Here is a nice followup to yesterday’s video: How to make your own ferrofluid.
This guide comes from Dr. Anne Marie Helmenstine at About.com The fine folks at Sci-spot seem to have the original with pictures. The composition of ferrofluid by volume is about 5% magnetic solids, 10% surfactant, and 85% carrier. The surfactant is what keeps the particles from sticking together permanently. Ferrofluids are often used for damping speakers and in disk drives. This procedure doesn’t seem to complex and one of the main components is ferric chloride, a.k.a. PCB etchant. Thanks go to [Jason Uher] who sent in this tip and says that it has worked out quite well for him in the past.