Why has the window cleaner left my windows wet?

It looks like the job was left half done. It is actually the part that makes it work.

· Liam, Aqua Glaze

You come home, the windows are dripping, and there is no sign of a cloth anywhere. It is the single most common thing people ask us, and it is a completely fair question, because it is the opposite of how windows were cleaned for the last hundred years.

Here is the short version: the water dries by itself and leaves nothing behind. Wiping it off would make it worse.

Tap water carries chalk and salts Pure water carries nothing at all wet drying a spot wet drying nothing Dry it off and you smear those minerals across the glass. Leave it and it vanishes, taking the dirt with it.
The whole thing in one picture. Ordinary water leaves its minerals on the glass when it dries. Pure water has had them taken out, so there is nothing left to dry on.

What is different about the water

Turn on a tap and the water looks clear, but it is carrying dissolved chalk, salts and minerals. You cannot see them until the water dries, and then you can: that is what limescale on a shower screen is, and it is what those little white rings on a car are after rain.

The water on your windows has had all of that stripped out of it. It goes through a filter fine enough that only water molecules get through, so what lands on your glass is as close to pure H2O as it gets. When it evaporates there is genuinely nothing to leave behind.

Traditional cleaning has to be dried off, because the soapy water WOULD leave marks.

Pure water has to be left alone, for exactly the same reason in reverse.

So why not just dry it anyway?

Because a cloth is never clean for long. Wipe one window and the cloth picks up whatever came off it, then you carry that to the next one. You also press the last of the dirt into the corners rather than letting it run out.

The rinse is the finish. The water sheets down the glass, carries the loosened dirt off the bottom edge, and what stays behind is a thin film of pure water that disappears.

A water fed pole rinsing an upstairs window with pure water, the glass left wet and running clear
The rinse is not the mess at the end of the job. It is the job.

How long until they are dry?

  • 0 minWe finish and leaveGlass, frames and sills have all been scrubbed and rinsed with pure water. It looks wet, because it is.
  • 20 to 40 minIt dries on its ownLonger on a cold damp day, minutes on a breezy one. Nothing needs wiping and nothing needs doing at your end.
  • after thatClear glass, no marksThis is the point to judge it. If anything still looks wrong once it is properly dry, tell Liam and he will come back.

The bit that surprises people

Because there is no detergent left on the glass, there is nothing sticky for dust to cling to. Windows cleaned this way stay looking right noticeably longer, and when it rains you do not get that spotty, streaky look you used to get a few days after a clean.

That reaction with leftover detergent is why traditionally cleaned windows so often look worse after the first proper downpour. There is more on the two methods in water fed pole vs traditional cleaning, and on the water itself in what pure water actually is.

When it is worth saying something

Judge it once it is dry, not while it is wet. Wet glass tells you nothing, and a first clean on windows that have been left a long time can genuinely need a second go to shift everything out of the frames and seals.

If it is dry and something still is not right, say so. Liam would far rather come back than have you quietly decide it was not worth it. That is the whole point of a round you stay on rather than a one-off.

Prices and how it all works are on window cleaning, or get a figure for your own house on the instant quote page.

Questions people actually ask

Can I wipe them dry myself if I am in a hurry?

You can, but you will probably see the marks you were trying to avoid. Whatever is on the cloth goes onto the glass. Leaving it is genuinely the better result.

What about the frames and sills, they are wet too?

They get washed every visit, which is part of why it looks so wet when we leave. They dry the same way and it is worth having done: most of the grime on a window lives in the frame, not the glass.

It is raining. Are you really cleaning my windows in the rain?

Yes, and it does not affect the result. Rain is naturally soft water and the glass is already clean underneath. What would spoil a clean is high wind, and Liam does not put a pole up in that.

Mine still look marked after they dried. What now?

Tell Liam. On a first clean after a long gap it is usually old grime working its way out of the seals and it settles after the next visit, but he would rather come and look than have you wondering.

How long do they stay clean for?

Longer than with the traditional method, because there is no detergent film attracting dust. Most people are on a 4 or 8 week round, and there is more on picking between them in how often windows need doing.