Streaks are about order and weather, not about the cleaner
Windows usually get washed twice: once for the glass, once for the streaks left by the first attempt. The cause is rarely the product. It is usually one of two things. Either the frame and seals were not de-dusted, so their dirt travelled across clean glass. Or it was too sunny and warm, and the water dried before the squeegee reached it.
That is why this list does not start with the glass. Pick your moment, remove dry dirt, wash the frame — and only then work on the glass.
When to do it
On an overcast, still day, or while the window is in shade. In sun or wind the solution dries in seconds and leaves lines. Frost is its own problem: water freezes on the glass and rubber seals stiffen in the cold.
The tools that actually change the result
A squeegee with an undamaged blade, two microfibre cloths — one for washing, one dry for the edges — a non-scratch sponge, a bucket and a brush for the frame channels. Newspaper works worse than a squeegee and leaves ink marks on light-coloured frames.
The order for the glass
| Step | How | Mistake |
|---|---|---|
| Wet it | Sponge the solution over the whole pane, top to bottom | Using too little water: dry grit scratches |
| Squeegee | Overlapping strokes from the top down, wiping the blade after each | Pulling the squeegee across dry glass |
| Edges | Dry cloth around the perimeter and into the corners | Leaving drops on the edge to dry as marks |
| Check | Look at the pane at an angle and from both sides | Judging the result only against the light |
What people miss about modern frames
A frame has drainage slots — narrow openings along the bottom of the outer face. They let out water that gets inside the profile. Blocked with dust, they cause a puddle on the sill and damp in the frame that gets mistaken for a leak. While you are there, check your window’s manual: handles often have a seasonal setting and lubrication guidance, and the seals have care rules of their own.
Safety beats a spotless pane
Do not stand on the sill, do not lean out, and do not clean the outside above ground level without safe access. One pane is not worth the risk: where you cannot reach safely, clean the inside and leave the rest to people with the right equipment.
Knowing when to stop
The glass is clean when viewed at an angle, not just against the light; frame, seals and channels are wiped; drainage slots are clear; the sill and outer ledge are washed; the screen is dry and back in place. Anything that needs a repair to the hardware is written down as its own task.
