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Why is restaurant cutlery sometimes magnetic?

Filed in Gossip ,Ideas
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Two computational social science types I know were recently discussing why restaurant cutlery is sometimes magnetized. One recounted an incident in which he asked the waitstaff, and they said it was due to a cutlery catcher magnet in the dishwasher. Do a Web search and you will see that many people have the same suspicion. And while you’re on the Web, do a search on cutlery catcher magnets. They are usually mounted on commercial kitchen trash can lids.


We think this common explanation is wrong. The average piece of flatware just doesn’t come into contact with the catcher magnet with enough frequency or friction to magnetize it.

Here’s our theory.

Our first job was as a short-order cook at a country club. Our utensils were magnetized. We noticed we had a ball burnishing machine in the kitchen they would dump the cutlery in, like this:

Turns out ball burnishers can use magnets to move the balls around:

From http://www.steelmedia.com/burnishing-media-applications.htm:
“Techbuff steel burnishing media is used mainly in vibratory finishing machines, tumblers, rotary barrels, harperizers, centrifugal finishing equipment and magnetic polishers for mass finishing polishing processes.”

From http://riograndeblog.com/2013/10/magnetic-finishing-create-an-irresistibly-attractive-finish/:
“So how does a magnetic finisher work? In the base of the finisher, a motor spins a set of positive and negatively charged magnets. The magnetic field pulls the pins around the circumference of the bowl sitting on the base, causing the pins to collide with the objects inside, burnishing them to a shiny finish. ”

From https://www.google.com/patents/US1050534:
Magnetic force may be applied to the balls …”

And these machines can have magnetic lids to prevent ball loss:

From http://www.moreillon-gastro.ch/en/index.php?page=3&pageId=0&lang=en:
Ball Burnisher with Magnetic Lid which “reduces loss of balls by preventing stray balls from rolling off the machine”

And it seems to be known that ball burnishers magnetize things from this long link:
“A steel burnisher becomes slightly magnetic

Accordingly, we think the magnetic field in ball burnishers is the real cause of magnetized restaurant flatware.


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