Direct sun
On a sunny day, glass heats up. Cleaning solution on a warm pane dries in seconds, before the squeegee gets to it, and whatever was dissolved in the water stays behind as a haze. Window cleaning suppliers describe it as ghosting: a cloudy film left by dried minerals and detergent.
Heat causes a second problem. It softens the squeegee rubber, so the blade loses its sharp edge and leaves more water behind.
The fix is timing. Work the shaded side of a building first and follow the shade round, or clean sunny elevations early and late in the day.
Too much detergent
A little detergent helps the solution glide and lift dirt. Too much leaves a film that no squeegee can fully remove, and it shows as a greasy smear when the light hits it.
Use a product made for glass at its stated dose. Impact Glass, Mirror and VDU Cleaner is a concentrate that goes a long way in a trigger bottle or bucket, and Brite Glass Cleaner comes ready to use in a 750ml trigger for mirrors, glass doors and stainless steel.
A worn rubber
A single thin line of water in the same place on every pane means a nicked rubber. A wide damp band means the edge has rounded off. Turn the rubber over to use its second edge, or fit a new channel and rubber. Our article on squeegee rubbers goes into more detail.
A clogged cloth or dirty water
The finishing cloth picks up whatever is on it. A microfibre washed with fabric softener smears instead of absorbing, and a cloth used on the frames transfers grime back onto the glass. Keep separate cloths for frames and glass, wash microfibre without softener, and use a chamois for edges and sills.
Change the water in the bucket as soon as it looks grey. Dirty water carries dirt straight back onto the pane.
Why streaks show up from October
From October the sun sits low and shines straight through the glass at eye level. In Liverpool the midday sun is about 60 degrees above the horizon in June and below 30 degrees by mid October. Every streak and smear that went unnoticed in summer suddenly shows, which is why offices and shops in Liverpool notice their windows most from October to February.
The kit that stops most streaks
- A sharp rubber in the right width of squeegee channel
- A clean wash sleeve on the T bar
- A glass cleaner at its correct dose
- A bucket of fresh water, changed often
- A clean microfibre or chamois for the edges And for buildings where the windows are simply too many or too high, our window cleaning teams cover every window, inside and out, in one visit.