I am always at a loss for words whenever it's a roasting hot sunny day and I'm washing windows and a passer by comments: "Great day to wash windows!".
Now, my normal reply to that is something along the lines of: " Its actually a great day for lots of things, like golfing, fishing, swimming.. etc" The truth that most people don't realize is that it's actually the worst time to wash windows. Not because I'd rather be working on my slice at the driving range, the fact is that hot glass is a pain in the..uh, lower back.
When the sun gets hot surface temperatures on windows can reach levels above 100 degrees fahrenheit. This results in very fast evaporation which is detrimental to the squeegee cleaning method which relies on wet lubricated glass in order to achieve a streak free finish. We as window cleaners have to deal with this in several ways because the last thing we want is to have to come back again and rub off some foggy streaks or rubber lines.
First one is obvious, we start early as possible in the day. Its cool then and the glass is too. If the sun is already high in the sky and the heat is on, then we start on the shady side of the building, and most likely when we finish that side, the earth has rotated and the angle of sunlight has shifted away from the hot side. Besides that, keeping the water in my bucket ice cold and lots of it helps to cool hot glass down before my squeegee touches it, you can't put too much water on that window on a hot day. Then there is the actual rubber that is in the squeegee. Surprisingly there are lot's of different companies making various rubber compounds for window cleaners. Some are cheap, some are not, but you get what you pay for. In my research I have found that Ettore Soren rubber is probably the most durable and reliable rubber on the market. I've used it on extremely hot windows with practically no water at all and there have been little to no streaking left behind!
The Window Viper