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DIY Ferrocell: How to make a magnetic field viewer

By squishing a mix of mineral oil and ferrofluid between two sheets of glass, diligently squeezing out the air bubbles, sealing the edges, and then lighting it with a LED strip, Magnetic Games has created a DIY magnetic field viewer. Watch as the fluid’s magnetic particles seem to bloom and move in reaction to the magnets on the glass.

This messy but mesmerizing DIY science experiment is based on a Ferrocell (or Ferrohydrodynamic Lens), a sealed piece of glass containing a 50 micron thick layer of ferrofluid. The black liquid appears transparent at this thickness, and according to ferrocell inventor Timm Vanderelli, it “behaves more like a gas than a liquid” in this state:

Apply light and magnetism to either surface. Polarization of the applied magnetic field will determine the “angle of incidence” light experiences as it exits the cell. Using a permanent magnet is the easiest way to apply a polar field and see how a Ferrocell will change the path of light and appear as a holographic image to the viewer.

See examples and products at, or you go the DIY route, see this precautionary note about handling ferrofluid via

Since the ferrofluid causes impossible to remove stains on clothing, it is recommended to use old clothing or an apron. It will also leave long lasting stains on the skin and on the cornea, therefore protective gloves and protective glasses are a good idea too.

Related videos: Ferrofluid + Glow Sticks, Dropping a neodymium magnet through a thick copper pipe, and how to make simple homopolar motor ‘race cars’.

Bonus: The Earth’s magnetic field helps foxes target mice in the snow.

h/t The Awesomer.

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