The current issue of The New Yorker has a fascinating (and, sadly, subscription-only) article about how the windows of NYC’s skyscrapers get washed. It turns out newfangled skyscraper architecture can make it difficult to use conventional window-washing methods—and that’s just one of many fun facts we learned from the story. Here are five more:

1) The Empire State Building is particularly tough to clean because tenants on higher floors often throw things out of the windows. “One time,” says one building window cleaner, “they threw, like, twenty gallons of strawberry preserves—and it went through ten floors, all over the windows. And it was the winter, so it froze on there and we couldn’t get it off.”

2) Designing a cleaning rig that could that clean the Hearst Tower took the engineers at Tractel-Swingstage three years (and around $3 million); the company’s vice-president of engineering had never seen anything like what Foster and Partners’ called the building’s “bird’s mouths.”

3) A building’s size is measured, for cleaning, in “drops”—”a single vertical section of the facade running from the roof to the lowest point the basket can descend.” That lowest point might be a setback or other architectural feature, or it might be the ground.

4) The city’s first scaffolding for window cleaning was built in 1952 and used to clean Park Avenue’s Lever House.

5) Because of the way they move, most window cleaners will end up leaving a “signature” on the window glass.

6) Cleaning the windows of Manhattan skyscrapers takes a long time: “One days’ work on an average drop takes around four hours; given good wather it, it takes a month to clean the whole [Hearst] tower from top to bottom. Work on larger skyscrapers in the city takes much longer: a single cleaning cycle on the eighty-story black glass curtain walls of the Time Warner Center, where the central ‘canyon drop’ alone descends seven hundred feet, from the roof to the fourth-floor setback, can take six men four months.”

Monday, January 28, 2013, by Sara Polsky