demonstrations:making_ferrofluids

Making Ferrofluids

Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★★☆ Can be done by science teachers
Safety: ★☆☆ Minimal safety procedures required

Categories: Magnetism

Alternative titles: DIY Ferrofluid

Summary

Ferrofluids are liquids that behave like magnets when exposed to a magnetic field. By mixing iron filings with oil, you can create your own ferrofluid and watch it switch between liquid and solid-like states depending on whether a magnet is nearby.

Procedure

  1. Pour a thin layer of vegetable oil into a shallow dish.
  2. Add iron filings and mix until it becomes a thick sludge.
  3. Dab away excess oil with a napkin; placing a magnet against the dish can help solidify the ferrofluid so cleanup is easier.
  4. Hold a magnet near the dish: the ferrofluid will solidify into spiky patterns that trace the magnetic field.
  5. Remove the magnet: the ferrofluid relaxes and flows like a liquid again.


An alternative method using toner is given in the links below.

Making ferrofluid from scratch - NileRed:


How to make Magnetic Fluid (ferro fluid) - Household Hacker:


📄 Making Ferrofluids - National Maglab: https://nationalmaglab.org/magnet-academy/try-this-at-home/making-ferrofluids/

Variations

  • Try using different magnet strengths and shapes to see how the ferrofluid patterns change.
  • Use different container shapes (flat, convex, concave) and compare results.
  • Experiment with the ratio of filings to oil to make the fluid thinner or thicker.

Safety Precautions

  • Do not pour ferrofluid down the drain; dispose of it in the trash to avoid clogs.
  • Iron filings can be messy - work over newspaper or a tray.
  • Magnets can pinch fingers or damage electronics; handle with care.
  • Wash hands thoroughly after handling iron filings and oil.

Questions to Consider

  • What happens to each iron particle when exposed to a magnetic field?
  • Why do spiky cone-like patterns form in the ferrofluid?
  • How does the strength of the magnet affect the behavior of the ferrofluid?
  • Where are ferrofluids used in real-world applications (e.g., aerospace, electronics, art)?