Window cleaners mostly use one of two methods: a mop and squeegee, or filtered water fed up a long pole to a brush. Both get glass clean. Each is better at different windows, so we use both. Here's how they work.
Squeegee
A little soap in the water lets it spread across the glass in a sheet. A wet mop scrubs the dirt loose into that sheet, and the squeegee blade pulls it all off in one pass before anything dries. The edges get a dry towel.
Its strength is control. Almost no water gets loose, which is what you want over a wood floor or a sill full of things.
Pure water
Tap water has minerals dissolved in it, and those minerals are what dry into spots. A deionizing filter takes them out. That filtered water goes up a pole to a soft brush, which scrubs the glass, and the window gets a final rinse with nothing but that water.
Nobody squeegees or towels it afterward. Whatever water is left dries without a trace, because there's nothing in it to leave behind. The pole also reaches second- and third-story glass from the ground, so there's no ladder against the house or in the flower beds.
What it won't do is remove spots that have already bonded to the glass. On a first visit to windows that have gone a few seasons, those come off by hand with hard-water stain removal before regular cleaning takes over.
Why it dries without spots
A water spot is what the water was carrying. When a drop dries, its minerals stay on the glass as a small white ring. Take the minerals out first and there's nothing left to make a spot.
There's no soap either. A squeegee job done carelessly can leave a thin soap film that holds onto dust and pollen. A pure-water rinse leaves bare glass.
Which one for which window
- Inside the house: squeegee, so nothing drips on floors or furniture.
- Upstairs glass outside: pure water, reached from the ground.
- Salty glass near the beach: pure water. The rinse flushes salt out of frame edges and weep holes that a blade skips over.
- Frames and sills outside: pure water. The brush cleans the whole window, not only the glass.
- Ground-floor glass outside: pure water, with a hand-squeegee finish.
Doing it yourself
Squeegeeing ground-floor windows is easy enough to learn: dish soap, a decent mop and blade, dry towels for the edges, and some patience while you get the stroke down.
Pure water at home is harder. You can buy deionizing cartridges, but our water is hard and uses them up fast. Once the rinse water gets above about 10 parts per million of dissolved solids, spots come back. If you try it, buy a TDS meter and go by the number, not how clear the water looks.
What we do
Exterior window cleaning is a pure-water wash and rinse from a water-fed pole, with a hand-squeegee finish on the ground floor. Interior window cleaning is squeegee work, because inside your house keeping the water under control comes first. Our process walks through a whole visit.
Either way, it only takes off what's on the glass today. Salt and sprinkler water start landing again tomorrow, which is why the outside is on a schedule every two months.
