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Sky Stack semi-invisible chimney


December 6, 2012

A disused smoke stack in the town of Kassel, more or less at the very heart of Germany, has undergone a peculiar transformation (Photo: asdfg)

A disused smoke stack in the town of Kassel, more or less at the very heart of Germany, has undergone a peculiar transformation (Photo: asdfg)

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A disused smoke stack in the town of Kassel, more or less at the very heart of Germany, has undergone a peculiar transformation. Glance up at the tower and the you will be met by the disarming sight of alternating floating and missing sections of chimney stack, courtesy of a bold intervention, named Sky Stack, by asdfg Architekten.

Apparently fixated by the existential worth of obsolete industrial architecture and infrastructure, asdfg (try typing that on a qwerty keyboard) has, through this modification, attempted to prompt the same wondering in others.

Close up, it's clear that this is a simple trick. There are no cameras, no screens; instead, they do it with mirrors. More accurately, five flexible reflective strips have been wrapped around the chimney, creating the impression, especially at a distance, that the stack is broken by the sky.

Judging by the photography, from the right vantage point with the right conditions, the effect is really rather striking.

Sources: asdfg, Architizer

About the Author
James Holloway James lives in East London where he punctuates endless tea drinking with freelance writing and meteorological angst. Unlocking Every Extend Extra Extreme’s “Master of Extreme” achievement was the fourth proudest moment of his life. All articles by James Holloway

Didn't go far enough. Wrap the whole tower in reflective sheets. Then you got something...


As if enough birds aren't killed by flying into windows. Very stupid idea and apparently given absolutely no thought to the negatives of such a strategy.


or a trompe l'oeil sky painting might work as well, and not reflect buildings, etc. I kind of like the floating blocks of chimney, though.


@Buellrider - you've clearly never seen a bird hit a window. They drop to the ground, shake their head, and fly away.


christopher, I've disposed of enough that didn't get back up again to know that it's not a rare occurrence that they kill themselves in the process. That being said, if the reflective bands have any sort of pattern that you can only see once you get close, like 3M's reflective tapes, I think the birds would pick up on it in time to avoid collision.

Siegfried Gust

@christopher - birds do not always recover so easily. We just had an incident in our city where nearly a whole flock of Bohemian Waxwings were killed when they flew into a glass art structure in front of the Scouts building.

Kim Bilida

Not so Christopher. Very many die.


Convex mirror? The birds will see their stretched reflection with plenty of time to avoid the stack.

Charles Bosse

Think people this is not transparent it is reflective. As the birds get close they will see their reflection think it is an oncoming bird and turn away.

Robin McCabe

?"...the existential worth of obsolete industrial architecture and infrastructure..."

I guess a solar steam power plant hadn't crossed the 'artists' mind in the first place. It could stand to be taller- then it would need a light at the top...


Actually, the angle reflects the horizon for any observer on the ground, hence the illusion of sky. From head on (bird's eye) however, the mirrors might partially reflect the ground making the tower look distinctly different and easily avoidable. Maybe a bit confusing for a helicopter at night though :b

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