Magnet Pole Sensor Foil / Flux Detector card neodymium alnico ferrite smco

Do you remember those experiments in school with iron filings and magnets? This is an easier way to see a static magnetic field and a lot less messy!

This is a micro-encapsulated foil of set within a cardboard holder to protect the rear of the film from damage. Each card has a viewing window of 35 x 35mm. When it's held directly onto the surface of a magnetic material it will instantly reveal the magnetic field of any shape or pattern. A handy cross on the reverse indicates where to hold the magnet so that it's central to the viewing window.

It's used in quality control (weak spots or cracks in magnets show up as spots or lines), product demonstration, education, reverse engineering and product authentication but it's also a lot of fun. In three of the pictures above we've placed it over a magnet - flexible strip, a neodymium disk and a neodymium block magnet. Flexible strip is 'multi-polar' which means they have stripes of alternating north and south polarisation. The film clearly shows this. Each dark stripe represents a stripe of the flexible strip polarised in a single direction. The bright stripes in between the dark ones show where the poles meet and the magnetism from each stripe is cancelled out. When it's used on a stack of magnets it shows the interplay between the poles of each magnet in the stack which can be very beautiful.

Once the foil is removed from the magnet the image remains for some time before it disipates. However, if you want to use the foil again instantly, you can but it will erase the previous image at the same time.