A question from the ancient days of open reel tape recording

[cvanc]

Hi all-

There used to be a small hand-held device that allowed you to see the magnetic modulation patterns recorded onto magnetic tape.  It looked a bit like a jewelers loupe - small, passive, handheld.  I would guess it consisted of something not too far removed from iron filings suspended in mineral oil.

Does anyone remember what this thing was called?  It was fairly common back in the days of razor blade editing... (did I just date myself?  LOL).

[StillTrying]

Magnetic Tape Viewer, I've never seen one in real life, but remember some open reel stuff.
http://www.tapeheads.net/showthread.php?t=39958

[tpowell1830]

There is a film nowadays that will reveal magnetic fields.

[Benta]

@StillTrying:
that link (the pictures) is incredibly cool. Thanks!

[Bryan]

Off topic but was watching a series called Mayday (plane crashes). One episode they had a black box that was so badly damaged the only way to analyze the data on the damaged tape was using a technology, I think called Granette ?? , where the 1' and 0's on the tape had to be viewed under a microscope with a special lens. They had to construct the bytes of data bit by bit through the microscope, would take days to recover 1 second of data. Couldn't imagine a more boring job.