• Bucket of warm water
• Washing-up liquid (a few drops only)
• Squeegee
• Two microfibre cloths
• Scrim or newspaper for buffing (optional)

Step by step

1. Wait for an overcast day or work on the shaded side of the house.In direct sun the water evaporates before you can remove it, and streaks are guaranteed.
2. Brush or vacuum loose dirt, cobwebs and grit from the frames and sill first.Grit dragged across glass by a squeegee scratches it.
3. Add just a few drops of washing-up liquid to a bucket of warm water.More detergent means more residue. It should barely feel soapy.
4. Wash the glass with a cloth or applicator, working over the whole pane including the corners.Corners hold the most dirt and are where streaks appear first.
5. Squeegee from the top down in overlapping strokes, wiping the blade dry after every pass.A wet blade redeposits dirty water. This one habit fixes most streaking.
6. Run the squeegee across the bottom edge, then dry the frame and sill.Water sitting on the frame will run back down the glass as it dries.
7. Buff any remaining marks with a dry microfibre cloth.Use a clean, dry one — a damp cloth just spreads the residue.

Tips

• For hard-water spotting that won't wash off, a 50:50 white vinegar and water solution dissolves the mineral deposit. Rinse afterwards.
• Two cloths, one damp and one bone dry, will do a decent job on small panes without any squeegee at all.
• Clean the inside with horizontal strokes and the outside with vertical ones — when a streak appears you immediately know which side it's on.
• Paper towel and glass are a bad combination: it sheds fibres and leaves lint on every pane.

Common mistakes

• Cleaning in direct sunlight — The single most common cause of streaks — the glass dries faster than you can wipe it.
• Too much detergent — The excess dries as film. A few drops per bucket is genuinely enough.
• Not wiping the squeegee blade between strokes — You redistribute the dirt you just removed.
• Using the same cloth wet and dry — The 'dry' buff just moves water around.

Questions people ask