You spend an afternoon cleaning the windows, the sun comes out, and every pane is covered in streaks. It is one of the most common frustrations we hear about. The good news: streaks have a few predictable causes, and once you know them they are easy to avoid.
What actually causes streaks
Residue left on the glass
Washing-up liquid and many glass sprays leave a thin film behind. It looks fine when wet, then dries into smears that catch the light. The more product you use, the worse it gets.
Minerals in tap water
Much of Yorkshire has moderately hard water. As tap water evaporates, it leaves calcium and magnesium on the glass as faint spots and tide marks. Rinsing with tap water can make the problem worse, not better.
Drying too fast
Cleaning in bright sun or on a warm, windy day means water dries before you can wipe it away, fixing any dirt and residue in place. Overcast, still days are best.
Dirty cloths and blades
A cloth that has already picked up grime just moves it around. A nicked squeegee rubber leaves a line on every stroke.
DIY tips for a better finish
- Use very little product: a few drops of washing-up liquid in a bucket is plenty.
- Clean the frames and sills first, so dirty water does not run onto clean glass.
- Work top to bottom, and wipe your squeegee blade after every stroke.
- Finish edges and corners with a dry microfibre cloth.
- Pick a dull, still day and do the shaded side of the house first.
Pets, children and the inside of the glass
Nose prints from dogs and fingerprints from small hands are mostly oils and saliva. A damp microfibre cloth with a tiny drop of washing-up liquid, followed by a dry cloth, lifts them better than heavy sprays.
How the professionals do it
The most reliable way to avoid streaks on the outside of your windows is pure water cleaning. Purified water has no minerals and no detergent, so it dries completely clear, even when left wet on the glass. Frames and sills are cleaned at the same time.
If you would rather not do it yourself, our regular window cleaning covers glass, frames, sills and doors every 4 or 8 weeks, with a 24-hour guarantee if anything is missed.
Quick answers
- Why do my windows streak after I clean them?
- Usually because detergent or tap-water minerals are left on the glass as it dries, or the glass was cleaned in direct sun so it dried too fast.
- Is newspaper good for cleaning windows?
- Not really. Modern newsprint can smear ink on frames and leaves lint. A microfibre cloth or a squeegee does a better job.
- How do professionals avoid streaks?
- Most use purified water, which dries without leaving minerals, or a proper squeegee technique with the edges detailed by hand.