Two possibilities, and by god I hope my first is right:
It's a super clever two-stage prank. At auction the picture is supposed to shred but it stops half way. Did it break? Was that the intention? Who knows! That's the mystery behind it. Now it's more than just a simple painting, it's a performance piece and worth significantly more! The half shredded portrait is hung up somewhere and weeks or months from now the shredder comes back to life for the finale of complete destruction. "Going... Going... Gone" became "Going up up and away!" Ha! Take that Banksy! Then full circle back to gone, Banksy has the last laugh. Bonus points if it does this in the middle of the night and the owner is greeted by a pile of shreds on the floor the following morning.
Second and more boring possibility: the shredder was supposed to fully destroy the picture at auction but unfortunately failed. I believe Banksy intended the piece to fully self destruct in full view of the auction house as a big "fuck you" to art hoarding and monetizing.
It's a super clever two-stage prank. At auction the picture is supposed to shred but it stops half way. Did it break? Was that the intention? Who knows! That's the mystery behind it. Now it's more than just a simple painting, it's a performance piece and worth significantly more! The half shredded portrait is hung up somewhere and weeks or months from now the shredder comes back to life for the finale of complete destruction. "Going... Going... Gone" became "Going up up and away!" Ha! Take that Banksy! Then full circle back to gone, Banksy has the last laugh. Bonus points if it does this in the middle of the night and the owner is greeted by a pile of shreds on the floor the following morning.
Second and more boring possibility: the shredder was supposed to fully destroy the picture at auction but unfortunately failed. I believe Banksy intended the piece to fully self destruct in full view of the auction house as a big "fuck you" to art hoarding and monetizing.