Technique · Fields
Ferrofluid
Black magnetic liquid pulled into a hexagonal lattice of glossy spikes that rise and fall with the field.
Ferrofluid is a field drawn for every pixel by the graphics chip. Every piece on Synapse Drip is made from a recipe that layers techniques like this one, and you can change any of it in the Studio.
Good to know
- Above a critical field strength a flat ferrofluid surface breaks into a lattice of spikes; the effect is named the Rosensweig instability after the engineer who studied it in the 1960s.
- The artist Sachiko Kodama made ferrofluid sculptures that rise and flow with music, including the work Protrude, Flow in 2001.
- Each spike is held up by the magnetic field and pulled down by gravity and surface tension, and the balance between them fixes the distance between spikes, which is typically a few millimetres to a centimetre.
- Ferrofluid was developed at NASA in 1963 by Steve Papell, as a fuel that could be pulled toward a pump by a magnet in weightlessness.
- It is a black liquid carrying magnetic particles only about ten nanometres across, each coated so that they never clump; it is used in loudspeakers and in the seals of hard disk drives.
The mathematics
- The spikes sit on a hexagonal lattice, the densest way to pack equal discs; here the spacing is 0.130 of the picture's height, about 8 to a row, and each spike is a concave cone of height proportional to the field.
- The reflections are worked out by mirroring the view direction in the surface normal and looking up the light that way, so a steep spike reflects the sides of the room and a flat valley reflects the ceiling.
- Each spike has its own small phase in the pulse of the field, so the lattice breathes unevenly, with some spikes rising while their neighbours sink, instead of all moving together.
In art
- Black, glossy and slowly moving, ferrofluid has become a favourite of designers and photographers, who light it with a few strips of white so that only the edges shine.
- Kinetic artists have long used magnetic and fluid forces, because the form is made by physics in front of the audience.
More ways to use it
Related techniques
Nebula and stars · Liquid · Droplets · Network · Terrain and maps · Neuron · Order to chaos · Fractal tree