Authentic Ferrofluid Sample in 10ml Vial - Comes With Neodymium Magnet!

Ferrofluid is a colloid of magnetite nanoparticles suspended in a carrier oil with a surfactant that keeps them from clumping. This sample comes as 10 ml in a sealed glass vial with a neodymium magnet disc included.

At rest it behaves as an ordinary black liquid. Bring the magnet close and it forms the familiar spiked pattern along the field lines, then relaxes when the magnet is withdrawn. That makes it a useful demonstration of magnetism, field geometry and surface tension for classrooms and science fairs, and a common subject for macro photography.